US890 / US891

Two-Coil Fan Driver – High Output Current

3901000890

Page 3 of 12

Data Sheet

Rev 002

Sep/07

3 Glossary of Terms

Two-coil fan

A fan with two-coil windings where current alternates from 1 coil to the other

depending on the direction of the magnetic field.

MilliTesla (mT), Gauss

Units of magnetic flux density :

1mT = 10 Gauss

Voltage on the common point of the fan coils.

Current supplying the chip which flows through the coil connected to the

switched off output driver.

Peak output current

The current flowing in the coil at start-up, only limited by the coil resistance

Continuous output current

The average current flowing in the coil when the fan is spinning normally.

Locked rotor

The state when the fan stopped spinning due to mechanical blockage.

FG

Frequency generator or tachometer output

RD

Rotation detection or alarm output

4 Absolute Maximum Ratings

Parameter

Symbol

Value

Units

Fan Supply Voltage

18

V

Peak Output Current

1200

mA

Continuous Output Current

600

mA

FG/RD Pull-Up Voltage

18

V

FG/RD Reverse Current

60

mA

Operating Temperature Range

-40 to 85

°C

Junction Temperature

125

°C

Storage Temperature Range

-55 to 150

°C

Magnetic Flux Density

B

Unlimited

mT

ESD Sensitivity (AEC Q100 002)

-

4

kV

Table 1: Absolute maximum ratings

Exceeding the absolute maximum ratings may cause permanent damage. Exposure to absolute-maximum-

rated conditions for extended periods may affect device reliability.

5 Pin Definitions and Descriptions

Pin Name

Pin number

Function

FG (RD)

1

Frequency Generator (Rotation Detection) Open Drain Output

OUT1

2

Open Drain Coil Driver 1

OUT2

3

Open Drain Coil Driver 2

GND

4

Ground pin

Table 2: Pin definitions and descriptions