TDA7572 Datasheet, PDF (56/64 Pages) STMicroelectronics – 200W mono bridge PWM amplifier with built-in step-up converter

Start-up procedures, modulator turn-on after a tristate condition.
TDA7572
13 Start-up procedures, modulator turn-on after a
tristate condition.
13.1
Start-up
Condition to be respected to turn-on the modulator at the start-up:
● Are MODE0 and/or MODE1 pins at voltage higher than 2.3V?
● Is the command “TristateMOD” Set to “1”?
● Is the PLL locked? (Only in case of digital Input)
● Is the Thermal protection FLAG ON?
● Are the VSP-VP2.5 and VM2.5-VSM drop voltage respectively over VAP and VAM?
● Is the VSP-VSM voltage lower than V_U and V_UC?
● Is the total VSP-VSM Higher than VPO+?
● Is the SVR pin higher than Vsvr+?
● Is the 14V pin supply higher than V14mute+?
TristateMOD represents an internal signal which is
– in NOI²CBUS MODE set to '1' when the digital supply pin VDIG (50) reaches its
steady state value.
– in I²C MODE set to '1' when the digital supply pin VDIG (50) reaches its steady
state value and by I²C bus is written '1' on the D4 bit of modulator register.
– in NOI²CDIAGNOSTIC set to '1' when the digital supply pin VDIG (50) reaches its
steady state value and the turn-on diagnostic has positive result.
The thermal protection represent an internal signal which is set to '1' at the start-up and
eventually set to '0' if
– the internal temperature trespass the second threshold and/or
– the external temperature trespass the second threshold
Once all the listed condition present in the above table are respected the modulator is get
out from tri-state after ~500µs.
13.2
Tristate
When the modulator is put in tristate by some diagnostic condition the system retrieve from
this condition in two possible mode depending from the supplies configuration
– split supply: The modulator starts to switch ~500µs after all conditions listed in the
above table are realized.
– Single-supply: Only in case of single supply, is activated a circuit that inhibit the
startup of the SVR capacitor charge (then the modulator enable) if the SVR
voltage is higher than 1.5V. If, during the normal activity of the modulator, an event
that moves the modulator in tristate is present (due to, as example, an UVLO) the
Vsvr gets to discharge until its value is under 1.5V. Ones reached this value the
capacitor svr start to charge. The modulator starts to switch ~500µs after all
conditions listed in the above table are realized. Purpose of this circuit is to avoid
fast turn-off/on of the modulator and increase the pop performance.
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