L9969T datasheet(34/70 Pages) STMICROELECTRONICS

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Table 21. Short circuit detection parameters

Symbol

Parameter

Condition

Min Typ Max Unit

I_ouk_2 Overcurrent detection at CL = 2

Short Circuit to Ground or

Battery or Across Load

4.9

8.2

I_ouk_3 Overcurrent detection at CL = 3 (default)

Short Circuit to Ground or

Battery or Across Load

6.7

11.1

I_ouk_4 Overcurrent detection at CL = 4

Short Circuit to Ground or

Battery or Across Load

8.4

0.3

t DF_H Delay time for fault detection

0.5 Ω at 25 μH

µs

t DF_off Time from detected fault to high impedance of outputs

0.5 Ω at 25 μH

µs

tDF_del

Free-wheeling time. Time for the delayed switch off

between the switch off of both outputs after a detected

short circuit at one output

200

µs

t SC

Timeout during reconfirmation sequence

290 350 413

µs

tretest

Duration of the switch on/switch off sequence of OUTx after

a detected short circuit at one output

290 350 413

µs

Each error has to be confirmed before being stored in the DIA_REG1.

3.2.6.6

Short circuit across load

In case of a short circuit across load, it is possible that two failures are detected at the same time (but not

necessarily): a short to ground on one side and a short to battery on the other side. The HBR has to run a

sequence internally, if there is only a single short circuit to ground on the high-side switch or a single short circuit

to VS on the low side switch or if there is really a short circuit across the load. This sequence is executed every

time a single short cut is detected, to prevent a false error reporting. The SCL algorithm should look as follows

(see Figure 21).

Figure 21. Principle of the short circuit across load detection

When an error was detected at any output pin the output stages are turned off immediately.

Below, some examples of how the SCL detection procedure works.

L9969x

Functional description

DS14029 - Rev 6

page 34/70

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