TDF8544
NXP Semiconductors
I2C-bus controlled 4 50 W power amplifier
During start-up, the ampifier cannot distinguish between a short to ground or a speaker
fault. If there is a speaker fault during start-up, the amplifer enters protection mode and
switches off that channel.
If the amplifier starts and a speaker fault occurs (double-fault condition, one side of the
speaker connected to ground and one side connected to one output), the amplifier only
sets the speaker fault detection bits.
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.
V
P
DIAG
DB2[D7]
POR
IB1[D0]
start enable
t
wake
STB
SVR
t
amp-on
amplifier
output
t
off
t
t
d(mute-off)
d(fast-mute)
001aam685
Fig 4. Start-up and shut-down in I2C-bus mode
TDF8544
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© NXP B.V. 2011. All rights reserved.
Product data sheet
Rev. 2 — 29 August 2011
8 of 54
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