FUNCTIONAL DESCRIPTION

Function

Description

GENERAL

The TDA7372B is a quad channel single package audio power amplifier intended to reduce the

mismatch in the electrical characteristics among the four different channels and to consistently

drop the external component count. It contains four non inverting stages whose gain is

internally fixed to 40dB.

OUTPUT STAGE

The output stage is a single ended type suitable to drine 4

Ω loads. It consists of a class AB fully

complementary PNP/NPN stages short circuit protected.

A rail to rail output swing is achieved without need of boostrap capacitors. Moreover, the

external compensation is not necessary.

ST-BY

The device features a St-BY function which shuts down the internal bias supplies when the ST-

BY input is low. In ST-BY mode the amplifier sinks a small current (in the range of few

µAs).

When the St-BY pin is high the IC becomes fully operational.

MUTE

A mute function is also provided. This reduces the gain of the input stage to a level effectively

eliminating any audio input influence on the output stage when the mute line is low. When the

mute line is high the normal input path is restored.

The device goes automatically is mute status when the supply voltage goes below the minimum

allowed value. This prevents pop noises whenever the battery voltage drops below a fixed

threshold. When the supply voltage rises to its nominal value the device recovers the play

THERMAL

PROTECTION

The Thermal protection principle involves two different steps

a) Soft thermal limitation

b) Shutdown

Until the juntion temperature remains below a preset threshold, the I.C. will deliver the full

power. Once the threshold has been reached, the device automatically goes, into mute status.

The play to mute transition is internally controlled so producing a soft muting without unpleasent

effect. Supposing the junction temperature does not reduce to safe levels a complete shutdown

will occur.

BUILT-IN SHORT

CIRCUIT

PROTECTION

Reliable and safe operation in presence of:

- AC short circuit to GND

is assured by a built-in protection circuitry.

the DC short protector acts in such a way to avoid the device is turned on (by ST-BY) when a

More over, as the involved circuitry is normally disabled when a current higher than 5mA is

flowing into the st-by pin, it is important, in order not to disable it, to have the external current

source driving the pin it self limited to 5mA. (figure 1 is showing relevant waveforms).

Figure 15: Fault (DC short) waveforms

TDA7372B

8/10