This low-voltage (1.7V to 3.7V) digital thermometerand thermostat provides 9, 10, 11, or 12-bit digitaltemperature readings over a -55°C to +125°C rangewith ±2°C accuracy over a -25°C to +100°C range. Atpower-up, the DS75LX defaults to 9-bit resolution forsoftware compatibility with the LM75. Communicationwith the DS75LX is achieved through a simple 2-wireserial interface. Three tri-state address pins allow upto 27 DS75LX devices to operate on the same 2-wirebus, which greatly simplifies distributed temperature-sensingapplications.The DS75LX thermostat has a dedicated open-drainoutput (O.S.) and programmable fault tolerance,which allow the user to define the number ofconsecutive error conditions that must occur beforeO.S. is activated. There are two thermostaticoperating modes that control thermostat operationbased on user-defined trip-points (TOS and THYST).ApplicationsAny Thermally Sensitive SystemCellular Base StationsServersTelecom Switches and Routers

The MAX31722/MAX31723 digital thermometers and thermostats with an SPI/3-wire interface provide temperature readings that indicate the device temperature. No additional components are required; the devices are truly temperature-to-digital converters. Temperature readings are communicated from the device over an SPI interface or a 3-wire serial interface. The choice of interface is selectable by the user. For applications that require greater temperature resolution, the user can adjust the readout resolution from 9 to 12 bits. This is particularly useful in applications where thermal runaway conditions must be detected quickly. The thermostat has a dedicated open-drain output (active-low TOUT). Two thermostat operating modes, comparator and interrupt, control thermostat operation based on user-defined nonvolatile trip points (THIGH and TLOW). Both devices feature a 1.7V to 3.7V supply rail.ApplicationsAny Thermally Sensitive SystemsCellular Base StationsIndustrial EquipmentNetworking Equipment

The MAX6581 precision multichannel temperature sensor monitors its own temperature and the temperatures of up to seven external diode-connected transistors. All temperature channels have programmable alert and overtemperature thresholds. When the measured temperature of a channel crosses the respective threshold, a status bit is set in one of the status registers. Two open-drain alarm outputs (active-low ALERT and active-low OVERT) assert corresponding to these bits in the status register(s). Resistance cancellation is available for all channels and compensates for high series resistance in circuit-board traces and thermal diodes. The 2-wire serial interface accepts SMBus protocols (write byte, read byte, send byte, and receive byte) for reading the temperature data and programming the alarm thresholds. The MAX6581 is specified for an operating temperature range of -40°C to +125°C and is available in a 24-pin, 4mm × 4mm thin QFN package with an exposed pad.ApplicationsData CommunicationsDesktop ComputersNotebook ComputersServersWorkstations

The MAX31820 ambient temperature sensor provides 9-bit to 12-bit Celsius temperature measurements with ±0.5°C accuracy over a +10°C to +45°C temperature range. Over its entire -55°C to +125°C operating range, the device has ±2.0°C accuracy. The device communicates over a 1-Wire® bus that, by definition, requires only one data line (and ground) for communication with a central microprocessor. In addition, the device can derive power directly from the data line (“parasite power”), eliminating the need for an external power supply. Requiring so few pins enables the device to be placed in a 3-pin TO-92 package. The form factor of this package allows the device to be placed above the board and thus measure the ambient temperature of a system, as opposed to the board temperature that a surface-mount package would measure. Each MAX31820 has a unique 64-bit serial code, which allows multiple MAX31820 devices to function on the same 1-Wire bus. Therefore, it is simple to use one microprocessor to control many devices distributed over a large area.ApplicationsAny Thermally Sensitive SystemConsumer ProductsHVAC Environmental ControlsIndustrial SystemsProcess Monitoring and Control SystemsTemperature Monitoring Systems Inside Buildings, Equipment, or MachineryThermometersThermostatic Controls

The MAX6639 monitors its own temperature and one external diode-connected transistor or the temperatures of two external diode-connected transistors, typically available in CPUs, FPGAs, or GPUs. The 2-wire serial interface accepts standard System Management Bus (SMBus) write byte, read byte, send byte, and receive byte commands to read the temperature data and program the alarm thresholds. Temperature data can be read at any time over the SMBus, and three programmable alarm outputs can be used to generate interrupts, throttle signals, or overtemperature shutdown signals.The temperature data is also used by the internal dual-PWM fan-speed controller to adjust the speed of up to two cooling fans, thereby minimizing noise when the system is running cool, but providing maximum cooling when power dissipation increases. Speed control is accomplished by tachometer feedback from the fan, so that the speed of the fan is controlled, not just the PWM duty cycle. Accuracy of speed measurement is ±4%.The MAX6639 is available in 16-pin QSOP and 16-pin thin QFN 5mm x 5mm packages. It operates from 3.0V to 3.6V and consumes just 500µA of supply current.ApplicationsDesktop ComputersNetworking EquipmentNotebook ComputersProjectorsServers

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 (THIGH, TLOW, and TCOM), and overtemperature (TH) and undertemperature (TL) user-programmable thresholds stored in on-chip EEPROM. For stand-alone thermostat operation, TH and TL can be programmed prior to installation, and the DS1626/DS1726 can be configured to automatically begin taking temperature measurements at power-up. Table 1, in the full data sheet, summarizes the user-accessible registers. Figure 1, in the full data sheet, shows a functional diagram.ApplicationsAny Space-Constrained Thermally Sensitive ApplicationConsumer ProductsIndustrial ControlsThermostatic Controls

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 (THIGH, TLOW, and TCOM), and overtemperature (TH) and undertemperature (TL) user-programmable thresholds stored in on-chip EEPROM. For stand-alone thermostat operation, TH and TL can be programmed prior to installation, and the DS1626/DS1726 can be configured to automatically begin taking temperature measurements at power-up. Table 1, in the full data sheet, summarizes the user-accessible registers. Figure 1, in the full data sheet, shows a functional diagram.ApplicationsAny Space-Constrained Thermally Sensitive ApplicationConsumer ProductsIndustrial ControlsThermostatic Controls

The DS1631, DS1631A, and DS1731 digital thermometers provide 9, 10, 11, or 12-bit temperature readings over a -55°C to +125°C range. The DS1631 and DS1631A thermometer accuracy is ±0.5°C from 0°C to +70°C with 3.0V ≤ VDD ≤ 5.5V, and the DS1731 accuracy is ±1°C from -10°C to +85°C with 3.0V ≤ VDD ≤ 5.5V. The thermostat on all three devices provides custom hysteresis with user-defined trip points (TH and TL). The TH and TL registers and thermometer configuration settings are stored in NV EEPROM so they can be programmed prior to installation. In addition, the DS1631A automatically begins taking temperature measurements at power-up, which allows it to function as a stand-alone thermostat.ApplicationsMedicalNetworkingPersonal ComputingRouters/SwitchesTest Measurement SystemsWireless Base Stations

The DS1775 digital thermometer and thermostatprovides temperature readings that indicate the device’stemperature. Thermostat settings and temperaturereadings are all communicated to/from the DS1775 overa simple 2-wire serial interface. No additional componentsare required; the device is truly a “temperature-to-digital”converter.For applications that require greater temperature resolution,the user can adjust the readout resolution from 9 to 12bits. This is particularly useful in applications wherethermal runaway conditions must be detected quickly.The open-drain thermal alarm output, O.S., becomesactive when the temperature of the device exceeds auser-defined temperature TOS. The number of consecutivefaults required to set O.S. active is configurable by theuser. The device can also be configured in the interrupt orcomparator mode, to customize the method which clearsthe fault condition.As a digital thermometer, the DS1775 is software compatiblewith the DS75 2-wire thermal watchdog. The DS1775 isassembled in a compact 5-pin SOT23 package, allowingfor low-cost thermal monitoring/control in spaceconstrainedapplications. The low thermal mass allows fortime constants previously only possible with thermistors.ApplicationsAny Thermally-Sensitive SystemCell PhonesOffice EquipmentPersonal Computers/Servers/Workstations

The DS1775 digital thermometer and thermostatprovides temperature readings that indicate the device’stemperature. Thermostat settings and temperaturereadings are all communicated to/from the DS1775 overa simple 2-wire serial interface. No additional componentsare required; the device is truly a “temperature-to-digital”converter.For applications that require greater temperature resolution,the user can adjust the readout resolution from 9 to 12bits. This is particularly useful in applications wherethermal runaway conditions must be detected quickly.The open-drain thermal alarm output, O.S., becomesactive when the temperature of the device exceeds auser-defined temperature TOS. The number of consecutivefaults required to set O.S. active is configurable by theuser. The device can also be configured in the interrupt orcomparator mode, to customize the method which clearsthe fault condition.As a digital thermometer, the DS1775 is software compatiblewith the DS75 2-wire thermal watchdog. The DS1775 isassembled in a compact 5-pin SOT23 package, allowingfor low-cost thermal monitoring/control in spaceconstrainedapplications. The low thermal mass allows fortime constants previously only possible with thermistors.ApplicationsAny Thermally-Sensitive SystemCell PhonesOffice EquipmentPersonal Computers/Servers/Workstations