MAX6643LBFAEE+T

Thermal Management Overview

The MAX6643LBFAEE+T is an automatic PWM fan-speed controller with overtemperature output, manufactured by Analog Devices Inc./Maxim Integrated. It operates within a supply voltage range of +3.0V to +5.5V and consumes a typical operating current of 500µA. The device monitors two temperature locations, including its own die temperature and an optional external transistor's temperature. It generates a 32Hz PWM waveform to drive an external power transistor for fan speed modulation. The unit features pin-selectable high and low-temperature thresholds in 5°C increments, a FULLSPD input for 100% duty cycle control, and a FANFAIL output for detecting fan failures via tachometer or locked-rotor signals. It is housed in a 16-pin QSOP package.

Thermal Management Feature Summary

• Monitors internal die temperature and one external diode-connected transistor for precise thermal management
• Generates a 32Hz PWM output with controlled duty-cycle rate-of-change to minimize acoustic noise
• Detects fan failure through locked-rotor logic, tachometer pulses, or fan-supply current sensing
• Includes a FULLSPD input that forces the PWM duty cycle to 100% when activated

Thermal Management Applications

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

Thermal Management Procurement Notes

Verify the specific suffix 'E' corresponds to the 16-pin QSOP package and the 'T' indicates tape-and-reel packaging as per the manufacturer's ordering guide. Confirm that the LB designation aligns with the required pin-selectable threshold configurations. Ensure compatibility with the intended system's voltage levels and thermal requirements before finalizing procurement.

Thermal Management Selection Notes

Select this component when simultaneous monitoring of local and remote temperatures is required for single-fan applications. The pin-selectable thresholds offer flexibility without requiring microcontroller intervention for basic thermal control. Consider the 16-pin QSOP footprint during PCB layout planning. Verify that the external power transistor can handle the load driven by the PWM_OUT signal.

Thermal Management Part Context

This part belongs to the MAX6643/MAX6644/MAX6645 family of automatic PWM fan-speed controllers. While the MAX6644 supports dual fans and external sensors only, and the MAX6645 uses a smaller µMAX package, the MAX6643 specifically integrates local die temperature sensing alongside one remote sensor channel in a 16-pin QSOP form factor.

Thermal Management Replacement Considerations

Direct substitutes include MAX6643LBBAEE+T (identical function/package) and MAX6644LBAAEE+T (dual-fan capability). Cross-family replacements like MAX6663 require verification of interface and pinout compatibility.