TLE 5207

Semiconductor Group

3

1998-02-01

Circuit Description

Input Circuit

The control inputs consist of TTL/CMOS-compatible Schmitt triggers with hysteresis.

Buffer amplifiers are driven by these stages and convert the logic signal into the

necessary form for driving the power output stages.In case of low potential at both inputs

the device is switched in inhibit-condition with very low current consumption.

Output Stages

The output stages from a switched H-bridge. Protective circuits make the outputs short-

circuit proof from ground up to a supply voltage of 16 V. Positive and negative voltage

spikes, which occur when switching inductive loads, are limited by integrated power

diodes.

Monitoring and Protective Functions

An internal circuit ensures that all output transistors are turned-OFF if the supply voltage

is below the operating range.

A monitoring circuit for each output transistor detects whether the particular transistor is

active and in this case prevents the corresponding source transistor (sink transistor) from

conducting in sink operation (source operation). This effectively guards against

crossover currents. Pulse-width operation is possible up to a maximum switching

frequency of 1 kHz for any load.

Depending on the load current higher frequencies are possible.

Functional Truth Table

I1

I2

Q1

Q2

Comments

L

L

Z

Z

Device in inhibit condition with very low current

consumption; outputs in tristate condition (high impedance)

L

H

L

H

Motor turns clockwise

H

L

H

L

Motor turns counterclockwise

H

H

H

H

Motor brake; both high side transistors turned-ON

Notes for Output Stage

Symbol

Value

L

Low side transistor is turned-ON; High side transistor is turned-OFF

H

High side transistor is turned-ON; Low side transistor is turned-OFF

Z

High side transistor and Low side transistor are turned-OFF