TLE 5226 G

Semiconductor Group

Page

1998-02-04

8

Open load is detected for all four channels in on and off mode. In the on mode the load current is moni-

tored. If it drops below the specified threshold value, then an open load condition is detected.

In the off mode, the ouput voltage is monitored.

An open load condition is detected when the output voltage of a given channel is below 55 % of the

condition with a fixed offset of typ. 1.25 V to recognize GND bypasses. To suppress fault diagnosis

during the flyback phase of the compared output, the diagnostic circuit includes a latch function.

Reset of this latch is done at end of the flyback phase, additionally it can be reseted by a low signal on

the enable input or a high signal of the input line.

See block diagramm of open load detection on page 3.

Diagnostic Table

In general the status follows the input signal in normal operating conditions.

If any error is detected the status is inverted.

Operating Condition

Standby

Input

Enable

Input

Control

Input

Power

Output

Status

Output

STBY

ENA

IN

OUT

ST

Standby

L

X

X

OFF

H

Normal function

H

H

H

H

L

L

H

H

L

H

L

H

OFF

OFF

OFF

ON

L

L

L

H

Open load or short to ground

H

H

H

H

L

L

H

H

L

H

L

H

OFF

OFF

OFF

ON

H

H

H

L

Overload or short to supply

latched overload

reset latch

H

H

H

H

H

H

L

X

H

H

H

H

→ L

OFF

OFF

OFF

OFF

L

L

H

L

Overtemperature

latched overtemperature

reset latch

H

H

H

H

H

H

L

X

H

H

H

H

→ L

OFF

OFF

OFF

OFF

L

L

H

L