TDF8553J NXP Semiconductors, TDF8553J Datasheet - Page 9

• Manufacturer Part Number: TDF8553J
• Description: I2C-bus controlled 4 X 50 Watt power amplifier and multiple voltage regulator
• Manufacturer: NXP Semiconductors

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TDF8553J_1
Objective data sheet
8.5.1 Muting
8.5.2 Temperature protection
8.5.3 Offset detection
8.5.4 Speaker protection
8.5.5 Line driver mode
8.5 Amplifiers
external pull-up resistor. If a failure occurs, pin DIAG remains LOW during the failure and
no clipping information is available. The microcontroller can read the failure information
via the I
A hard mute and a soft mute can both be performed via the I
the amplifier within 0.5 ms. A soft mute mutes the amplifier within 20 ms and is less
audible. A hard mute is also activated if a voltage of 8 V is applied to pin STB.
If the average junction temperature rises to a temperature value that has been set via the
I
temperature continues to rise, all four channels will be muted to reduce the output power
(soft thermal clipping). The value at which the temperature mute control activates is fixed;
only the temperature at which the thermal protection pre-warning signal occurs can be
specified by bit D4 in instruction byte IB3. If implementing the temperature mute control
does not reduce the average junction temperature, all the power stages will be switched
off (muted) at the absolute maximum temperature T
Offset detection can only be performed when there is no input signal to the amplifiers, for
instance when the external digital signal processor is muted after a start-up. The output
voltage of each channel is measured and compared with a reference voltage. If the output
voltage of a channel is greater than the reference voltage, bit D2 of the associated data
byte is set and read by the microcontroller during a read instruction. Note that the value of
this bit is only meaningful when there is no input signal and the amplifier is not muted.
Offset detection is always enabled.
If one side of a speaker is connected to ground, a missing current protection is
implemented to prevent damage to the speaker. A fault condition is detected in a channel
when there is a mismatch between the power current in the high side and the power
current in the low side; during a fault condition the channel will be switched off.
The load status of each channel can be read via the I
the speaker connected to ground), short to V
and shorted load.
An amplifier can be used as a line driver by switching it to low gain mode. In normal mode,
the gain between single-ended input and differential output (across the load) is 26 dB. In
low-gain mode the gain between single-ended input and differential output is 20 dB.
2
C-bus, a thermal protection pre-warning is activated making pin DIAG LOW. If the
2
C-bus.
Rev. 01 — 3 December 2008
4
50 Watt power amplifier and multiple voltage regulator
P
(one side of the speaker connected to V
j(max)
2
C-bus: short to ground (one side of
.
2
C-bus. A hard mute mutes
TDF8553J
© NXP B.V. 2008. All rights reserved.
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