February 1999

Figure 1. Block diagram.

PBL 3770A

High Performance

Stepper Motor Drive Circuit

16-pin plastic batwing DIP

28-pin plastic PLCC package

20-pin SO

Description

PBL 3770A is a bipolar monolithic circuit intended to control and drive the current in

one winding of a stepper motor. It is a high power version of PBL 3717 and special

care has been taken to optimize the power handling capability without suffering in

reliability.

The circuit consists of a LS-TTL compatible logic input stage, a current sensor, a

monostable multivibrator and a high power H-bridge output stage. The circuit is

pin-compatible with the PBL 3717 industry-standard driver.

Two PBL 3770A and a small number of external components form a complete

control and drive unit for LS-TTL or microprocessor-controlled stepper motor

systems.

Key Features

•

Half-step and full-step operation.

•

Switched mode bipolar constant

current drive

•

Wide range of current control

5 -1800 mA.

•

Wide voltage range 10 - 45 V.

•

Designed for unstabilized motor

supply voltage.

•

Current levels can be selected in

steps or varied continuously.

•

Thermal overload protection.

1

GND

V

CC

M

B

Phase

I

1

V

R

&

&

&

&

–

+

–

+

–

+

Monostable

t

= 0.69 • R • C

Current Sensor

Output Stage

off

T

T

Schmitt

Trigger

Time

Delay

C

T

E

PBL 3770A

1

≥1

≥1

≥1

≥1