1

Features

s

Buffered Speed Sensor

Output

s

No Cross-conduction in

either H-bridge

s

Guaranteed Monotonic

s

On Chip Flyback Diodes

s

Fault Protection

Overvoltage

Short Circuit Protection

Load Dump Protection

to 60V

Package Options

8 Lead PDIP

Stepper Motor Driver

with Buffered Speed Signal Output

1

Gnd

COILA+

COILA–

SENSOR

IN

COILB+

COILB–

SENSOR

OUT

Description

Block Diagram

Absolute Maximum Ratings

CS8442

December, 2001 - Rev. 2

ON Semiconductor

2000 South County Trail, East Greenwich, RI 02818

Tel: (401)885–3600 Fax: (401)885–5786

N. American Technical Support: 800-282-9855

Web Site: www.cherry–semi.com

The CS8442 is a stepper motor

driver that implements an H-

bridge design to drive two coils in

an eight step sequence each revo-

lution. Each H-bridge is capable of

delivering 85mA to the load.

The sequencer function insures

that the odometer is monotonic

and that cross-conduction of each

H bridges does not occur. Before

the beginning of each sequence,

both bridges are turned off. This

“dead zone” minimizes the fly

back energy generated in the

inductive loads. In addition, on

board clamp diodes across each

output protect the output drive

transistors from excessive fly back

voltages.

The CS8442 is fault protected

against reverse battery, short cir-

cuit, and over voltage conditions.

If a fault is detected, the IC shuts

down.

The buffered speed signal output

(SENSOR OUT) is an open collec-

tor NPN capable of driving a

4.7k

Ω load connected to a 5V sup-

ply. The signal is a buffered,

inverted version of the speed sen-

sor input voltage (SENSOR IN).

The input voltage can be either a

sine or square wave form.

(100ms pulse transient) -40˚C to +105˚C ......................–0.5 to 60V

Junction Temperature.............................................................–40°C to +150°C

Speed Sensor Output .....................................................................................7V

ESD (Human Body Model) .........................................................................2kV

Lead Temperature Soldering

Wave Solder (through hole styles only) ........10 sec. max, 260°C peak

COILB-

SENSOR

IN

SENSOR

OUT

Coil

Driver

B

Coil

Driver

A

Overvoltage

and Short

Circuit

Protection

Sequencer

COILA-

COILA+

Input

Comp.