TDF8555J NXP Semiconductors, TDF8555J Datasheet - Page 13

• Manufacturer Part Number: TDF8555J
• Description: The TDF8555J 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
TDF8555J
Product data sheet
7.4.3 Speaker fault detection
7.4.4 Overvoltage warning and load dump protection
There are two protection features available to prevent damage to the speaker if one side
of the speaker is connected to ground.
If the battery voltage V
the output stages of the amplifier to protect the output transistors. The overvoltage
pre-warning bit is set when the supply voltage level exceeds the value of V
Although the amplifier switches off the output stages, the device remains operational
during load dump conditions (maximum value of V
50 ms, rise time > 2.5 ms). The occurrence of the load dump situation can last for a longer
period of time without damaging the device. Provided that the I
levels specified, communication with the I
possible and the status of the channel outputs can be read.
Fig 6.
•
•
A check for a speaker fault operates during start-up. This is included in the check for a
short to ground; the channel that has the speaker fault is switched off. If the short to
ground bit is set, it can mean either a short to ground or a speaker fault. At start-up it
is difficult to distinguish between a speaker fault and a short to ground. The amplifier
is protected against both, but the speaker fault bit is not always set.
A check for a speaker fault operates continuously. If a speaker fault is detected and
IB5[D3] = 1, bit D3 in registers DB1 to DB4 is set but the amplifier is not switched off
and pin DIAG is not pulled LOW.
(1) Amplifier output stage.
Test circuit for loss-of-V
All information provided in this document is subject to legal disclaimers.
V P
Loss-of-V
Rev. 1 — 15 September 2011
P
C buffer
116 mF
exceeds the maximum value of V
P
tester
V pulse
4 45 W power amplifier with multiple voltage regulator
IRF5305
PMOS
P
test
2
2200 μF
C-bus bus during load dump situations remains
R S
P
at load dump protection; duration
DUT in application
th(ovp)
2
, the device switches off
C-bus supply is within the
TDF8555J
(1)
© NXP B.V. 2011. All rights reserved.
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P(ovp)pwarn
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