DS1726U

DS1626 DALLAS | Alldatasheet

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Technical content

FEATURES

/g167 Temperature Measurements Require No External Components /g167 Measure Temperatures from -55°C to +125°C (-67°F to +257°F) /g167 DS1626: /g1770.5°C Accuracy from 0°C to +70°C /g167 DS1726: /g1771°C Accuracy from -10°C to +85°C /g167 Output Resolution is User-Selectable to 9, 10, 11, or 12 Bits /g167 Wide Power-Supply Range (2.7V to 5.5V) /g167 Convert Temperature to Digital Word in 750ms (max) /g167 Stand-Alone Thermostat Capability /g167 Thermostatic Settings are User-Definable and Nonvolatile (NV) /g167 Data is Read/Written Through a 3-Wire Serial Interface /g167 Available in 8-Pin /g109MAX//g109SOP Package PIN CONFIGURATION

DESCRIPTION

The DS1626 and DS1726 digital thermometers/thermostat s provide temperature m easurements and stand- alone thermostat capability over a -55°C to +125°C range. The DS1626 offers ±0.5°C accuracy from 0°C to +70°C and the DS1726 has ±1°C accuracy from -10° C to +85°C. The resolution of the measured temperature is user-selectable from 9 to 12 bits . Communication with the DS1626 and DS1726 is achieved through a 3-wire serial bus. The DS1626 and DS1726 offer thermost atic functionality with three dedicated thermostat outputs (T HIGH, TLOW, and T COM), and over-temperature (T H) and under-temperature (T L) user-programmable thresholds stored in on-chip EEPROM. For st and-alone thermostat operation, T H and T L can be programmed prior to installation, and the DS1626/DS1726 can be configured to automatically begin taking temperature measurements at power-up. Pin descriptions for the DS1626 a nd DS1726 are provided in Table 2 a nd user-accessible registers are summarized in Table 3. A functional diagram is shown in Figure 1. DS1626/DS1726 High-Precision 3-Wire Digital Thermometer and Thermostat www.maxim-ic.com /g109SOP (DS1626U, DS1726U) CLK/CNV VDD THIGH TLOW TCOMGND RST DQ See Table 1 for Ordering Information See Table 2 for Pin Descriptions

APPLICATIONS

/g167 Thermostatic Controls /g167 Industrial Controls /g167 Consumer Products /g167 Any Space-Constrained Thermally Sensitive Application

ORDERING INFORMATION

PART PACKAGE MARKING DESCRIPTION DS1626U D1626 8-Pin /g109SOP DS1626U/T&R D1626 8-Pin /g109SOP, 3000-Piece Tape-and-Reel DS1726U D1726 8-Pin /g109SOP DS1726U/T&R D1726 8-Pin /g109SOP, 3000-Piece Tape-and-Reel Table 2. DETAILED PIN DESCRIPTION

3 RST Reset Input Pin for 3-Wire Serial Communication

4 GND Ground Pin

Table 3. DS1626/DS1726 REGISTER SUMMARY Power-Up/POR State: User-Defined. Power-Up/POR State: User-Defined.

1 Byte SRAM and

Figure 1. DS1626/DS1726 FUNCTIONAL DIAGRAM

ABSOLUTE MAXIMUM RATINGS* Voltage on Any Pin Relative to Ground -0.5V to +6.0V Operating Temperature Range -55°C to +125°C Storage Temperature Range -55°C to +125°C Solder Dip Temperature (10s) +260°C Reflow Oven Temperature +220°C * These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. DC ELECTRICAL CHARACTERISTICS (VDD = 2.7V to 5.5V; TA = -55°C to +125°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Supply Voltage V DD (Note 1) 2.7 5.5 V 0°C to +70°C, 3.0V /g163 VDD /g163 5.5V ±0.5 0°C to +70°C, 2.7V /g163 VDD /g60 3.0V ±1.25 DS1626 Thermometer Error (Note 2) T ERR -55°C to +125°C ±2 -10°C to +85°C, 3.0V /g163 VDD /g163 5.5V ±1 -10°C to +85°C, 2.7V /g163 VDD /g60 3.0V ±1.5 DS1726 Thermometer Error (Note 2) T ERR -55°C to +125°C ±2 Low-Level Input Voltage VIL (Note 1) -0.5 0.3 x V DD V High-Level Input Voltage VIH (Note 1) 0.7 x V DD VDD + 0.3 V Input Current each Input Pin 0.4 < VI/O < 0.9 x VDD -10 +10 µA Temperature conversion -55°C to +85°C 1 Temperature conversion +85°C to +125°C 1.25 mAActive Supply Current (Note 3) IDD E2 write 400 µA Input Resistance R I RST to GND DQ, CLK to VDD

1 M/g87

Current ISTBY 0°C to +70°C (Note 3) 1.5 µA VOH 1mA source current 2.4THIGH, TLOW, TCOM, DQ Output Logic Voltages (Note 1) V OL 4mA sink current 0.4 V Thermal Drift (Note 4) ±0.2 °C

EEPROM AC ELECTRICAL CHARACTERISTICS (VDD = 2.7V to 5.5V; TA = -55°C to +125°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS EEPROM Write Cycle Time t wr 41 0m s EEPROM Writes N EEWR -55°C to +55°C 50k Writes EEPROM Data Retention t EEDR -55°C to +55°C 10 Years AC ELECTRICAL CHARACTERISTICS (VDD = 2.7V to 5.5V; TA = -55°C to +125°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 9-bit 93.75 10-bit 187.5 11-bit 375Temperature Conversion Time t TC 12-bit 750 ms Data In to Clock Setup t DC (Note 5) 35 ns Clock to Data In Hold t CDH (Note 5) 40 ns Clock to Data Out Delay t CDD (Notes 5, 6) 150 ns Clock Low/High Time t CL, tCH (Note 5) 285 ns Clock Frequency f CLK (Note 5) 0 1.75 MHz Clock Rise/Fall Time t R, tF (Note 5) 500 ns RST to Clock Setup t RC (Note 5) 100 ns Clock to RST Hold tCRH (Note 5) 40 ns RST Inactive Time t RI (Note 7) 125 ns Clock High to I/O Hi-Z t CDZ (Note 5) 50 ns RST Low to I/O Hi-Z t RDZ (Note 5) 50 ns CNV Pulse Width t CNV (Note 8) 250ns 500ms I/O Capacitance C I/O 10 pF Input Capacitance C I 5p F NOTES: 1) All voltages are referenced to ground. 2) See Figure 2 for TYPICAL OPERATING CURVES. 3) ISTBY, IDD specified with DQ, CLK/CNV = VDD and RST = GND. 4) Drift data is based on a 1000hr stress test at +125°C with VDD = 5.5V. 5) See Timing Diagrams in Figure 3. All timing is referenced to 0.7 x VDD and 0.3 x VDD. 6) Load capacitance = 50pF. 7) tRI must be 10ms minimum following any write command that involves the E2 memory. 8) 250ns is the guaranteed minimum pulse width for a conversion to start, however, a smaller pulse width may start a conversion.

all data is transmitted LSb first. temperature measurement to be taken and then the DS1626/DS1726 return to a low-power idle state. conversion time doubles for each additional bit of resolution. measured temperature as a two’s complement number in the 12-bit temperature register (see Figure 4). data and the corresponding temperatures. Figure 4. TEMPERATURE, TH, and TL REGISTER FORMAT

Table 4. 12-BIT RESOLUTION TEMPERATURE/DATA RELATIONSHIP is asserted when the temperature is equal to or falls below the value in the T L register (see Figure 5). below TL. All three thermostat outputs are active-high outputs. lost. Any additional bits sent after the first twelve are ignored (e.g., if two 8-bit words are written). remain set until the user overwrites it with a 0 or until the power is cycled.

CPU BIT AND STAND-ALONE THERMOSTAT OPERATION In stand-alone thermostat mode, DS1626/DS1726 th ermostat functionality can be used without requiring a microcontroller to start/stop temperature conversions. The CPU bit in the configuration register determines if stand-alone mode is enabled. When CPU = 1 stand-alone mode is disabled, and the only way to start/stop temperature conversions is by using a microcontroller to transmit Start Convert T and Stop Convert T commands, respectively. Stand-alone mode is enabled when CPU = 0. In this mode, when RST = 0 the CLK/ CNV pin operates as a control signal to start and stop temperature measurements. Driving CLK/ CNV low initiates continuous temperature conversions that will continue until CLK/ CNV is brought high again. If the CLK/CNV pin is driven low and then returned to a high state in less than 10ms, only one temperature conversion will be perfor med after which the DS1626/DS1726 will re turn to a low-power idle state (i.e., one-shot operation). Note that when stand- alone mode is enabled, the 1SHOT bit in the configuration register is ignored, and only the CLK/ CNV signal determines whether continuous or one-shot conversions take place. Since T H, TL, and the CPU bit are stored in EEPROM, the DS1626/DS1726 can be preprogrammed for stand-alone operation. If desired, the CLK/ CNV and RST pin can be connected to GND so the DS1626/DS1726 will automatically begin taking temperature measurements at power-up Normal bus communication with the DS1626/DS1726 can still take pl ace in stand-alone mode when RST = 1. When communication is initiated, stand-alone conversions are automatically halted. If during the bus communication continuous temperature conve rsions are started using the Start Convert T command, they can only be stopped by issuing a Stop Convert T command.

Table 5. CONFIGURATION REGISTER BIT DESCRIPTIONS DONE = 0. Temperature conversion is in progress. DONE = 1. Temperature conversion is complete. the power is cycled, or a Software POR command is issued. the user, the power is cycled, or a Software POR command is issued. 2 memory cell is in progress. NVB = 0. NV memory is not busy. Power-up state = last value written to this bit. Sets conversion resolution (see Table 6). Initial state from factory = 1. Power-up state = last value written to this bit. Sets conversion resolution (see Table 6). Initial state from factory = 1. Power-up state = last value written to this bit. CPU = 1. Stand-alone mode is disabled. STAND-ALONE THERMOSTAT OPERATION section for more information. Initial state from factory = 0. Power-up state = last value written to this bit. temperature conversion and then the device goes into a low-power standby state. initiates continuous temperature conversions. Initial state from factory = 0. Table 6. RESOLUTION CONFIGURATION

The 3-wire bus consists of three signals: RST (reset—active low), CLK (clock), and DQ (data). 3-wire communication is controlled by the RST signal, which functions as “chip select” signal. All data is transferred LSb first over the 3-wire bus. All communication with the DS1626/DS1726 is initiated by driving RST high. Driving RST low terminates communications and causes DQ to go to a high- impedance state. Note that RST must be toggled low after every communication sequence to ensure that subsequent commands are recognized by the DS1626/DS1726. When writing to the DS1626/DS1726, data must be valid during the rising edge of CLK. During read operations the DS1626/DS1726 output da ta on DQ on the falling edge of CLK and the data remains valid through the following rising edge, at which time the DQ pin becomes high impedance until the next falling edge. To communicate with the DS1626/DS1726, the master must first drive RST high and then begin generating the CLK signal while transmitting the desired DS1626/DS1726 command byte. If the command is a Start Convert T, Stop Convert T, or Software POR command, the transaction is finished when the last bit of the command has been sent . Figure 7a illustrates a Start Convert T command sequence. When writing to the DS1626/DS1726, the master must begin transmitting data during the clock cycle immediately following the command byte. The DS1626/DS1726 will save only the number of data bits needed for the specific transaction. For example, for the Write TH or Write TL commands, after twelve bits of data have been transmitted by the master, the DS1626/DS1726 will ignore any subsequent data transmitted before RST goes low. Thus, if data is being transmitted in byte-length segments, the DS1626/DS1726 will load the first twelve bits into the T H/TL register, and the next four bits will be ignored. On the other hand, it is necessary to transmit at least the required number of bits for the requested transaction (i.e., 12-bits to T H/TL or 8-bits to the configuration register), because the DS1626/DS1726 will not save data until the expected number of bits have been received. Write TH and Write TL sequences are illustrated in Figure 7b and a Write Config sequence is shown in Figure 7c. Note that these figures assume byte-wide data transfers. When reading data from the DS1626/DS1726, the DS 1626/DS1726 will begin sending data during the clock cycle immediately following the command byte. After the last data byte has been sent, the DS1626/DS1726 will transmit a 0 during each subsequent clock until RST goes low. Figure 7d illustrates a Read Temperature sequence and a Read Config transaction is shown in Figure 7e. The sequence for reading the T H or T L registers is the same as the Read Temp transaction in Figure 7d except that the Read TH or Read TL command is used.

Figure 7. 3-WIRE COMMUNICATION

The DS1626/DS1726 command set is detailed below: Start Convert T 51h 0101 0001 Initiates temperature conversions. If the DS1626/DS1726 are in one-shot mode (1SHOT = 1), only one conversion will be perfor med. If the devices are in continuous mode (1SHOT = 0), continuous conversions will be performed until a Stop Convert T command is issued. Stop Convert T 22h 0010 0010 Stops temperature conversions when the devices are in continuous conversion mode (1SHOT = 0). Read Temperature AAh 1010 1010 Reads the last converted temperature value from the temperature register. Read TH A1h 1010 0001 Reads the 12-bit TH register. Read TL A2h 1010 0010 Reads the 12-bit TL register. Write TH* 01h 0000 0001 Writes the 12-bit TH register. Write TL* 02h 0000 0010 Writes the 12-bit TL register. Read Config ACh 1010 1100 Reads the 1-byte configuration register. Write Config* 0Ch 0000 1100 Writes the 1-byte configuration register. Software POR 54h 0101 0100 Initiates a software power-on reset (POR), which stops temperature conversions and resets all registers and logic to their power-up states. The software POR allows the user to simulate cycling the power without actually powering down the device. *After issuing a write command, no further writes s hould be requested for at least 10ms due to the EEPROM write cycle time.