General Description

The US90A/91A is a one-chip solution for driving two-coil brushless DC cooling fans.

Based  on  the  advanced  Melexis  CMOS  process, the  IC  contains  a  Hall-effect  sensor,  dynamic offset correction and low side output drivers.

Features and Benefits

 Low cost

 High sensitivity Hall Sensor

 Locked rotor protection and auto-restart

 Power-efficient CMOS and power MOSFETs

 Built-in output protection clamping diode

 Integrated tachometer (US90A) or alarm (US91A) signal output

 2-coil fan driver with FG/RD output in 4-pin VK / VA and 8-pin narrow SOIC packages (all RoHS Compliant)

Application Examples

 12V/24V fans

 Peak current up to 500mA