Functional Description - Philips TDA8586 Datasheet

Philips Semiconductors
Power amplifier with load detection and
auto BTL/SE selection

FUNCTIONAL DESCRIPTION

The TDA8586 is a multi-purpose power amplifier with four
amplifiers and 2 buffer stages, which can be connected in
the following configurations with high output power and
low distortion:
Dual Bridge-Tied Load (BTL) amplifiers
Quad Single-Ended (SE) amplifiers.
In the BTL mode of operation, the 2 buffer amplifiers act as
inverting amplifiers to complete the bridge across the front
amplifiers (OUT1 and OUT3) and the rear outputs (OUT2
and OUT4) enter a high-impedance state.
In the SE mode of operation, the buffers act as an AC
ground path thereby eliminating the need for series
capacitors on the speaker outputs.
Diagnostics:
While the IC is in the mute mode, the diagnostic output
will signal the mode of operation when the IC is not
overruled
In the on mode the diagnostic output will signal any fault
in the IC or if the output of any amplifier is clipping with
a distortion of 10% (or 2% depending on selected
clip-mode).
Special attention is given to the dynamic behaviour as
follows:
Noise suppression during engine start
No plops when switching from standby to on
Slow offset change between mute and on (controlled by
MSO pin)
Low noise levels, which are independent of the supply
voltage.
Protections are included to avoid the IC being damaged at:
Over temperature: T
Short-circuit of the output pin(s) to ground or supply rail.
When short-circuited, the power dissipation is limited
ESD protection (Human Body Model 3000 V and
Machine Model 300 V).
2001 Jul 23
> 150 C
j
The presence of the load is measured after the transition
between standby and mute. The IC will determine if there
is an acceptable load on both outputs (OUT2 and OUT4).
If both outputs are unloaded, the IC will switch to a
2 speaker mode of operation (BTL mode), unless it is
overruled.
There are two options to overrule:
1. Before transition from mute to on, after a load
detection, pulling the diagnostic output above 9.5 V
will force the IC into 4 speaker mode
2. TDA8586TH: pulling the OVERRULE pin according
pinning table.
Care should be taken with the OVERRULE function as it
works during the on mode. If there is a 2 or 4 speaker
mode change during the on mode a large plop can be
heard on the speakers.
The ACREF input (common signal input) acts with the four
signal inputs (IN1 to IN4) to provide quasi differential
inputs. A capacitor must be connected to this pin of which
the ground pin should be connected to the ground at the
signal source (usually the ground at the audio signal
processor). This capacitor has a dual function. During the
speaker detection, the signal ground capacitor is used to
set the time constant of the measurement (and thus
determines the minimum required switch-on time).
The capacitor on the MSO pin allows the integrate function
to provide immunity to outside noises during load
detection.
8
Preliminary specification
TDA8586