MAX6644LBAAEE+T

Thermal Management Overview

The MAX6644LBAAEE+T is an automatic PWM fan-speed controller and temperature monitor from Analog Devices/Maxim Integrated. It operates within a supply voltage range of +3.0V to +5.5V, consuming a typical operating current of 500µA. The device measures temperatures at two external diode-connected transistors with a conversion time of 125ms. It features pin-selectable high-temperature (THIGH) and low-temperature (TLOW) thresholds in 5°C increments. The unit generates a 32Hz PWM output waveform to drive an external power transistor for fan speed modulation. It includes an active-low overtemperature output (OT) and a FANFAIL alarm output. The component is housed in a 16-pin QSOP package and functions across an operating temperature range of -40°C to +125°C.

Thermal Management Feature Summary

• Automatically adjusts fan speed via PWM output based on remote temperature measurements to optimize cooling while minimizing acoustic noise.
• Monitors temperatures of one or two external diode-connected transistors using integrated pn junction-based sensors.
• Detects fan failure through locked-rotor logic, tachometer signals, or fan-supply current sensing via configurable FAN_IN inputs.
• Provides selectable trip temperatures for both high and low fan control thresholds and an overtemperature fault output.

Thermal Management Applications

• Networking Equipment
• Storage Equipment
• Servers
• Desktop Computers
• Workstations

Thermal Management Procurement Notes

Verify the specific suffix 'LBAAEE' against official documentation to confirm pin configuration and factory settings. Ensure the ordering code matches the required 16-pin QSOP package variant. Confirm that the application circuit supports the 3.0V to 5.5V supply range and utilizes appropriate external components for the PWM driver and remote diode connections as specified in the datasheet.

Thermal Management Selection Notes

Select this component when dual remote temperature monitoring is required alongside automatic fan speed regulation. It is suitable for systems needing pin-selectable thermal thresholds rather than fixed factory-programmed values found in other variants. Consider its compatibility with external N-channel MOSFETs or NPN transistors for driving fans. Evaluate the need for its specific fan-fail detection capabilities compared to simpler single-channel controllers.

Thermal Management Part Context

This part belongs to the MAX6643/MAX6644/MAX6645 family of automatic PWM fan-speed controllers. Unlike the MAX6643 which monitors internal die temperature, the MAX6644 focuses exclusively on external diode-connected transistors. It shares the same 16-pin QSOP package and electrical characteristics as the MAX6643 but differs in sensor channel configuration. The MAX6645 offers similar functionality but utilizes a smaller 10-pin µMAX package.

Thermal Management Replacement Considerations

Public confirmed substitute part numbers: MAX6643LBAAEE+T, MAX6645ABFAUB.