±1°C Fail-Safe Remote/Local Temperature Sensors with SMBus Interface

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The MAX6680/MAX6681 are precise, two-channel digital thermometers. Each accurately measures the temperature of its own die and one remote PN junction and reports the temperature on a 2-wire serial interface. The remote junction can be a diode-connected transistor like the low-cost NPN type 2N3904 or PNP type 2N3906. The remote junction can also be a common-collector PNP, such as a substrate PNP of a microprocessor.

The MAX6680/MAX6681 include pin-programmable default temperature thresholds for the active-low OVERT output, which provides fail-safe clock throttling or system shutdown. In addition, the devices are pin programmable to select whether the active-low OVERT output responds to either the local, remote, or both temperatures.

The 2-wire serial interface accepts standard System Management Bus (SMBus™) commands such as Write Byte, Read Byte, Send Byte, and Receive Byte to read the temperature data and program the alarm thresholds and conversion rate. The MAX6680/MAX6681 can function autonomously with a programmable conversion rate, which allows the control of supply current and temperature update rate to match system needs. For conversion rates of 4Hz or less, the remote sensor temperature can be represented in extended mode as 10 bits + sign with a resolution of 0.125°C. When the conversion rate is 8Hz, output data is 7 bits + sign with a resolution of 1°C. The MAX6680/MAX6681 also include an SMBus timeout feature to enhance system reliability.

The MAX6681 is an upgrade to the MAX6654. The MAX6680/MAX6681 remote accuracy is ±1°C with no calibration needed. They are available in a 16-pin QSOP package and operate throughout the -55°C to +125°C temperature range.

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MAX6680, MAX6681: Typical Operating Circuit MAX6680, MAX6681: Typical Operating Circuit Enlarge+

Key Features

  • Two Alarm Outputs: Active-Low ALERT and Active-Low OVERT
  • Pin-Programmable Threshold for Active-Low OVERT Limit
  • Programmable Under/Overtemperature Active-Low ALERT Limit
  • Dual Channel: Measures Remote and Local Temperature
  • 11-Bit, 0.125°C Resolution for Remote Temperature Measurements
  • High Accuracy ±1°C (max) from +60°C to +100°C (Remote)
  • No Calibration Required
  • SMBus/I²C-Compatible Interface
  • SMBus Timeout Prevents SMBus Lockup


  • Desktop Computers
  • Notebook Computers
  • Servers
  • Thin Clients
  • Workstations

See parametric specs for Temperature Sensors (113)

Part NumberSensor TypeAlarm OutputFunctionsInterface#ChannelsAccuracy
Parasite Pwr.Temp. Thresh.Temp. Resolution
Multi DroppableOper. Temp.
(See Notes)
MAX6680 Remote
Fan Controller
Remote & Local Sensor
2-Wire/I2C/SMBusOne1NoProgrammable11Yes-55 to +125
$3.99 @1k

Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

MAX6681EVKIT: Evaluation System/Evaluation Kit for the MAX6681
Product Reliability Reports: MAX6681.pdf 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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