TDF8541JSSLASHN2 datasheet(8/54 Pages) NXP

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TDF8541

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Product data sheet

Rev. 3 — 13 December 2011

8 of 54

NXP Semiconductors

TDF8541

I2C-bus controlled 4

 45 W power amplifier

During start-up, the amplifier cannot distinguish between a short to ground or a speaker

fault. If there is a speaker fault during start-up, the amplifier enters protection mode and

switches off that channel.

If the amplifier starts and a speaker fault occurs, the amplifier only sets the speaker fault

detection bits. A speaker fault is a double-fault condition where one side of the speaker is

connected to ground or supply and the other side of the speaker is connected to an

output. The other output of the channel is left open.

If the amplifier is switched off by I2C-bus (IB1[D0] = 0) the soft mute is activated and the

capacitor on pin SVR is discharged. If the amplifier is switched off in legacy mode,

pin STB must be set to mute for 50 ms to ensure a low switch-off plop and then pin STB

can be set to ground which discharges the SVR capacitor.

If the amplifier is switched off by pulling pin STB LOW, the amplifier is muted (fast mute)

and then the capacitor on pin SVR is discharged. This fast mute can be used in I2C-bus

and legacy mode, when for instance an external engine start detection is used.

Fig 4.

Start-up and shut-down in I2C-bus mode

twake

td(fast-mute)

td(mute-off)

toff

tamp-on

DIAG

STB

SVR

amplifier

output

DB2[D7]

POR

IB1[D0]

start enable

001aam685

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