TDA7572 datasheet(43/64 Pages) STMICROELECTRONICS

43 / 64 page

TDA7572

Modulator

43/64

consists in a clipping of current when the first threshold for VDS is trespassed. It is obtained

by sink or source current to the virtual ground of modulator integrator. The cycle-by-cycle

limitation is a strong limitation. If the second VDS threshold is trespassed for more than

about 2µs the half bridge is tri-stated. If this condition persists for more then four PWM

periods the modulator is definitely tri-stated. It is possible setting the threshold VDS voltage

for the current limiting by the pin IlimitThreshold: the first threshold is the value voltage value

of this pin (referred to VN2.5), the second one is the same value multiply by the factor 1.5.

7.2

ANTI-POP shunt driver

The device is provided by a driver able to control an anti-pop shunt MOS which is

connectable in series or in parallel to the load. During the mute-to-play or play-to-mute

transition an external MOS is able to disconnect (MOS in series) or short (MOS in parallel)

the speaker in order to reduce the audible pop noise.

The shunt driver is able to source or sink a predefined current (see Table 17). The following

diagram reports the temporal behave of current at the shunt pin respect to the voltage on the

mute pin in NOI2CBUS mode.

Figure 6.

Current sourced by the shunt pin in NO I2Cbus mode

In I2Cbus mode it is possible to change the driver current direction only by change the bit D0

of byte 5. When the bit is set to 1 the current is sourced. By default the current is sourced.

Isource

Vsd+Vsdh

Vmute

AC00018

TDA7572 Datasheet(PDF) 43 Page - STMicroelectronics