TDA7572 datasheet(48/64 Pages) STMICROELECTRONICS

48 / 64 page

Diagnostics

TDA7572

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Diagnostics

Diagnostics are grouped into two categories, those performed only during standby, and

those available during amplifier operation.

When Mode[1:0] indicate the I2C is active, the RunDiag bit must be set (by an I2C write to

the Faults1 register) to initiate diagnostics.

When Mode[1:0]indicate the I2C is not active, the state of Mode[1:0] are further decoded to

determine if the diagnostics should be run automatically during power-up

Diagnostics performed during power-up (Power Up Diagnostic or PUD, sometimes called

"Turn-on-diagnostics") are:

Output shorted to ground

Output shorted to Vs

Shorted transducer

Open Transducer

During operation the following conditions are continuously monitored:

DC offset across the speaker

Die temperature

External temperature

Output Clipping

Output overcurrent

Power supply overcurrent

Faults are reported in a simple manner for bus free operation. The open drain WS/Clip_L pin

asserts when clipping occurs, and the Address0/Fault_L pin asserts if any there are any

other faults. In case of busfree operation the Address0/Fault is the logical OR of all fault

conditions. When I2C bus is present, one can read detailed fault status, as well as control

the diagnostics being performed via TDA7572's registers, Address0/Fault_L is used to

determine which one has to be the I2C bus Address0 of this IC or, in case of DAC operation,

it is used to assert when clipping occurs. In this case the Address0 of I2C bus address is

automatically set to zero, which implies that only two TDA7572 can be addressed. In any

Mode case a clipping output is present.

The detailed procedure implemented to manage these faults follows:

10.1

Faults during operation:

10.1.1

DC offset across the speaker

I2Cbus: If the module of VHOUTF1 - VHOUTF2 > 3Vfor more then 100ms the Offset bit in

W1TC procedure. Resetting the bit removes the tristate mode and modulator operation is

restored

No I2Cbus: Operation is as above except the fault is also reported by asserting the

Address0/Fault_L pin. In order to restart the system is necessary to pass through standby

mode.

TDA7572 Datasheet(PDF) 48 Page - STMicroelectronics

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