9397 750 14846
Koninklijke Philips Electronics N.V. 2005. All rights reserved.
Product data sheet
Rev. 02 — 3 June 2005
6 of 32
Philips Semiconductors
TDA8592J
I2C-bus controlled 4
× 50 W power amplier
7.2 Start-up and shut-down timing
A capacitor connected to pin SVR enables smooth start-up and shut-down, preventing the
amplier from producing audible clicks at switch-on or switch-off. The start-up and
shut-down times can be extended by increasing the capacitor value.
If the amplier is shut-down using pin STB, the amplier is muted, and the capacitor
connected to pin SVR discharges. The low current standby mode is activated 2 seconds
7.3 Power-on reset and supply voltage spikes
If the supply voltage drops too low to guarantee the integrity of the data in the I2C-bus
latches, the power-on reset cycle will start. All latches will be set to a pre-dened state, pin
DIAG will be pulled LOW to indicate that a power-on reset has occurred, and bit D7 of
data byte 2 is also set for the same reason. When D0 of instruction byte 1 is set, the
power-on ag resets, pin DIAG is released and the amplier will then enter its start-up
7.4 Diagnostic output
Pin DIAG indicates clipping, thermal protection pre-warning, short-circuit protection, low
and high battery voltage. Pin DIAG is an open-drain output, is active LOW, and must be
connected to an external voltage via an 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 I2C-bus.
7.5 Muting
A hard mute and a soft mute can both be performed via the I2C-bus. A hard mute mutes
the amplier within 0.5 ms. A soft mute mutes the amplier within 20 ms and is less
audible. A hard mute is also activated if a voltage of 8 V is applied to pin STB.
7.6 Temperature protection
If the average junction temperature rises to a temperature value that has been set via the
I2C-bus, a thermal protection pre-warning is activated making pin DIAG LOW. If the
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 xed:
only the temperature at which the thermal protection pre-warning signal occurs can be
specied by bit D4 in instruction byte 3. If 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 Tj(max).
7.7 Offset detection
Offset detection can only be performed when there is no input signal to the ampliers, 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 amplier is not muted.
Offset detection is always enabled.