DocID027887 Rev 2

19/29

STPA008

General information

28

4.3

Protections

4.3.1

Short circuits and open load operation

When the IC detects a short circuit to ground, to Vbatt or across the load, the output of the

amplifier is put in three-state (high impedance condition).

In case of short circuit to ground or Vcc, the amplifier exits from the three-state condition

only when the short-circuit is released and the output returns inside the limits imposed by an

internal voltage comparator.

When a short across the load is present, the power stage sees an over-current and is

brought in protection mode for about 100 μs. After this time, if the short circuit condition is

removed the amplifier returns to play, otherwise the high impedance state is maintained and

the check is repeated every 100 μs.

Disconnection of load (open load condition) doesn't affect the amplifier, which continues to

play.

4.3.2

Over-voltage and load dump protection

When the battery voltage is higher than 19 V, the amplifier put in tri-state. It stops playing till

the supply voltage returns in the permitted range.

The amplifier is protected against load dump surges having amplitude as high as 50 V and a

rising time as low as 2 ms (see Figure 24).

Figure 24. Load dump protection diagram

4.3.3

Thermal protection

reduce output power and limit power dissipation. If this is not enough and the junction

temperature continues to increase, the amplifier is switched off when it reaches the

maximum temperature of 170 °C.

Figure 25. Thermal protection diagram