FDA903U datasheet(35/80 Pages) STMICROELECTRONICS

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DS12498 Rev 2

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FDA903U

Diagnostic

The FDA amplifiers family provides diagnostic function for detecting several possible faults

conditions.

Any warning information will be stored in the I2C interface and kept until the first I2C bus

reading operation. Some fault events can be sent to CDDiag pin as trigger for an interrupt

process.

Here reported the faults detectable taking advantage of FDA903U's diagnostic features:



Short to VCC/GND;



Short or open load (with DC diagnostic);



Open load during play;



Under/over voltage events;



Chip over temperature;



Digital input offset;



Output voltage offset;



Output current offset;



Output clipping;



Over current.

The fault events are managed with different actions depending on their severity.

It is important, for a correct diagnostic result collection, to clean diagnosis related I2C

10.1

DC diagnostic

The DC diagnostic is a routine performed to detect the load connection status.

FDA amplifiers family provides a highly reliable and noise immune load diagnostic

algorithm, in order to prevent false detections induced by supply voltage variations or

mechanical stress on the speaker (e.g. car door closing). The algorithm includes the internal

generation of a properly calibrated and pop-free test signal.

For an extensive description of the DC diagnostic feature, please refer to the DC Diagnostic

user manual.

10.1.1

Diagnostic control

DC diagnostic can be run setting via I2C "Start Diag DC".

Diagnostic signal is generated and test is performed only when all the following conditions

are true:

Channel is in MUTE state.

DC test enable bit is set from '0' to '1'.

The channel has power stage ON

Device is NOT kept in mute by means of the dedicated hardware pin

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