TDA7572 Datasheet, PDF (54/64 Pages) STMicroelectronics – 200W mono bridge PWM amplifier with built-in step-up converter

Under voltage lock out (UVLO)
12 Under voltage lock out (UVLO)
TDA7572
The UVLO lock at the voltage references value used to run the device. If some of them are
not in the rate band the system is put in tristate or in stand-by. The Auto-mute Voltage
Setting pin (pin56) voltage is used to define the limits of this voltage references.
List of monitored pin:
1. MODE0 and MODE1 voltage value
2. VSP-VSM voltage difference
3. SVR voltage value
4. VSP-SVR or VSR-VSM voltage difference
5. V14 voltage value
In the UVLO could be defined four blocks:
– VSP - UVLO
– VP2.5/VM2.5 UVLO
– V14 - UVLO
– SVR - UVLO
12.1
VSP-UVLO
This block monitors the VSP-VSM drop and eventually moves the modulator in mute or in
tristate. The limits imposed by the VSP-UVLO block are principally three:
1. an adjustable limit on the minimum supply/drop
2. an adjustable limit on the maximum supply/drop
3. an absolute limit on the maximum supply
The adjustable limits are obtained by means of the reference voltage present on the
AutomuteVSetting pin, which is fixed by means of a ladder resistor of R1 and R2 between
VP2.5 and SVR.
The comparators that sense the voltage drop for the auto mute are provided of hysteresis.
An hysteresis is still present for the auto-tristate and expressed in the spec as two different
thresholds that are function of reference voltage and slope polarity.
12.2
V14 - UVLO
This block monitors the V14-VSM drop voltage and eventually moves the modulator in mute
or in tristate. The V14-UVLO block fixes a limit on the minimum drop.
An hysteresis is present for the auto-tristate and expressed in the spec as two different
thresholds that are function of slope polarity. An hysteresis is still present for the auto-mute
and expressed in the spec as two different thresholds that are function of auto-tristate
threshold and slope polarity.
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