TDA8596_15 Datasheet, PDF (12/48 Pages) NXP Semiconductors – I2C-bus controlled 4 ´ 45 W power amplifier with symmetrical inputs

NXP Semiconductors
TDA8596
I²C-bus controlled 4 × 45 W power amplifier with symmetrical inputs
V_P
DIAG
on
STB mute
standby
SVR
amplifier
output
t_{amp_on}
soft
mute
t_off
fast
mute
t_{d(mute_off)}
t_{d(soft_mute)} t_{d(mute_on)}
Fig 6. Start-up and shut-down timing in legacy mode
t_{d(fast_mute)}
001aad 171
7.7 Power-on reset and supply voltage spikes
If the supply voltage drops below 5 V in I²C-bus mode (see Figure 8 and 9), the content of
the I²C-bus latches cannot be guaranteed and a power-on reset will be performed. This
will cause all latches to be reset, the amplifier to be switched off and the DIAG pin to be
pulled LOW, indicating that a power-on reset has occurred (see DB2[D7]). When bit
IB1[D0] is set, the power-on flag is reset, the DIAG pin is released and the amplifier will
start-up.
In legacy mode a supply voltage drop below 5 V will switch off the amplifier without pulling
the DIAG pin LOW.
7.8 Engine start and low voltage operation
In steady state, the DC output voltage of an amplifier channel V_O equals half the supply
voltage (HVP). This voltage is related to the voltage on the SVR pin (refer to Figure 7:
V_O = V_SVR − 1.4 V). An external capacitor has been connected to the SVR pin to suppress
coupling of power supply ripple to the amplifier outputs.
The headroom voltage V_hr is defined as the difference between the supply voltage V_P and
the DC output voltage V_O, i.e. V_hr = V_P − V_O (refer to Figure 7). If the supply voltage drops,
e.g. during an engine start, the outputs will follow slowly due to the capacitor on pin SVR.
However, if the headroom voltage V_hr drops below the headroom protection threshold of
1.6 V, the headroom protection will be activated to prevent pop noise at the output. This
protection will first activate the fast mute and will subsequently discharge the capacitor on
pin SVR to generate more headroom for the amplifier (refer to Figure 8 and 9).
TDA8596_2
Product data sheet
Rev. 02 — 8 November 2007
© NXP B.V. 2007. All rights reserved.
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