TDA7572 datasheet(56/64 Pages) STMICROELECTRONICS

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Start-up procedures, modulator turn-on after a tristate condition.

TDA7572

56/64

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:

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.

●

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 VU and VUC?

●

Is the total VSP-VSM Higher than VPO+?

●

Is the SVR pin higher than Vsvr+?

●

Is the 14V pin supply higher than V14mute+?

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