TDF8554J NXP Semiconductors, TDF8554J Datasheet - Page 9

• Manufacturer Part Number: TDF8554J
• Description: The TDF8554J is one of a new generation of complementary quad Bridge-Tied Load(BTL) audio power amplifiers with full I²C-bus controlled diagnostics, multiple voltageregulator and two power switches intended for automotive applications
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TDF8554J
Product data sheet
Fig 3.
start enable
DB2 [D7]
amplifier
IB1 [D0]
output
DIAG
POR
SVR
STB
V
Start-up and shut-down in I
P
7.2 Engine start and low voltage operation
If the amplifier starts, and a speaker fault occurs (double-fault condition: one side of the
speaker connected to ground and one side of the speaker connected to one output), the
amplifier only sets the speaker fault detection bits.
If the amplifier is switched off by the I
the capacitor on pin SVR is discharged. 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 for instance, when an external engine start detection is used.
The voltage on pin SVR is used as a reference voltage for the input bias (set to
0.23  battery voltage + 2  diode voltage V
filtered supply voltage at the amplifier output. The capacitor on pin SVR is required for
improved supply voltage ripple rejection and channel separation between the four
channels.
The DC output voltage relates to the SVR voltage to prevent common mode ripple on the
speaker lines. If the supply voltage drops during an engine start, the output will follow
slowly due to the SVR capacitor. To create sufficient headroom for the output signal below
a battery voltage of 10 V, the DC-output voltage will directly follow half the supply voltage.
t
d(mute-off)
t
wake
t
amp-on
2
C mode
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 31 August 2011
4 45 W power amplifier with multiple voltage regulator
t
d(fast-mute)
2
C-bus (IB1[D0] = 0), the soft mute is activated and
be
) and as a reference for generating half the
TDF8554J
© NXP B.V. 2011. All rights reserved.
t
off
001aam685
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