MAX6649:+145°C Precision SMBus-Compatible Remote/Local Sensors with Overtemperature Alarms

The MAX6646/MAX6647/MAX6649 are precise, two-channel digital temperature sensors. The devices accurately measure the temperature of their own die and a remote PN junction, and report the temperature in digital form using a 2-wire serial interface. The remote PN junction is typically the emitter-base junction of a common-collector PNP on a CPU, FPGA, or ASIC. 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 to program the alarm thresholds. To enhance system reliability, the MAX6646/MAX6647/MAX6649 include an SMBus timeout. A fault queue prevents the active-low ALERT and active-low OVERT outputs from setting until a fault has been detected one, two, or three consecutive times (programmable). The MAX6646/MAX6647/MAX6649 provide two system alarms: active-low ALERT and active-low OVERT. Active-low ALERT asserts when any of four temperature conditions are violated: local overtemperature, remote overtemperature, local undertemperature, or remote undertemperature. Active-low OVERT asserts when the temperature rises above the value in either of the two active-low OVERT limit registers. The active-low OVERT output can be used to activate a cooling fan, or to trigger a system shutdown. Measurements can be done autonomously, at the programmed conversion rate, or in a single-shot mode. The adjustable conversion rate allows optimizing supply current and temperature update rate to match system needs. Remote accuracy is ±1°C maximum error between +60°C and +145°C with no calibration needed. The MAX6646/MAX6647/MAX6649 operate from -55°C to +125°C, and measure temperatures between 0°C and +145°C. The MAX6646/MAX6647/MAX6649 are available in an 8-pin µMAX® package.

Key Features
  • Dual Channel: Measures Remote and Local Temperature
  • 0.125°C Resolution
  • High Accuracy ±1°C (max) from +60°C to +145°C (Remote), and ±2°C (max) from +60°C to +100°C (Local)
  • Measures High-Ideality Thermal Diodes Up to
    • +170°C (Apparent)
    • +145°C (Real)
  • Two Alarm Outputs: Active-Low ALERT and Active-Low OVERT
  • Programmable Under/Overtemperature Alarm Temperature Thresholds
  • Programmable Conversion Rate
  • SMBus-Compatible Interface
  • SMBus Timeout
MAX6646, MAX6647, MAX6649: Typical Operating Circuit
MAX6646, MAX6647, MAX6649: Typical Operating Circuit
Applications/Uses
  • Desktop Computers
  • Graphics Processors
  • Multichip Modules
  • Notebook Computers
  • Servers
  • Test and Measurement Equipment
  • Thin Clients
  • Workstations
DataSheet
titleDownload file
MAX6646-MAX6649 Data SheetMAX6646-MAX6649.pdf
Parametrics
Part NumberSensor TypeAlarm OutputFunctionsInterfaceChannelsAccuracy
(±°C)
Parasite Pwr.Temp. Thresh.Temp. Resolution
(bits)
Oper. Temp.
(°C)
Package/PinsBudgetary
Price
See Notes
MAX6646RemoteAlert
Overt
Dual Temperature Alarms
Remote & Local Sensor
2-Wire/I2C/SMBusOne0.8NoProgrammable11-55 to +125µMAX/8$1.67 @1k
MAX6647µMAX/8$1.67 @1k
MAX6649µMAX/8$2.08 @1k
Quality and Environmental Data
Related Products
  • MAX6648:Precision SMBus-Compatible Remote/Local Temperature Sensors with Overtemperature Alarms
  • MAX6692:Precision SMBus-Compatible Remote/Local Temperature Sensors with Overtemperature Alarms
Ordering Information
Part NumberStatusRecommended ReplacementPackageTempRoHS
MAX6649MUANo Longer AvailableMAX6649MUA+µMAX,;8 pin;15.6 mm²-40°C to +85°CNo
MAX6649MUA+ActiveµMAX,;8 pin;15.6 mm²-55°C to +125°CLead Free
MAX6649MUA+TActiveµMAX,;8 pin;15.6 mm²-40°C to +85°CLead Free
MAX6649MUA-G002No Longer AvailableuMAX;-40°C to +85°CSee data sheet
MAX6649MUA-TNo Longer AvailableMAX6649MUA+TµMAX,;8 pin;15.6 mm²-40°C to +85°CNo
MAX6649MUA-TG002No Longer AvailableuMAX;-40°C to +85°CSee data sheet
MAX6649YMUA+ActiveµMAX,;8 pin;15.6 mm²-40°C to +85°CLead Free
MAX6649YMUA+TActiveuMAX;8 pin-40°C to +85°CSee data sheet
MAX6646-MAX6649.pdf MAX6649
Effect of PC Board Trace Width on Remote-Diode Temperature-Sensor Accuracy MAX6698
Compensating for Ideality Factor and Series Resistance Differences between Thermal-Sense Diodes MAX6699
MAX6649.pdf MAX6649
MAX6646-MAX6649.pdf MAX6647