General information

STPA002

18/24

DocID024368 Rev 3

5.3

Protections

5.3.1

Short circuits and open circuit operation

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

amplifier is put in three-state (high impedance condition). The power stage remains in this

condition until the short is removed.

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

only when 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 150 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 150 μs.

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

to play.

5.3.2

Over-voltage and load dump protection

When the battery voltage is higher than 19 V, the amplifier is switched to a high impedance

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 lower than 5 ms (see Figure 24).

Figure 24. Load dump protection diagram

5.3.3

Thermal protection

If the junction temperature of the IC reaches Tj = 150 °C, a smooth mute is applied to 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