D a tash eet T L E 6228 G P

V3.1

Page

26. Aug. 2002

7

Application Description

This IC is especially designed to drive inductive loads (relays, electromagnetic valves).

Integrated clamp-diodes limit the output voltage when inductive loads are discharged.

Four open-drain logic outputs indicate the status of the integrated ciruit. The following conditions are

monitored and signalled:

- overloading of output (also shorted load to supply) in active mode

- open and shorted load to ground in active and inactive mode

- overtemperature

Circuit Description

Input Circuits

The control and enable inputs, both active high, consist of schmitt triggers with hysteresis. All inputs

are provided with pull-down current sources. Not connected inputs are interpreted as low and the re-

spective output stages are switched off.

In standby mode (STBY = LOW ) the current consumption is greatly reduced.

The circuit is active when STBY = HIGH.

If the standby function is not used, it is allowed to connect the standby pin directly to VS.

Status Signals: The status signals are undefined for 2ms after a power up event or a STBY low to high

transition.

Output Stages

The four power outputs consist of DMOS-power transistors with open drains. The output stages are

short circuit protected throughout the operating range. Each output has it's own zenerclamp. This

causes a voltage limitation at the power transistor when inductive loads are switched off.

Parallel to the DMOS transistors there are internal pull down current sources. They are provided to

detect an open load condition in the off state. They will be disconnected in the standby mode.

Due to EMI measures there is an internal zenerclamp in parallel to the output stage. It gets active

Protective Circuits

The outputs are protected

signal at the input is switched off and on again.

Fault Detection

The status outputs indicate the switching state of the output stage. Under normal conditions is: ST =

low

Output off; ST = high

Output on. If an error occurs, the logic level of the status output is in-

verted, as listed in the diagnostic table.

normal operation or permanently.