US890 / US891
Two-Coil Fan Driver – High Output Current
Features and Benefits
Peak output current up to 1200mA
Low start-up voltage
Low output resistance
High sensitivity integrated Hall Sensor
Power-efficient CMOS and power MOSFETs
Built-in output protection clamping diode
Locked rotor protection and auto-restart
Integrated tachometer (US890) or alarm (US891)
signal protected output
Low cost
2-coil fan driver with FG/RD output in
RoHS Compliant 4-pin VK package
Application Examples
5V/12V DC brushless motor/fan
PC, server, laptop cooling fan
Power supply cooling fan
Large and small fan size
Ordering Information
Part No.
US890
US891
Temperature Code
E (-40° to 85°
C
C)
E (-40° to 85°
C
C)
Package Code
VK (4-pin TO-92)
VK (4-pin TO-92)
1 Functional Diagram
2 General Description
The US890/891 is a one-chip solution for driving
two-coil brushless DC motors and fans.
Based on the advanced Melexis CMOS process,
the IC contains a Hall-effect sensor, dynamic
offset correction and powerful output drivers with
1200mA peak output current capability.
Specially designed for driving large fans, the
device is optimized for low start-up voltage.
Frequency Generator or Rotation Detection is
available. The open-drain output makes easier the
connectivity with any external interface such as
hardware monitoring or Super I/O IC.
These features are combined with the Melexis
patented no-V
DD
design to fit the IC in a small 4-
pin VK package.
3901000890
Rev 002
Page 1 of 12
Data Sheet
Sep/07
MELEXIS [ Melexis Microelectronic Systems ]
