TMP421

TMP421 BURR-BROWN | Alldatasheet

Document overview

• Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
• PDF pages: 26

Technical content

/C0066/C0117/C0114/C0114/C0262/C0066/C0114/C0111/C0119/C0110 /C0080/C0114/C0111/C0100/C0117/C0099/C0116/C0115 /C0102/C0114/C0111/C0109 /C0084/C0101/C0120/C0097/C0115 /C0073/C0110/C0115/C0116/C0114/C0117/C0109/C0101/C0110/C0116/C0115

FEATURES

DESCRIPTION

APPLICATIONS

ID□Register Manufacturer ID□Register Configuration RegisterStatus Register Conversion Rate Register N-Factor Correction DXP Resolution Register Pointer Register Configuration Register Remote T emperature Register Local T emperature Register GND DXN TMP421 Bus Interface SDASCL Device ID□Register Manufacturer ID□Register Configuration RegisterStatus Register Conversion Rate Register N-Factor Correction DX11 Resolution Register Pointer Register Configuration Register Remote T emperature Register Local T emperature Register DX2 TMP422 DX3 DX4 Bus Interface SDASCL

5 GND

C Remote and Local TEMPERATURE SENSOR in SOT23-8 SOT23-8 PACKAGE The TMP421 and TMP422 are remote temperature sensor monitors with a built-in local temperature C REMOTE DIODE SENSOR (MAX) sensor. The remote temperature sensor 1.5 C LOCAL TEMPERATURE SENSOR (MAX) diode-connected transistors are typically low-cost, SERIES RESISTANCE CANCELLATION NPN- or PNP-type transistors or diodes that are an n-FACTOR CORRECTION integral part of microcontrollers, microprocessors, or FPGAs. TWO-WIRE/ SMBus SERIAL INTERFACE Remote accuracy is C for multiple IC MULTIPLE INTERFACE ADDRESSES manufacturers, with no calibration needed. The DIODE FAULT DETECTION Two-Wire serial interface accepts SMBus write byte, RoHS COMPLIANT AND NO Sb/Br read byte, send byte, and receive byte commands to configure the device. the TMP421 and TMP422 include series resistance PROCESSOR/FPGA TEMPERATURE cancellation, programmable non-ideality factor, wide MONITORING remote temperature measurement range (up to LCD/ DLP /LCOS PROJECTORS +150 C), and diode fault detection. SERVERS The TMP421 and TMP422 are both available in an CENTRAL OFFICE TELECOM EQUIPMENT 8-lead, SOT23 package. STORAGE AREA NETWORKS (SAN) Please be aware that an important notice concerning availability, standard warranty, and use in critical sheet. DLP is a registered trademark of Texas Instruments. SMBus is a trademark of Intel Corporation. I2C is a trademark of NXP Semiconductors. All other trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Copyright 2007, Texas Instruments Incorporated Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters.

www.ti.com ABSOLUTE MAXIMUM RATINGS (1) TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. PACKAGE INFORMATION (1) I C PACKAGE PACKAGE PRODUCT (1) For the most current package and ordering information see the Package Option Addendum at the end of this document, or see the TI web site at www.ti.com Over operating free-air temperature range, unless otherwise noted. TMP420, TMP421 UNIT Power Supply, V S V Pins and only 0.5 to V S 0.5 V Input Voltage Pins and only 0.5 to V Input Current mA Operating Temperature Range to +127 C Storage Temperature Range to +130 C Junction Temperature J max) +150 C Human Body Model (HBM) 3000 V ESD Rating Charged Device Model (CDM) 1000 V Machine Model (MM) 200 V (1) Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those specified is not implied. Submit Documentation Feedback Copyright 2007, Texas Instruments Incorporated Product Folder Link(s): TMP421 TMP422

www.ti.com ELECTRICAL CHARACTERISTICS TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 At T A C to +125 C and V S 2.7V to 5.5V, unless otherwise noted. TMP421, TMP422 PARAMETER CONDITIONS MIN TYP MAX UNIT TEMPERATURE ERROR Local Temperature Sensor TE LOCAL T A C to +125 C 1.25 2.5 C T A +15 C to +85 V S 3.3V 0.25 1.5 C Remote Temperature Sensor (1) TE REMOTE T A +15 C to +85 T D C to +150 V S 3.3V 0.25 C T A C to +100 T D C to +150 V S 3.3V C T A C to +125 T D C to +150 C C vs Supply (Local/Remote) V S 2.7V to 5.5V 0.2 0.5 C/V TEMPERATURE MEASUREMENT Conversion Time (per channel) 100 115 130 ms Resolution Local Temperature Sensor (programmable) Bits Remote Temperature Sensor Bits Remote Sensor Source Currents High Series Resistance Ω Max 120 μ A Medium High μ A Medium Low μ A Low μ A Remote Transistor Ideality Factor η TMP421/TMP422 Optimized Ideality Factor 1.008 SMBus INTERFACE Logic Input High Voltage (SCL, SDA) V IH 2.1 V Logic Input Low Voltage (SCL, SDA) V IL 0.8 V Hysteresis 500 mV SMBus Output Low Sink Current mA SDA Output Low Voltage V OL I OUT 6mA 0.15 0.4 V Logic Input Current V IN μ A SMBus Input Capacitance (SCL, SDA) pF SMBus Clock Frequency 3.4 MHz SMBus Timeout ms SCL Falling Edge to SDA Valid Time μ s DIGITAL INPUTS Input Capacitance pF Input Logic Levels Input High Voltage V IH 0.7(V+) (V+)+0.5 V Input Low Voltage V IL 0.5 0.3(V+) V Leakage Input Current I IN V IN V S μ A POWER SUPPLY Specified Voltage Range V S 2.7 5.5 V Quiescent Current I Q 0.0625 Conversions per Second μ A Conversions per Second 400 525 μ A Serial Bus Inactive, Shutdown Mode μ A Serial Bus Active, f S 400kHz, Shutdown Mode μ A Serial Bus Active, f S 3.4MHz, Shutdown Mode 350 μ A Undervoltage Lockout UVLO 2.3 2.4 2.6 V Power-On Reset Threshold POR 1.6 2.3 V TEMPERATURE RANGE Specified Range +125 C Storage Range +130 C Thermal Resistance, SOT23 θ JA 100 C/W (1) Tested with less than Ω effective series resistance and 100pF differential input capacitance. Copyright 2007, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TMP421 TMP422

www.ti.com TMP421 PIN CONFIGURATION SCL GND DXP DXN SDA TMP421 TMP422 PIN CONFIGURATION SCL GND DX1 DX2 DX3 DX4 SDA TMP422 TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 DCN PACKAGE SOT23-8 (TOP VIEW) TMP421 PIN ASSIGNMENTS TMP421 NO. NAME sensor. DXN Negative connection to remote temperature sensor. Address pin Address pin GND Ground SDA Serial data line for SMBus, open-drain; requires pull-up resistor to V+. SCL Serial clock line for SMBus, open-drain; requires pull-up resistor to V+. Positive supply voltage (2.7V to 5.5V) DCN PACKAGE SOT23-8 (TOP VIEW) TMP422 PIN ASSIGNMENTS TMP422 NO. NAME pin. Also sets the TMP422 address; see Table DX2 Channel remote temperature sensor connection pin. Also sets the TMP422 address; see Table DX3 Channel remote temperature sensor connection pin. Also sets the TMP422 address; see Table DX4 Channel remote temperature sensor connection pin. Also sets the TMP422 address; see Table GND Ground SDA Serial data line for SMBus, open-drain; requires pull-up resistor to V+. SCL Serial clock line for SMBus, open-drain; requires pull-up resistor to V+. Positive supply voltage (2.7V to 5.5V) Submit Documentation Feedback Copyright 2007, Texas Instruments Incorporated Product Folder Link(s): TMP421 TMP422

www.ti.com TYPICAL CHARACTERISTICS /c45 1 /c45 2 /c45 3 Ambient□T emperature,□T ( C)/c176 A /c45 50 /c45 25 1251007550250 Remote□T emperature□Error□( C) /c176 V =□3.3VS T =□+25 CREMOTE /c176 30□T ypical□Units□Shown /c104 =□1.008 Local□T emperature□Error□( /c176C Ambient□T emperature,□T (A /c176 C) 3.0 2.0 1.0 /c45 1.0 /c45 2.0 /c45 3.0 /c45 50 125/c45 25 0 25 50 75 100 50□Units□ShownV =□3.3VS /c45 20 /c45 40 /c45 60 Leakage□Resistance□(M )/c87 0 5 10 15 20 25 30 Remote□T emperature□Error□( C) /c176 R GND/c45 R V S/c45 Remote□T emperature□Error□( /c176C R /c87( )S 2.0 1.5 1.0 0.5 /c45 0.5 /c45 1.0 /c45 1.5 /c45 2.0 0 3500500 1000 1500 2000 2500 3000 V =□2.7VS V =□5.5VS /c45 1 /c45 2 /c45 3 Capacitance□(nF) Remote□T emperature□Error□( C) /c176 Remote□T emperature□Error□( /c176C R ( /c87 )S 2.0 1.5 1.0 0.5 /c45 0.5 /c45 1.0 /c45 1.5 /c45 2.0 0 3500500 1000 1500 2000 2500 3000 V =□2.7VS V =□5.5VS TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 At T A +25 C and V S +5.0V, unless otherwise noted. REMOTE TEMPERATURE ERROR LOCAL TEMPERATURE ERROR vs TEMPERATURE vs TEMPERATURE Figure Figure REMOTE TEMPERATURE ERROR REMOTE TEMPERATURE ERROR vs SERIES RESISTANCE vs LEAKAGE RESISTANCE (Diode-Connected Transistor, 2N3906 PNP) Figure Figure REMOTE TEMPERATURE ERROR vs SERIES RESISTANCE REMOTE TEMPERATURE ERROR (GND Collector-Connected Transistor, 2N3906 PNP) vs DIFFERENTIAL CAPACITANCE Figure Figure Copyright 2007, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TMP421 TMP422

www.ti.com /c45 5 /c45 10 /c45 15 /c45 20 /c45 25 Frequency□(MHz) 0 5 10 15 T emperature□Error□( C) /c176 Local□100mV NoisePP Remote□100mV NoisePP Local□250mV NoisePP Remote□250mV NoisePP 500 450 400 350 300 250 200 150 100 Conversion□Rate□(conversions/sec) 0.0625 0.125 0.25 0.5 1 2 4 8 I ( /c109A) Q V =□2.7VS V =□5.5VS 500 450 400 350 300 250 200 150 100 SCL□CLock□Frequency□(Hz) 1k 10k 100k 1M 10M I ( A)/c109 Q V =□3.3VS V =□5.5VS I ( )Q /c109A V (S V) TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 TYPICAL CHARACTERISTICS (continued) At T A +25 C and V S +5.0V, unless otherwise noted. TEMPERATURE ERROR QUIESCENT CURRENT vs POWER-SUPPLY NOISE FREQUENCY vs CONVERSION RATE Figure Figure SHUTDOWN QUIESCENT CURRENT SHUTDOWN QUIESCENT CURRENT vs SCL CLOCK FREQUENCY vs SUPPLY VOLTAGE Figure Figure 10. Submit Documentation Feedback Copyright 2007, Texas Instruments Incorporated Product Folder Link(s): TMP421 TMP422

www.ti.com APPLICATION INFORMATION

0.1 F/c109 10k/c87

(typ) 10k/c87 (typ) TMP421 DXP DXN R S (2) RS (2) CDIFF (3) CDIFF (3) RS (2) RS (2) GND SCL SDA +5V SMBus Controller Diode-connected□configuration :(1) Series□Resistance Transistor-connected□configuration:(1) (1)□Diode-connected□configuration□provides□better□settling□time. Transistor-connected□configuration□provides□better□series□resistance□cancellation. (2)□R should□be□<□1.5k /c87 in□most□applications.S (3)□C should□be□<□1000pF□in□most□applications.DIFF NOTES: TMP422 DX1(4) DX2(4) RS (2) RS (2) CDIFF (3) CDIFF (3) RS (2) RS (2) GND Diode-connected□configuration :(1) Series□Resistance Transistor-connected□configuration:(1) (1)□Diode-connected□configuration□provides□better□settling□time. Transistor-connected□configuration□provides□better□series□resistance□cancellation. (2)□R should□be□<□1.5k /c87 in□most□applications. (3)□C should□be□<□1000pF□in□most□applications. (4)□TMP422□SMBus□slave□address□is when□connected□as□shown.1001□100 S DIFF NOTES: DX3(4) DX4(4)4 3RS (2) RS (2) CDIFF (3) (typ) 10k/c87 (typ) SCL SDA +5V SMBus Controller DXP1 DXN1 DXP2 DXN2 TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 For proper remote temperature sensing operation, the The TMP421 (two-channel) and TMP422 TMP421 requires only a transistor connected (three-channel) are digital temperature sensors that between DXP and DXN; the TMP422 requires combine a local die temperature measurement transistors connected between DX1 and DX2 and channel and one or two remote junction temperature between DX3 and DX4. The SCL and SDA interface measurement channels in a single SOT23-8 package. pins require pull-up resistors as part of the The TMP421/22 are Two-Wire- and SMBus communication bus. A 0.1 μ F power-supply bypass interface-compatible and are specified over a capacitor is recommended for good local bypassing. temperature range of C to +125 The Figure shows a typical configuration for the TMP421/22 contain multiple registers for holding TMP421, and Figure for the TMP422. configuration information and temperature measurement results. Figure 11. TMP421 Basic Connections Figure 12. TMP422 Basic Connections Copyright 2007, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TMP421 TMP422

www.ti.com SERIES RESISTANCE CANCELLATION DIFFERENTIAL INPUT CAPACITANCE TEMPERATURE MEASUREMENT DATA Standard Binary Temperature Data Calculation TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 Table Temperature Data Format (Local and Remote Temperature High Bytes) Series resistance in an application circuit that typically LOCAL/REMOTE TEMPERATURE REGISTER results from printed circuit board (PCB) trace HIGH BYTE VALUE C RESOLUTION) resistance and remote line length (see Figure is STANDARD BINARY EXTENDED BINARY TEMP automatically cancelled by the TMP421/22, BINARY HEX BINARY HEX preventing what would otherwise result in a 1100 0000 0000 0000 temperature offset. A total of up to Ω of series line 1100 1110 CE 0000 1110 resistance is cancelled by the TMP421/22, eliminating 1110 0111 0010 0111 the need for additional characterization and 0000 0000 0100 0000 temperature offset correction. See the two Remote Temperature Error vs Series Resistance typical 0000 0001 0100 0001 characteristic curves Figure and Figure for 0000 0101 0100 0101 details on the effect of series resistance and 0000 1010 0100 1010 power-supply voltage on sensed remote temperature 0001 1001 0101 1001 error. 0011 0010 0111 0010 0100 1011 1000 1011 100 0110 0100 1010 0100 The TMP421/22 tolerate differential input capacitance 125 0111 1101 1011 1101 BD of up to 1000pF with minimal change in temperature 127 0111 1111 1011 1111 BF error. The effect of capacitance on sensed remote 150 0111 1111 1101 0110 temperature error is illustrated in Figure Remote 175 0111 1111 1110 1111 EF Temperature Error vs Differential Capacitance 191 0111 1111 1111 1111 FF (1) Resolution is C/count. Negative numbers are represented in Two's Complement format. Temperature measurement data are taken over a (2) Resolution is C/count. All values are unsigned with a C default range of C to +127 C for both local and offset. remote locations. Measurements from C to Both local and remote temperature data use two +150 C can be made both locally and remotely by bytes for data storage. The high byte stores the reconfiguring the TMP421/22 for the extended temperature with C resolution. The second or low temperature range. To change the TMP421 and byte stores the decimal fraction value of the TMP422 configuration from the standard to the temperature and allows a higher measurement extended temperature range, switch bit (RANGE) of resolution; see Table The measurement resolution the Configuration Register from low to high. for the both the local and remote channels is Temperature data resulting from conversions within 0.0625 and is not adjustable. the default measurement range are represented in binary form, as shown in Table Standard Binary column. Note that any temperature below C Example results in a data value of (C0h). Likewise, For positive temperatures (for example, C): temperatures above +127 C result in a value of 127 (20 C)/(1 C/count) 14h 0001 0100 (7Fh). The device can be set to measure over an extended temperature range by changing bit of Two's Complement is not performed on positive Configuration Register from low to high. The numbers. Simply convert the number to binary change in measurement range and data format from code with 8-bit, right-justified format, and standard binary to extended binary occurs at the next MSB '0' to denote a positive sign. temperature conversion. For data captured in the C is stored as 0001 0100 14h. extended temperature range configuration, an offset For negative temperatures (for example, 20C): of (40h) is added to the standard binary value, as shown in the Extended Binary column of Table 20|)/(1 C/count) 14h 0001 0100 This configuration allows measurement of Generate the Two's Complement of a negative temperatures as low as and as high as number by complementing the absolute value +191 however, most temperature-sensing diodes binary number and adding only measure with the range of C to +150 C is stored as 1110 1100 ECh. Additionally, the TMP421/22 are rated only for ambient temperatures ranging from C to +125 Parameters in the Absolute Maximum Ratings table must be observed. Submit Documentation Feedback Copyright 2007, Texas Instruments Incorporated Product Folder Link(s): TMP421 TMP422

www.ti.com POINTER REGISTER One-Shot□Start□Register Configuration□Registers Status□Register Identification□Registers N-Factor□Correction□Registers Conversion□Rate□Register Local□and□Remote□T emperature□Registers SDA SCL Pointer□Register I/O Control Interface Software□Reset REGISTER INFORMATION TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 Table Decimal Fraction Temperature Data Format (Local and Remote Temperature Low Figure shows the internal register structure of the Bytes) TMP421/22. The 8-bit Pointer Register is used to TEMPERATURE REGISTER LOW BYTE VALUE address a given data register. The Pointer Register (0.0625 C RESOLUTION) (1) TEMP identifies which of the data registers should respond STANDARD AND EXTENDED BINARY HEX to a read or write command on the Two-Wire bus. 0000 0000 This register is set with every write command. A write 0.0625 0001 0000 command must be issued to set the proper value in 0.1250 0010 0000 the Pointer Register before executing a read 0.1875 0011 0000 command. Table describes the pointer address of 0.2500 0100 0000 the TMP421/22 registers. The power-on reset (POR) 0.3125 0101 0000 value of the Pointer Register is 00h (0000 0000b). 0.3750 0110 0000 0.4375 0111 0000 0.5000 1000 0000 0.5625 1001 0000 0.6250 1010 0000 0.6875 1011 0000 0.7500 1100 0000 0.8125 1101 0000 0.8750 1110 0000 0.9385 1111 0000 (1) Resolution is 0.0625 C/count. All possible values are shown. The TMP421/22 contain multiple registers for holding Figure 13. Internal Register Structure configuration information, temperature measurement results, and status information. These registers are described in Figure and Table Table Register Map BIT (HEX) (HEX) REGISTER (High Byte) (1) RT11 RT10 RT9 RT8 RT7 RT6 RT5 RT4 Remote Temperature (High Byte) (1) RT11 RT10 RT9 RT8 RT7 RT6 RT5 RT4 Remote Temperature (High Byte) (1) (2) BUSY Status Register SD RANGE Configuration Register 1C/3C (2) REN2 (2) REN LEN RC Configuration Register Conversion Rate Register X X X X X X X X One-Shot Start (3) LT3 LT2 LT1 LT0 nPVLD Local Temperature (Low Byte) RT3 RT2 RT1 RT0 nPVLD OPEN Remote Temperature (Low Byte) RT3 RT2 RT1 RT0 nPVLD OPEN Remote Temperature (Low Byte) (2) NC7 NC6 NC5 NC4 NC3 NC2 NC1 NC0 N Correction NC7 NC6 NC5 NC4 NC3 NC2 NC1 NC0 N Correction (2) FC X X X X X X X X Software Reset (4) FE Manufacturer ID TMP421 Device ID FF TMP422 Device ID (1) Compatible with Two-Byte Read; see Figure (2) TMP422 only. (3) X undefined. Writing any value to this register initiates a one-shot start; see the One-Shot Conversion section. (4) X undefined. Writing any value to this register initiates a software reset; see the Software Reset section. Copyright 2007, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TMP421 TMP422

www.ti.com TEMPERATURE REGISTERS STATUS REGISTER CONFIGURATION REGISTER TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 The TMP421/22 have four 8-bit registers that hold The Status Register reports the state of the temperature measurement results. Both the local temperature ADCs. Table shows the Status channel and the remote channel have a high byte Register bits. The Status Register is read-only, and is register that contains the most significant bits (MSBs) read accessing pointer address 08h. of the temperature analog-to-digital converter (ADC) The BUSY bit '1' if the ADC is making a conversion; result and a low byte register that contains the least it is set to '0' if the ADC is not converting. significant bits (LSBs) of the temperature ADC result. The local channel high byte address is 00h; the local channel low byte address is 10h. The remote channel high byte is at address 01h; the remote channel low Configuration Register (pointer address 09h) sets byte address is 11h. For the TMP422, the second the temperature range and controls shutdown mode. remote channel high byte address is 02h; the second The Configuration Register is set by writing to pointer remote channel low byte is 12h. These registers are address 09h and read by reading from pointer read-only and are updated by the ADC each time a address 09h. temperature measurement is completed. The shutdown (SD) bit (bit enables or disables the The TMP421/22 contain circuitry to assure that a low temperature measurement circuitry. If SD '0', the byte register read command returns data from the TMP421/22 converts continuously at the rate set in same ADC conversion as the immediately preceding the conversion rate register. When SD is set to '1', high byte read command. This assurance remains the TMP421/22 stops converting when the current valid only until another register is read. For proper conversion sequence is complete and enters a operation, the high byte of a temperature register shutdown mode. When SD is set to '0' again, the should be read first. The low byte register should be TMP421/22 resumes continuous conversions. When read in the next read command. The low byte register SD '1', a single conversion can be started by writing may be left unread if the LSBs are not needed. to the One-Shot Register. Alternatively, the temperature registers may be read The temperature range is set by configuring bit of as a 16-bit register by using a single two-byte read the Configuration Register. Setting this bit low command from address 00h for the local channel configures the TMP421/22 for the standard result, or from address 01h for the remote channel measurement range C to +127 C); temperature result (02h for the second remote channel result). conversions will be stored in the standard binary The high byte is output first, followed by the low byte. format. Setting bit high configures the TMP421/22 Both bytes of this read operation are from the same for the extended measurement range C to ADC conversion. The power-on reset value of all +150 C); temperature conversions will be stored in temperature registers is 00h. the extended binary format (see Table Table Status Register Format STATUS REGISTER (Read 08h, Write NA) BIT BIT NAME BUSY POR VALUE (1) (1) FOR TMP421: The BUSY changes to '1' almost immediately 100 μ following power-up, as the TMP421 begins the first temperature conversion. It is high whenever the TMP421 converts a temperature reading. FOR TMP422: The BUSY bit changes to '1' approximately 1ms following power-up. It is high whenever the TMP422 converts a temperature reading. Submit Documentation Feedback Copyright 2007, Texas Instruments Incorporated Product Folder Link(s): TMP421 TMP422

www.ti.com CONFIGURATION REGISTER TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 The remaining bits of the Configuration Register are The LEN bit enables the local temperature reserved and must always be set to '0'. The power-on measurement channel. If LEN '1', the local channel reset value for this register is 00h. Table is enabled; if LEN '0', the local channel is disabled. summarizes the bits of the Configuration Register. The REN bit enables external temperature measurement channel (connected to pins and 2.) If REN '1', the external channel is enabled; if REN '0', the external channel is disabled. Configuration Register (pointer address 0Ah) controls which temperature measurement channels For the TMP422 only, the REN2 bit enables the are enabled and whether the external channels have second external measurement channel (connected to the resistance correction feature enabled or not. pins and 4.) If REN2 '1', the second external channel is enabled; if REN '0', the second external The RC bit enables the resistance correction feature channel is disabled. for the external temperature channels. If RC '1', series resistance correction is enabled; if RC '0', The temperature measurement sequence is local resistance correction is disabled. Resistance channel, external channel external channel correction should be enabled for most applications. shutdown, and delay (to set conversion rate, if However, disabling the resistance correction may necessary). The sequence starts over with local yield slightly improved temperature measurement channel. If any of the channels are disabled, they are noise performance, and reduce conversion time by skipped in the sequence. about 50%, which could lower power consumption when conversion rates of two per second or less are selected. Table Configuration Register Bit Descriptions CONFIGURATION REGISTER (Read/Write 09h, POR 00h) BIT NAME FUNCTION POWER-ON RESET VALUE Reserved Run SD Shut Down Reserved C to +127 C Temperature Range C to +150 C Reserved Table Configuration Register Bit Descriptions CONFIGURATION REGISTER (Read/Write 0Ah, POR 1Ch for TMP421; 3Ch for TMP422) BIT NAME FUNCTION POWER-ON RESET VALUE Reserved External Channel Disabled (TMP422) REN2 External Channel Enabled (TMP421) External Channel Disabled REN External Channel Enabled Local Channel Disabled LEN Local Channel Enabled Resistance Correction Disabled RC Resistance Correction Enabled Reserved Copyright 2007, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TMP421 TMP422

www.ti.com CONVERSION RATE REGISTER ONE-SHOT CONVERSION TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 The Conversion Rate Register (pointer address 0Bh) When the TMP421/22 are in shutdown mode (SD controls the rate at which temperature conversions in the Configuration Register 1), a single conversion are performed. This register adjusts the idle time is started on all enabled channels by writing any between conversions but not the conversion timing value to the One-Shot Start Register, pointer address itself, thereby allowing the TMP421/22 power 0Fh. This write operation starts one conversion; the dissipation to be balanced with the temperature TMP421/22 return to shutdown mode when that register update rate. Table shows the conversion conversion completes. The value of the data sent in rate options and corresponding current consumption. the write command is irrelevant and is not stored by A one-shot command can be used during the idle the TMP421/22. When the TMP421/22 are in time between conversions to immediately start shutdown mode, the conversion sequence currently temperature conversions on all enabled channels. in process must be completed before a one-shot command can be issued. One-shot commands issued during a conversion are ignored. Table Conversion Rate Register CONVERSION RATE REGISTER (Read/Write 0Bh, POR 07h) AVERAGE I Q (TYP) μ CONVERSIONS/SEC V S 2.7V V S 5.5V 0.0625 0.125 0.25 0.5 103 128 155 (1) 190 220 (2) 373 413 (1) Conversion rate shown is for only one or two enabled measurement channels. When three channels are enabled, the conversion rate is and conversions-per-second. (2) Conversion rate shown is for only one enabled measurement channel. When two channels are enabled, the conversion rate is conversions-per-second. When three channels are enabled, the conversion rate is and conversions-per-second. Submit Documentation Feedback Copyright 2007, Texas Instruments Incorporated Product Folder Link(s): TMP421 TMP422

www.ti.com n-FACTOR CORRECTION REGISTER SOFTWARE RESET V BE2 /C0042V BE1 /C0043nkT q ln/C0466I2 /C0467 (1) IDENTIFICATION REGISTERS neff/C00431.008/C0032300 /C0466300 /C0042N ADJUST /C0467 (2) N ADJUST /C0043300 /C0042/C0466300 /C00321.008 neff /C0467 (3) BUS OVERVIEW TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 The TMP421/22 allow for a different n -factor value to The TMP421/22 may be reset by writing any value to be used for converting remote channel the Software Reset Register (pointer address FCh). measurements to temperature. The remote channel This action restores the power-on reset state to all of uses sequential current excitation to extract a the TMP421/22 registers as well as abort any differential V BE voltage measurement to determine conversion in process. The TMP421/22 also supports the temperature of the remote transistor. Equation reset via the two-wire general call address (0000 relates this voltage and temperature. 0000). The TMP421/22 acknowledges the general call address and responds to the second byte. If the second byte is 0000 0110, the TMP421/22 executes a software reset. The TMP421/22 takes no action in response to other values in the second byte. The value n in Equation is a characteristic of the particular transistor used for the remote channel. The default value for the TMP421/22 is n 1.008. The value in the n-Factor Correction Register may be The TMP421/22 allow for the Two-Wire bus controller used to adjust the effective n-factor according to to query the device for manufacturer and device IDs Equation and Equation to enable software identification of the device at the particular Two-Wire bus address. The manufacturer ID is obtained by reading from pointer address FEh. The device ID is obtained by reading from pointer address FFh. The TMP421/22 both return 55h for the manufacturer code. The TMP421 returns 21h for the device ID and the TMP422 returns 22h for the device The n -correction value must be stored in ID. These registers are read-only. two's-complement format, yielding an effective data range from 128 to +127. The n -correction value may be written to and read from pointer address 21h. (The The TMP421/22 is SMBus interface-compatible. In n-correction value for the second remote channel is SMBus protocol, the device that initiates the transfer read to/written from pointer address 22h.) The is called a master, and the devices controlled by the register power-on reset value is 00h, thus having no master are slaves. The bus must be controlled by a effect unless the register is written to. master device that generates the serial clock (SCL), controls the bus access, and generates the START Table n-Factor Range and STOP conditions. N ADJUST To address a specific device, a START condition is BINARY HEX DECIMAL n initiated. START is indicated by pulling the data line 0111 1111 127 1.747977 (SDA) from a high-to-low logic level while SCL is 0000 1010 1.042759 high. All slaves on the bus shift in the slave address 0000 1000 1.035616 byte, with the last bit indicating whether a read or 0000 0110 1.028571 write operation is intended. During the ninth clock 0000 0100 1.021622 pulse, the slave being addressed responds to the 0000 0010 1.014765 master by generating an Acknowledge and pulling 0000 0001 1.011371 SDA low. 0000 0000 1.008 Data transfer is then initiated and sent over eight 1111 1111 FF 1.004651 clock pulses followed by an Acknowledge bit. During 1111 1110 FE 1.001325 data transfer SDA must remain stable while SCL is 1111 1100 FC 0.994737 high, because any change in SDA while SCL is high 1111 1010 FA 0.988235 is interpreted as a control signal. 1111 1000 0.981818 Once all data have been transferred, the master 1111 0110 0.975484 generates a STOP condition. STOP is indicated by 1000 0000 128 0.706542 pulling SDA from low to high, while SCL is high. Copyright 2007, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TMP421 TMP422

www.ti.com SERIAL INTERFACE SERIAL BUS ADDRESS Two-Wire Interface Slave Device Addresses DX1 DX2 DX3 DX4 SCL SDA Address□=□1001100 Address□=□1001101 Address□=□1001110 Address□=□1001111 SCL SDA GND DX1 DX2 DX3 DX4 SCL SDA GND DX1 DX2 DX3 DX4 SCL SDA GND DX1 DX2 DX3 DX4 SCL SDA GND TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 Table TMP421 Slave Address Options TWO-WIRE SLAVE The TMP421/22 operate only as a slave device on ADDRESS either the Two-Wire bus or the SMBus. Connections 0011 100 Float to either bus are made via the open-drain I/O lines, SDA and SCL. The SDA and SCL pins feature 0011 101 Float integrated spike suppression filters and Schmitt 0011 110 Float triggers to minimize the effects of input spikes and 0011 111 Float bus noise. The TMP421/22 support the transmission 0101 010 Float Float protocol for fast (1kHz to 400kHz) and high-speed 1001 100 (1kHz to 3.4MHz) modes. All data bytes are transmitted MSB first. 1001 101 1001 110 1001 111 To communicate with the TMP421/22, the master The slave device address for the TMP422 is set by must first address slave devices via a slave address the connections between the external transistors and byte. The slave address byte consists of seven the TMP422 according to Figure and Table If address bits, and a direction bit indicating the intent one of the channels is unused, the respective DXP of executing a read or write operation. connection should be connected to GND, and the DXN connection should be left unconnected. The polarity of the transistor for external channel (pins The TMP421 supports nine slave device addresses and sets the least significant bit of the slave and the TMP422 supports four slave device address. The polarity of the transistor for external addresses. channel (pins and sets the next least significant bit of the slave address. The slave device address for the TMP421 is set by the and pins according to Table Table 10. TMP422 Slave Address Options TWO-WIRE SLAVE ADDRESS DX1 DX2 DX3 DX4 1001 100 DXP1 DXN1 DXP2 DXN2 1001 101 DXP1 DXN1 DXN2 DXP2 1001 110 DXN1 DXP1 DXP2 DXN2 1001 111 DXN1 DXP1 DXN2 DXP2 Figure 14. TMP422 Connections for Setup of Device Address Submit Documentation Feedback Copyright 2007, Texas Instruments Incorporated Product Folder Link(s): TMP421 TMP422

www.ti.com READ/WRITE OPERATIONS TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 The TMP422 checks the polarity of the external When reading from the TMP421/22, the last value transistor at power-on, or after software reset, by stored in the Pointer Register by a write operation is forcing current to pin while connecting pin to used to determine which register is read by a read approximately 0.6V. If the voltage on pin does not operation. To change the register pointer for a read pull up to near the VDD of the TMP422, pin operation, a new value must be written to the Pointer functions as DXP for this channel, and the second Register. This transaction is accomplished by issuing LSB of the slave address is '0'. If the voltage on pin a slave address byte with the W bit low, followed does pull up to near V+, the TMP422 forces current by the Pointer Register byte; no additional data are to pin while connecting pin to 0.6V. If the voltage required. The master can then generate a START on pin does not pull up to near V+, the TMP422 condition and send the slave address byte with the uses pin for DXP of channel and sets the second W bit high to initiate the read command. See LSB of the slave address to '1'. If both pins are Figure for details of this sequence. If repeated shorted to GND or if both pins are open, the TMP422 reads from the same register are desired, it is not uses pin as DXP and sets the address bit to '0'. necessary to continually send the Pointer Register This process is then repeated for channel (pins bytes, because the TMP421/22 retains the Pointer and 4). Register value until it is changed by the next write operation. Note that register bytes are sent MSB first, If the TMP422 is to be used with transistors that are followed by the LSB. located on another IC (such as a CPU, DSP, or graphics processor), it is recommended to use pin Read operations should be terminated by issuing a or pin as DXP to assure correct address detection. Not-Acknowledge command at the end of the last If the other IC has a lower supply voltage or is not byte to be read. For a single-byte operation, the powered when the TMP422 tries to detect the slave master should leave the SDA line high during the address, a protection diode may turn on during the Acknowledge time of the first byte that is read from detection process and the TMP422 may incorrectly the slave. For a two-byte read operation, the master choose the DXP pin and slave address. Using pin must pull SDA low during the Acknowledge time of and/or pin for transistors that are on other ICs will the first byte read, and should leave SDA high during ensure correction operation independent of supply the Acknowledge time of the second byte read from sequencing or levels. the slave. Accessing a particular register on the TMP421/22 is accomplished by writing the appropriate value to the Pointer Register. The value for the Pointer Register is the first byte transferred after the slave address byte with the W bit low. Every write operation to the TMP421/22 requires a value for the Pointer Register (see Figure Copyright 2007, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TMP421 TMP422

www.ti.com TIMING DIAGRAMS SCL SDA t(LOW) tR tF t(HDST A) t(HDST A) t(HDDA T) t(BUF) t(SUDA T) t(HIGH) t(SUST A) t(SUSTO) P S S P TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 Data Transfer: The number of data bytes transferred between a START and a STOP condition is not The TMP421/22 are Two-Wire and limited and is determined by the master device. The SMBus-compatible. Figure to Figure describe receiver acknowledges data transfer. the various operations on the TMP421/22. Parameters for Figure are defined in Table Acknowledge: Each receiving device, when Bus definitions are: addressed, is obliged to generate an Acknowledge bit. A device that acknowledges must pull down the Bus Idle: Both SDA and SCL lines remain high. SDA line during the Acknowledge clock pulse in such a way that the SDA line is stable low during the high Start Data Transfer: A change in the state of the period of the Acknowledge clock pulse. Setup and SDA line, from high to low, while the SCL line is high, hold times must be taken into account. On a master defines a START condition. Each data transfer is receive, data transfer termination can be signaled by initiated with a START condition. the master generating a Not-Acknowledge on the last Stop Data Transfer: A change in the state of the byte that has been transmitted by the slave. SDA line from low to high while the SCL line is high defines a STOP condition. Each data transfer terminates with a repeated START or STOP condition. Figure 15. Two-Wire Timing Diagram Table 11. Timing Characteristics for Figure FAST MODE HIGH-SPEED MODE PARAMETER MIN MAX MIN MAX UNIT SCL Operating Frequency f (SCL) 0.001 0.4 0.001 3.4 MHz Bus Free Time Between STOP and START Condition t (BUF) 600 160 ns Hold time after repeated START condition. After this period, the first clock t (HDSTA) 100 100 ns is generated. Repeated START Condition Setup Time t (SUSTA) 100 100 ns STOP Condition Setup Time t (SUSTO) 100 100 ns Data Hold Time t (HDDAT) (1) (2) ns Data Setup Time t (SUDAT) 100 ns SCL Clock LOW Period t (LOW) 1300 160 ns SCL Clock HIGH Period t (HIGH) 600 ns Clock/Data Fall Time t F 300 160 ns Clock/Data Rise Time t R 300 160 ns for SCL 100kHz t R 1000 (1) For cases with fall time of SCL less than 20ns and/or the rise or fall time of SDA less than 20ns, the hold time should be greater than 20ns. (2) For cases with a fall time of SCL less than 10ns and/or the rise or fall time of SDA less than 10ns, the hold time should be greater than 10ns. Submit Documentation Feedback Copyright 2007, Texas Instruments Incorporated Product Folder Link(s): TMP421 TMP422

www.ti.com Frame□1□T wo-□Wire□Slave□Address□Byte Frame□2□Pointer□Register□Byte Frame□4□Data□Byte□2 Start□By Master ACK□By TMP421/22 ACK□By TMP421/22 ACK□By TMP421/22 Stop□By Master 1 9 1 D7 D6 D5 D4 D3 D2 D1 D0 Frame□3□Data□Byte□1 ACK□By TMP421/22 D7SDA (Continued) SCL (Continued) D6 D5 D4 D3 D2 D1 D0 SDA SCL 0 0 1 1 0 0 (1) R/W P7 P6 P5 P4 P3 P2 P1 P0 /c188 /c188 NOTE:□(1)□Slave□address□1001100□shown. Frame□1□T wo-Wire□Slave□Address□Byte Frame□2□Pointer□Register□Byte Start□By Master ACK□By TMP421/22 ACK□By TMP421/22 Frame□3□T wo-Wire□Slave□Address□Byte Frame□4□Data□Byte□1□Read□Register Start□By Master ACK□By TMP421/22 NACK□By Master(2) From TMP421/22 1 9 1 9 1 9 1 9 SDA SCL 0 0 1 R/ W P7 P6 P5 P4 P3 P2 P1 P0 /c188 /c188 /c188 /c188 SDA (Continued) SCL (Continued) 1 0 0 1 1 0 0 (1) 1 0 0 (1) R/W D7 D6 D5 D4 D3 D2 D1 D0 (1)□Slave□address□1001100□shown. (2)□Master□should□leave□SDA□high□to□terminate□a□single-byte□read□operation. NOTES: TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 Figure 16. Two-Wire Timing Diagram for Write Word Format Figure 17. Two-Wire Timing Diagram for Single-Byte Read Format Copyright 2007, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TMP421 TMP422

www.ti.com Frame□1□T wo-Wire□Slave□Address□Byte Frame□2□Pointer□Register□Byte Start□By Master ACK□By TMP421/22 ACK□By TMP421/22 Frame□3□T wo-Wire□Slave□Address□Byte Frame□4□Data□Byte□1□Read□Register Start□By Master ACK□By TMP421/22 ACK□By Master From TMP421/22 1 9 1 9 1 9 1 9 SDA SCL 0 0 1 R/ W P7 P6 P5 P4 P3 P2 P1 P0 /c188 /c188 /c188 /c188 SDA (Continued) SCL (Continued) SDA (Continued) SCL (Continued) 1 0 0 1 1 0 0 (1) 1 0 0 (1) R/W D7 D6 D5 D4 D3 D2 D1 D0 Frame□5□Data□Byte□2□Read□Register Stop□By Master NACK□By Master(2) From TMP421/22 1 9 D7 D6 D5 D4 D3 D2 D1 D0 (1)□Slave□address□1001100□shown. (2)□Master□should□leave□SDA□high□to□terminate□a□two-byte□read□operation. NOTES: TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 Figure 18. Two-Wire Timing Diagram for Two-Byte Read Format Submit Documentation Feedback Copyright 2007, Texas Instruments Incorporated Product Folder Link(s): TMP421 TMP422

www.ti.com HIGH-SPEED MODE UNDERVOLTAGE LOCKOUT TIMEOUT FUNCTION GENERAL CALL RESET SHUTDOWN MODE (SD) FILTERING SENSOR FAULT TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 When not using the remote sensor with the TMP421, the DXP and DXN inputs must be connected together In order for the Two-Wire bus to operate at to prevent meaningless fault warnings. When not frequencies above 400kHz, the master device must using a remote sensor with the TMP422, the DX pins issue a High-Speed mode (Hs-mode) master code should be connected using Table such that DXP (0000 1xxx) as the first byte after a START condition connections are grounded and DXN connections are to switch the bus to high-speed operation. The left open (unconnected). TMP421/22 does acknowledge this byte, but switches the input filters on SDA and SCL and the output filter on SDA to operate in Hs-mode, allowing transfers at up to 3.4MHz. After the Hs-mode master code has The TMP421/22 sense when the power-supply been issued, the master transmits a Two-Wire slave voltage has reached a minimum voltage level for the address to initiate a data transfer operation. The bus ADC to function. The detection circuitry consists of a continues to operate in Hs-mode until a STOP voltage comparator that enables the ADC after the condition occurs on the bus. Upon receiving the power supply (V+) exceeds 2.45V (typical). The STOP condition, the TMP421/22 switches the input comparator output is continuously checked during a and output filters back to fast mode operation. conversion. The TMP421/22 does not perform a temperature conversion if the power supply is not valid. The PVLD bit (bit see Table of the Local/Remote Temperature Register is set to '1' and The TMP421/22 reset the serial interface if either the temperature result may be incorrect. SCL or SDA are held low for 30ms (typical) between a START and STOP condition. If the TMP421/22 are holding the bus low, it releases the bus and waits for a START condition. To avoid activating the timeout The TMP421/22 support reset via the Two-Wire function, it is necessary to maintain a communication General Call address 00h (0000 0000b). The speed of at least 1kHz for the SCL operating TMP421/22 acknowledge the General Call address frequency. and respond to the second byte. If the second byte is 06h (0000 0110b), the TMP421/22 execute a software reset. This software reset restores the power-on reset state to all TMP421/22 registers, and The TMP421/22 Shutdown Mode allows the user to aborts any conversion in progress. The TMP421/22 save maximum power by shutting down all device take no action in response to other values in the circuitry other than the serial interface, reducing second byte. current consumption to typically less than μ see Figure Shutdown Quiescent Current vs Supply Voltage Shutdown Mode is enabled when the SD bit of the Configuration Register is high; the device shuts Remote junction temperature sensors are usually down once the current conversion is completed. implemented in a noisy environment. Noise is most When SD is low, the device maintains a continuous often created by fast digital signals, and it can corrupt conversion state. measurements. The TMP421/22 have a built-in 65kHz filter on the inputs of DXP and DXN (TMP421), or on the inputs of DX1 through DX4 (TMP422), to minimize the effects of noise. However, a bypass The TMP421 can sense a fault at the DXP input capacitor placed differentially across the inputs of the resulting from incorrect diode connection. Both the remote temperature sensor is recommended to make TMP421 and the TMP422 can sense an open circuit. the application more robust against unwanted Short-circuit conditions return a value of 64h. The coupled signals. The value of this capacitor should be detection circuitry consists of a voltage comparator between 100pF and 1nF. Some (V+) 0.6V (typical). The comparator output is resistance; however, this increased accuracy is continuously checked during a conversion. If a fault is application-specific. When series resistance is added, detected, the OPEN bit (bit in the temperature the total value should not be greater than Ω If result register is set to '1' and the rest of the register filtering is needed, suggested component values are bits should be ignored. 100pF and Ω on each input; exact values are application-specific. Copyright 2007, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TMP421 TMP422

www.ti.com REMOTE SENSING MEASUREMENT ACCURACY AND THERMAL TERR /C0043/C0466n /C00421.008 1.008 /C0467/C0032/C0466273.15/C0041T/C0466/C0176C /C0467/C0467 (4) TERR /C0043/C04661.004/C00421.008 1.008 /C0467/C0032/C0466273.15/C0041100/C0176C /C0467 TERR /C00431.48/C0176C (5) TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 lowest sensed temperature. Base resistance 100 Ω The TMP421/22 are designed to be used with either discrete transistors or substrate transistors built into Tight control of V BE characteristics indicated by processor chips and ASICs. Either NPN or PNP small variations in h FE (that is, to 150). transistors can be used, as long as the base-emitter Based on these criteria, two recommended junction is used as the remote temperature sense. small-signal transistors are the 2N3904 (NPN) or NPN transistors must be diode-connected. PNP 2N3906 (PNP). transistors can either be transistor- or diode-connected (see Figure Errors in remote temperature sensor readings are CONSIDERATIONS typically the consequence of the ideality factor and The temperature measurement accuracy of the current excitation used by the TMP421/22 versus the TMP421/22 depends on the remote and/or local manufacturer-specified operating current for a given temperature sensor being at the same temperature transistor. Some manufacturers specify a high-level as the system point being monitored. Clearly, if the and low-level current for the temperature-sensing temperature sensor is not in good thermal contact substrate transistors. The TMP421/22 use μ A for with the part of the system being monitored, then I LOW and 120 μ A for I HIGH The TMP421/22 allow for there will be a delay in the response of the sensor to different n -factor values; see the N-Factor Correction a temperature change in the system. For remote Register section. The ideality factor n is a measured temperature-sensing a substrate characteristic of a remote temperature sensor diode transistor (or a small, SOT23 transistor) placed close as compared to an ideal diode. to the device being monitored, this delay is usually The ideality factor for the TMP421/22 is trimmed to not a concern. be 1.008. For transistors that have an ideality factor The local temperature sensor inside the TMP421/22 that does not match the TMP421/22, Equation can monitors the ambient air around the device. The be used to calculate the temperature error. Note that thermal time constant for the TMP421/22 is for the equation to be used correctly, actual approximately two seconds. This constant implies temperature must be converted to kelvins (K). that if the ambient air changes quickly by 100 it would take the TMP421/22 about seconds (that is, five thermal time constants) to settle to within C of the final value. In most applications, the TMP421/22 Where: package is in electrical, and therefore thermal, n ideality factor of remote temperature sensor contact with the printed circuit board (PCB), as well actual temperature as subjected to forced airflow. The accuracy of the measured temperature directly depends on how T ERR error in TMP421/22 due to n 1.008 accurately the PCB and forced airflow temperatures Degree delta is the same for C and K represent the temperature that the TMP421/22 is For n 1.004 and 100 measuring. Additionally, the internal power dissipation of the TMP421/22 can cause the temperature to rise above the ambient or PCB temperature. The internal power dissipated as a result of exciting the remote temperature sensor is negligible because of the small currents used. For a 5.5V supply and maximum conversion rate of eight conversions per second, the If a discrete transistor is used as the remote TMP421/22 dissipates 2.3mW (PD IQ 5.5V temperature sensor with the TMP421/22, the best 415 μ A). A θ JA of 100 C/W causes the junction accuracy can be achieved by selecting the transistor temperature to rise approximately +0.23 C above the according to the following criteria: ambient. Base-emitter voltage 0.25V at μ at the highest sensed temperature. Base-emitter voltage 0.95V at 120 μ at the Submit Documentation Feedback Copyright 2007, Texas Instruments Incorporated Product Folder Link(s): TMP421 TMP422

www.ti.com LAYOUT CONSIDERATIONS DXP DXN GND NOTE:□Use□minimum□5□mil□traces□with□5□mil□spacing. Ground□or□V+□layer on□bottom□and/or top,□if□□possible. TMP421 0.1/c109F□Capacitor GND PCB□Via DXP DXN TMP422 0.1/c109F□Capacitor GND PCB□Via DX1 DX2 DX3 DX4 TMP421 TMP422 SBOS398A JULY 2007 REVISED SEPTEMBER 2007 Remote temperature sensing on the TMP421/22 measures very small voltages using very low currents; therefore, noise at the IC inputs must be minimized. Most content, with several clocks and logic level transitions creating a noisy environment. Layout should adhere to the following guidelines: Place the TMP421/22 as close to the remote junction sensor as possible. Route the DXP and DXN traces next to each other and shield them from adjacent signals through the use of ground guard traces, as shown in Figure If a multilayer PCB is used, bury these traces between ground or V DD planes to shield them from extrinsic noise sources. mil PCB traces are recommended. Minimize additional thermocouple junctions caused by copper-to-solder connections. If these Figure 19. Suggested PCB Layer Cross-Section junctions are used, make the same number and approximate locations of copper-to-solder connections in both the DXP and DXN connections to cancel any thermocouple effects. Use a 0.1 μ F local bypass capacitor directly between the and GND of the TMP421/22, as shown in Figure Minimize filter capacitance between DXP and DXN to 1000pF or less for optimum measurement performance. This capacitance includes any cable capacitance between the remote temperature sensor and TMP421/22. If the connection between the remote temperature sensor and the TMP421/22 is less than in long, use a twisted-wire pair connection. Beyond in, use a twisted, shielded pair with the shield grounded as close to the TMP421/22 as possible. Leave the remote sensor connection end of the shield wire open to avoid ground loops and 60Hz pickup. Thoroughly clean and remove all flux residue in and around the pins of the TMP421/22 to avoid temperature offset readings due to leakage paths between DXP or DXN and GND, or between DXP or DXN and V+. Figure 20. Suggested Bypass Capacitor Placement and Trace Shielding Copyright 2007, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): TMP421 TMP422

Orderable Device Status(1) Package Type Package Drawing Pins Package Qty Eco Plan(2) Lead/Ball FinishMSL Peak Temp (3) TMP421AIDCNR ACTIVE SOT-23 DCN 8 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TMP421AIDCNRG4 ACTIVE SOT-23 DCN 8 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TMP421AIDCNT ACTIVE SOT-23 DCN 8 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TMP421AIDCNTG4 ACTIVE SOT-23 DCN 8 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TMP422AIDCNR ACTIVE SOT-23 DCN 8 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TMP422AIDCNRG4 ACTIVE SOT-23 DCN 8 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TMP422AIDCNT ACTIVE SOT-23 DCN 8 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TMP422AIDCNTG4 ACTIVE SOT-23 DCN 8 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR (1)The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2)Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontentfor the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS):TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt):This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br):TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. PACKAGE OPTION ADDENDUM www.ti.com 5-Oct-2007 Addendum-Page 1

TAPE AND REEL BOX INFORMATION Device Package Pins Site Reel Diameter (mm) Reel Width (mm) A0 (mm) B0 (mm) K0 (mm) P1 (mm) W (mm) Pin1 Quadrant TMP421AIDCNR DCN 8 SITE 48 179 8 3.2 3.2 1.4 4 8 Q1 TMP421AIDCNT DCN 8 SITE 48 179 8 3.2 3.2 1.4 4 8 Q1 TMP422AIDCNR DCN 8 SITE 48 179 8 3.2 3.2 1.4 4 8 Q1 TMP422AIDCNT DCN 8 SITE 48 179 8 3.2 3.2 1.4 4 8 Q1 PACKAGE MATERIALS INFORMATION www.ti.com 4-Oct-2007 Pack Materials-Page 1

Device Package Pins Site Length (mm) Width (mm) Height (mm) TMP421AIDCNR DCN 8 SITE 48 195.0 200.0 45.0 TMP421AIDCNT DCN 8 SITE 48 195.0 200.0 45.0 TMP422AIDCNR DCN 8 SITE 48 195.0 200.0 45.0 TMP422AIDCNT DCN 8 SITE 48 195.0 200.0 45.0 PACKAGE MATERIALS INFORMATION www.ti.com 4-Oct-2007 Pack Materials-Page 2

(TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI s terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI s standard warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily performed. TI assumes no liability for design. Customers are responsible for their products and components. To minimize the risks associated with customer products and applications, customers should provide adequate design and operating safeguards. TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right, or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the third party, or a license from TI under the patents or other intellectual property of TI. Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional restrictions. Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not responsible or liable for any such statements. TI products are not authorized for use in safety-critical (such as life support) where a failure of the TI product would reasonably be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be provided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in such safety-critical applications. TI products are neither designed nor intended for use in military/aerospace "enhanced plastic." Only products designated by TI as military-grade meet military specifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely at the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use. TI products are neither designed nor intended for use in automotive requirements. Buyers acknowledge and agree that, if they use any non-designated products in automotive applications, TI will not be responsible for any failure to meet such requirements. Following are URLs where you can obtain information on other Texas Instruments products and application solutions: Products amplifier.ti.com Audio www.ti.com/audio Data Converters dataconverter.ti.com Automotive www.ti.com/automotive DSP dsp.ti.com Broadband www.ti.com/broadband Interface interface.ti.com Digital Control www.ti.com/digitalcontrol Logic logic.ti.com Military www.ti.com/military Power Mgmt power.ti.com Optical Networking www.ti.com/opticalnetwork Microcontrollers microcontroller.ti.com Security www.ti.com/security RFID www.ti-rfid.com Telephony www.ti.com/telephony Low Power www.ti.com/lpw Video Imaging www.ti.com/video Wireless Wireless www.ti.com/wireless Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265 Copyright 2007, Texas Instruments Incorporated