DS1626 MAXIM | Alldatasheet
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DESCRIPTION
The DS1626 and DS1726 digital thermometers/thermostats provide temperature measurements 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 thermostatic functionality with three dedicated thermostat outputs (T HIGH, T LOW, and T COM), and overtemperature (TH) and undertemperature (T L) user-programmable thresholds stored in on-chip EEPROM. For stand-alone thermostat operation, TH and T L can be programmed prior to installation, and th e DS1626/DS1726 can be configured to automa tically begin taking temperature measurements at power-up. Table 1 summarizes the user-accessible registers. Figure 1 shows a functional diagram.
APPLICATIONS
Any Space-Constrained Thermally Sensitive Application
FEATURES
Temperature Measurements Require No External Components Measure Temperatures from -55°C to DS1626: ±0.5°C Accuracy from 0°C to +70°C DS1726: ±1°C Accuracy from -10°C to +85°C Output Resolution is User Selectable to 9, 10, 11, or 12 Bits Wide Power-Supply Range (2.7V to 5.5V) Convert Temperature to Digital Word in 750ms (max) Stand-Alone Thermostat Capability Thermostatic Settings are User Definable and Nonvolatile (NV) Data is Read/Written Through a 3-Wire Serial Interface Available in 8-Pin μSOP Package PIN CONFIGURATION
ORDERING INFORMATION
PART TEMP RANGE PIN-PACKAGE TOP MARK DS1626U -55°C to +125°C 8 μSOP 1626 DS1626U+ -55°C to +125°C 8 μSOP 1626 DS1626U/T&R -55°C to +125°C 8 μSOP, 3000-Piece 1626 DS1626U+T&R -55°C to +125°C 8 μSOP, 3000-Piece 1626 DS1726U -55°C to +125°C 8 μSOP 1726 DS1726U+ -55°C to +125°C 8 μSOP 1726 DS1726U/T&R -55°C to +125°C 8 μSOP, 3000-Piece 1726 DS1726U+T&R -55°C to +125°C 8 μSOP, 3000-Piece 1726 +Denotes a lead-free package. A “+” symbol will also be marked on the package near the Pin 1 indicator. T&R = Tape and reel. DS1626/DS1726 High-Precision 3-Wire Digital Thermometer and Thermostat www.maxim-ic.com CLK/CNV μSOP VDD THIGH TLOW TCOM GND RST DQ DS1626 DS1726 TOP VIEW
1 DQ Data Input/Output Pin (Tri-State ) for 3-Wire Serial Communication
measurements when the DS1626/DS1726 is configured as a stand-alone thermostat.
3 RST Reset Input Pin for 3-Wire Serial Communication
4 GND Ground Pin
5 T COM Thermostat Output Pin (Push-Pu ll) with Programmable Hysteresis
6 T LOW Thermostat Output Pin (Push-Pull) with T L Trip Point
7 T HIGH Thermostat Output Pin (Push-Pull) with T H Trip Point
8 V DD Supply Voltage. +2.7V to +5.5V input power pin. Table 1. DS1626/DS1726 REGISTER SUMMARY
1 Byte SRAM and
Figure 1. DS1626/DS1726 FUNCTIONAL DIAGRAM
These are stress ratings only and functional operation of the de vice at these or any other condi tions above those indicated in the operation sections of this specification is not im plied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. DC ELECTRICAL CHARACTERISTICS DD = 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 ≤ VDD ≤ 5.5V ±0.5 0°C to +70°C, 2.7V ≤ V DD < 3.0V ±1.25 DS1626 Thermometer Error (Note 2) T ERR -55°C to +125°C ±2 -10°C to +85°C, 3.0V ≤ VDD ≤ 5.5V -10°C to +85°C, 2.7V ≤ V DD < 3.0V ±1.5 DS1726 Thermometer Error (Note 2) T ERR -55°C to +125°C ±2 Low-Level Input Voltage V IL (Note 1) -0.5 0.3 x V DD V High-Level Input Voltage V IH (Note 1) 0.7 x V DD V DD + 0.3 V Input Current each Input Pin 0.4 < V I/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 mA Active Supply Current (Note 3) I DD E2 write 400 µA Input Resistance R I RST to GND DQ, CLK to VDD 1 MΩ Standby Supply Current I STBY 0°C to +70°C (Note 3) 1.5 µA VOH 1mA source current 2.4 THIGH, 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 4 10 ms 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 bits 93.75 10 bits 187.5 11 bits 375 Temperature Conversion Time t TC 12 bits 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 tRC (Note 5) 100 ns Clock to RST Hold tCRH (Note 5) 40 ns RST Inactive Time tRI (Note 7) 125 ns Clock High to I/O Hi-Z t CDZ (Note 5) 50 ns RST Low to I/O Hi-Z tRDZ (Note 5) 50 ns CNV Pulse Width tCNV (Note 8) 250ns 500ms I/O Capacitance C I/O 10 pF Input Capacitance C I 5 pF NOTES: 1) All voltages are referenced to ground. 2) See Figure 2 for TYPICAL OPERATING CURVES. 3) I STBY, 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 V DD and 0.3 x VDD. 6) Load capacitance = 50pF. 7) t RI 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.
in degrees Celsius; for Fahrenhe it applications a lookup table or conversion routine must be used. 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). Figure 4. TEMPERATURE, TH, and TL REGISTER FORMAT
Table 2. 12-BIT RESOLUTION TEMPERATURE/DATA RELATIONSHIP below TL. All three thermostat outputs are active-high outputs. bit (S). For the TCOM thermostat output to function correctly, the T L value must be less than the T H value. Any unused LSbs in the T H and T L registers are forced to 0 regardless of the data written to those bits. twelve are ignored (e.g., if two 8-bit words are written). set until the user overwrites it with a 0 or until the power is cycled.
determines if stand-alone mode is enabled. by using a microcontroller to transmit Start Convert T and Stop Convert T commands, respectively. performed after which the DS1626/DS1726 will return to a low-power idle state (i.e., one-shot operation). only the CLK/CNV signal determines whether continuous or one-shot conversions take place. command, they can only be stopped by issuing a Stop Convert T command. Figure 5. THERMOSTAT OUTPUT OPERATION
configuration register bits are SRAM. Figure 6. CONFIGURATION REGISTER Table 3. CONFIGURATION REGISTER BIT DESCRIPTIONS DONE = 0. Temperature conversion is in progress. DONE = 1. Temperature conversion is complete. power is cycled, or a Software POR command is issued. 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 4). Initial state from factory = 1. Power-up state = last value written to this bit. Sets conversion resolution (see Table 4). Initial state from factory = 1. Power-up state = last value written to this bit. CPU = 1. Stand-alone mode is disabled. 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. continuous temperature conversions. Initial state from factory = 0.
Table 4. RESOLUTION CONFIGURATION subsequent commands are recognized by the DS1626/DS1726. that these figures assume byte-wide data transfers. TH or Read TL command is used.
Figure 7. 3-WIRE COMMUNICATION
Maxim/Dallas Semiconductor cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim/Dallas Semiconductor product. No circuit patent licenses are implied. Maxim/Dallas Semiconductor reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2007 Maxim Integrated Products The Maxim logo is a registered trademark of Maxim Integrated Products, Inc. The Dallas logo is a registered trademark of Dallas Semiconductor Corporation. DS1626/DS1726 COMMAND SET The DS1626/DS1726 command set is detailed below: Start Convert T 51h 0101 0001 Initiates temperature conversions. If the DS1626/DS 1726 are in one-shot mode (1SHOT = 1), only one conversion will be performed. If the devices ar e 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 T H register. Write TL* 02h 0000 0010 Writes the 12-bit T L 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 should be requested for at least 10ms due to the EEPROM write cycle time.
PACKAGE INFORMATION
For the latest package outline information, go to www.maxim-ic.com/packages. PACKAGE TYPE PACKAG E CODE DOCUMENT NO. 8 μSOP — 21-0036