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

Product Details

Key Features

Applications/Uses

Simplified Block Diagram

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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

Applications/Uses

  • Communication Systems
  • Computers: Desktop, Workstation, Server
  • Notebook Computers
  • Servers
  • Thin Clients
  • Workstations

Description

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.

Simplified Block Diagram

MAX6655, MAX6656: Typical Application Circuit MAX6655, MAX6656: Typical Application Circuit Zoom icon

Support & Training

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Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .