MAX6645ABFAUB+T

Thermal Management Overview

The MAX6645ABFAUB+T is an automatic PWM fan-speed controller with overtemperature output. It operates from a 3.0V to 5.5V supply and consumes 500µA typical current. The device measures temperatures of one or two external diode-connected transistors and adjusts the PWM duty cycle to control fan speed based on cooling needs. It features a 32Hz PWM output, a locked-rotor detection capability via FANFAIL, and an active-low OT alarm. Factory-programmed thresholds replace pin-selectable options found in other variants.

Thermal Management Feature Summary

• Automatically adjusts fan speed by monitoring external temperature sensors and modulating PWM duty cycle
• Detects fan failure through locked-rotor logic, tachometer signals, or fan-supply current sensing
• Provides an active-low overtemperature alarm output for system warnings or shutdown

Thermal Management Applications

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

Thermal Management Procurement Notes

Verify the specific suffix 'UB' indicates the 10-pin µMAX package configuration. Confirm that the factory-programmed threshold settings match the required thermal trip points, as they cannot be adjusted via hardware pins like the MAX6643 or MAX6644. Ensure the remote diode characteristics align with the device's optimized ideality factor for accurate readings.

Thermal Management Selection Notes

Select this part when fixed thermal thresholds are acceptable, eliminating the need for pin-strapping configurations. It is suitable for applications requiring dual-channel remote temperature sensing and comprehensive fan-failure diagnostics. Verify that the 10-pin µMAX package fits the board layout constraints compared to the larger QSOP packages used by similar family members.

Thermal Management Part Context

This component belongs to the MAX6643/MAX6644/MAX6645 family of automatic PWM fan-speed controllers. Unlike the MAX6643 and MAX6644, which offer pin-selectable high and low temperature thresholds, the MAX6645 has these values factory programmed. It shares the same core functionality of temperature monitoring and fan control but utilizes a smaller 10-pin µMAX package instead of the 16-pin QSOP.

Thermal Management Replacement Considerations

Direct replacements include MAX6643LBFAEE+T and MAX6644LBAAEE+T, provided the application can accommodate pin-selectable threshold configurations and the larger 16-pin QSOP package.