FDA903D datasheet(38/82 Pages) STMICROELECTRONICS

Part #	FDA903D

Description	1 x 45 W class D digital input automotive power amplifier with ILoad current monitoring, wide voltage operation range for car audio and telematic

PDF	82 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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38 / 82 page

Diagnostic

FDA903D

38/82

DocID031502 Rev 2

11.2

Short to Vcc / GND diagnostic

The short to Vcc/GND diagnostic performs the detection of:



"Hard" and "soft" short to Vcc



"Hard" and "soft" short to Gnd

Timing

Short to Vcc/Gnd diagnostic cycle duration is 90 ms(*).

If a short to Vcc/Gnd is not stable during diagnostic cycle the channel will remain in "Diag.

Vcc/Gnd" state until a fault or non-fault condition is stable for at least 90 ms(*).

This special function avoids wrong detections in case of disturbs caused by mechanical

stresses applied to the speaker (e.g. car door closing).

The short to Vcc/Gnd diagnostic starts automatically following the logic shown in Figure 38.

Results communication and I2C control

After performing Short to Vcc/Gnd diagnostic for 90 ms(*) with a stable fault/non-fault

condition, there are two different scenarios:

Fault present: the device is communicating the fault condition setting the I2C bit DB2[3]

(in case of short to Vcc) or DB2[2] (in case of short to Gnd). The amplifier is remaining

in "Diag. Vcc/Gnd" state until the short is removed

Fault not present: Short to Vcc/Gnd diagnostic ends and the state machine can evolve

following the I2C commands.

Note:

(*) Time when default I2C parameters settings are used

11.3

Diagnostic time-line diagrams

Figure 47. DC diagnostic before turn on

FDA903D Datasheet(PDF) 38 Page - STMicroelectronics