TDF8554J NXP Semiconductors, TDF8554J Datasheet - Page 14

• 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
7.5.1 Start-up diagnostics with DC load detection
Table 4.
If the start-up diagnostics are enabled, the load condition of all four channels is
determined. At the end of the start-up diagnostics cycle, not only the load condition is
known (shorted load, normal load or open load), but also if a separate amplifier is
connected or if the outputs are shorted to battery or ground. If a separate amplifier
(booster) is detected, the amplifier can start-up in line driver mode (low gain setting).
The load diagnostic is insensitive to door-slam (slowly moving speaker due to slamming of
the car door) and to external interference such as crosstalk of relays switching in the
wiring harness; see
The load detection values are shown in
If only 4  speakers are connected, the low gain mode can be selected during the start-up
diagnostics. A shorted load is indicated until an impedance of 1.5  is reached. Even ‘soft’
shorts in the wiring harness will be detected.
Diagnostic information
Overvoltage protection (20 V)
Over voltage pre-warning (16 V) can be enabled if IB4[D3] = 1
Start-up diagnostic notification
Maximum temperature
protection active
Fig 8.
Fig 9.
high gain
low gain
Principle of start-up diagnostics
Start-up diagnostics load detection levels
SHORTED
Diagnostic information on pin DIAG
out +
All information provided in this document is subject to legal disclaimers.
GENERATOR
0.5 Ω
1.5 Ω
OFFSET
Figure
out −
Rev. 1 — 31 August 2011
1.5 Ω
3.2 Ω
8.
4 45 W power amplifier with multiple voltage regulator
Pin DIAG
yes
no
yes
FILTER
SPIKE
NORMAL
Figure
20 Ω
20 Ω
COMPARATORS
9.
80 Ω
80 Ω
LINE DRIVER
LOAD CONDITION
200 Ω
200 Ω
PROCESSOR
I
DOOR-SLAM
2
C-BUS BITS
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400 Ω
400 Ω
TDF8554J
© NXP B.V. 2011. All rights reserved.
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