MAX6655:Dual Remote/Local Temperature Sensors and Four-Channel Voltage Monitors

The MAX6655/MAX6656 are precise voltage and temperature monitors. The digital thermometer reports the temperature of two remote sensors and its own die temperature. The remote sensors are diode-connected transistors—typically a low-cost, easily mounted 2N3906 PNP type—that replace conventional thermistors or thermocouples. Remote accuracy is ±1°C for multiple transistor manufacturers with no calibration necessary. The remote channels can also measure the die temperature of other ICs, such as microprocessors, that contain a substrate-connected PNP with its collector grounded and its base and emitter available for temperature-sensing purposes. The temperature is digitized with 11-bit resolution. The MAX6655/MAX6656 also measure their own supply voltage and three external voltages with 8-bit resolution. Each voltage input's sensitivity is set to give approximately 3/4-scale output code when the input voltage is at its nominal value. The MAX6655 operates at +5V supply and its second voltage monitor is 3.3V. The MAX6656 operates on a +3.3V supply and its second voltage monitor is 5V. The 2-wire serial interface accepts standard SMBus™ Write Byte, Read Byte, Send Byte, and Receive Byte commands to program the alarm thresholds and to read data. The MAX6655/MAX6656 also provide SMBus alert response and timeout functions. The MAX6655/MAX6656 measure automatically and autonomously, with the conversion rate programmable. The adjustable rate allows the user to control the supply current. In addition to the SMBus active-low ALERT output, the MAX6655/MAX6656 feature an active-low OVERT output, which is used as a temperature reset that remains active only while the temperature is above the maximum temperature limit. The active-low OVERT output is optimal for fan control or for system shutdown.

Key Features
  • Three Temperature Channels
    • Two Remote PN Junctions
    • One Local Sensor
  • Four Voltage Channels
    • +12V, +5V, +3.3V, +2.5V
    • Three External Monitors
    • One Internal Supply Monitor
  • 11-Bit, 0.125°C Resolution
  • High Accuracy: ±1°C Over +60°C to +100°C Temperature Range
  • Programmable Under/Over-Threshold Alarms
  • Programmable Power-Saving Mode
  • No Calibration Required
  • SMBus/I²C-Compatible Interface
  • Active-low OVERT Output for Fan Control and System Shutdown
MAX6655, MAX6656: Typical Application Circuit
MAX6655, MAX6656: Typical Application Circuit
Applications/Uses
  • Communication Systems
  • Computers: Desktop, Workstation, Server
  • Notebook Computers
  • Servers
  • Thin Clients
  • Workstations
DataSheet
titleDownload file
MAX6655-MAX6656 Data SheetMAX6655-MAX6656.pdf
Parametrics
Part NumberSensor TypeAlarm OutputFunctionsInterfaceChannelsAccuracy
(±°C)
Parasite Pwr.Temp. Thresh.Temp. Resolution
(bits)
Multi DroppableOper. Temp.
(°C)
Package/PinsBudgetary
Price
See Notes
MAX6655RemoteAlert
Overt
Remote & Local Sensor
Voltage Monitor
2-Wire/I2C/SMBusTwo1NoProgrammable11Yes-55 to +125QSOP/16$3.01 @1k
MAX6656QSOP/16
Design kits & evaluation modules
Quality and Environmental Data
Ordering Information
Part NumberStatusRecommended ReplacementPackageTempRoHS
MAX6655MEENo Longer AvailableMAX6655MEE+QSOP,;16 pin;30.9 mm²0°C to +70°CNo
MAX6655MEE+ActiveQSOP,;16 pin;30.9 mm²-55°C to +125°CLead Free
MAX6655MEE+TActiveQSOP,;16 pin;30.9 mm²0°C to +70°CLead Free
MAX6655MEE-TNo Longer AvailableMAX6655MEE+TQSOP;16 pin0°C to +70°CSee data sheet
MAX6655-MAX6656.pdf MAX6656
Understanding Multidrop Address Assignments for Thermal Sensors MAX7504
Compensating for Ideality Factor and Series Resistance Differences between Thermal-Sense Diodes MAX6699
Protect a System from Overheating by Monitoring Board, CPU, and Air Temperatures with a Single Circuit MAX6656
MAX6655.pdf MAX6655
MAX6655-MAX6656.pdf MAX6656