Figure 4 shows a typical application diagram for

DC motor driving. To assure the safety of the cir-

cuit in the reverse battery condition a reverse pro-

pend on the driving load.

ited to the

allows open load detection. To protect the device

at the outputs against EMI or ESD > 2KV external

CIRCUIT DESCRIPTION

L9925 is a dual full bridge IC designed to drive

DC motors, stepper motors and other inductive

loads. Eah bridge has 4 power DMOS transistor

Ω and the relative protection

and control circuitry (see fig. 5). Tthe 4 half

bridges can be controlled independently by

means of the 4 inputs IN1, IN3, IN4 and 2 enable

inputs ENABLE1 and ENABLE2.

LOGIC DRIVE (true table for the two full bridges)

INPUTS

OUTPUT

MOSFETS

IN1

IN3

IN2

IN4

EN1 = EN2 = H

L

L

H

H

L

H

L

H

Sink 1, Sink2

Sink1, Source2

Source1, Sink2

Source1, Source2

@Tj > 150

°C

X

X

All transistors turned OFF

EN1 = EN2 = L

X

X

All transistors turned OFF

L = Low; H = High; X = Don’t care

CROSS CONDUCTION

The device guarantees the absence of cross-con-

duction by watching internal gate-source voltage

of the driving power DMOS.

TRANSISTOR OPERATION

ON STATE

When one of POWER DMOS transistors is ON it

Ω

at a junction temperature of 25

°C

CHARGE

PUMP

TEMP

OUT1

VS1

OUT2

IN2

PGND1

VS2

OUT3

OUT4

IN1

EN1

GND

EN2

O

O

O

I/O

I/O

I/O

40V

10K

Ω

10K

Ω

100nF

100

µF

+5V

O

O

IN3

IN4

2nd FULL BRIDGE

1st FULL BRIDGE

5V

REGULATOR

EN1

µP

EN1

EN1

EN2

40V

7V

7V

7V

T1

T1

T2

T2

T1 T2

CHARGE

PUMP

PGND2

D99AT423

100nF

100nF

100nF

100nF

A

B

STEPPER MOTOR

Figure 4. Application Diagram

L9925

5/9