Philips Semiconductors
Product specification
2 × 25 W BTL stereo car radio power amplifier
with differential inputs and diagnostic outputs
TDA8566Q
Short-circuit diagnostic (pin 15)
Temperature pre-warning (pin 15)
When a short-circuit occurs at one or more outputs to
ground or to the supply voltage, the output stages are
switched off until the short-circuit is removed and the
device is switched on again (with a delay of approximately
20 ms after the removal of the short-circuit). During this
short-circuit condition, pin 15 is continuously low.
When the junction temperature (Tvj) reaches 145 °C,
pin 15 will become continuously low.
Open-collector outputs
Pins 4 and 15 are open-collector outputs, therefore more
devices can be tied together. Pins 4 and 15 can also be
tied together. An external pull-up resistor is required.
When a short-circuit occurs across the load of one or both
channels, the output stages are switched off for
approximately 20 ms. After approximately 50 µs the load
condition is again checked to see if the short-circuit is still
present. Due to this duty cycle of 50 µs/20 ms the average
current consumption during this short-circuit condition is
very low (approximately 40 mA). During this short-circuit
condition, pin 15 is low for 20 ms and high for 50 µs (see
Fig.4). The power dissipation in any short-circuit condition
is very low.
Differential inputs
The input stage is a high-impedance fully differential
balanced input stage that is also capable of operating in a
single-ended mode with one of the inputs capacitively
coupled to an audio ground. It should be noted that if a
source resistance is added (input voltage dividers) the
CMRR degrades to lower values.
MGD103
V
out
handbook, halfpage
0
V
4
V
P
0
t
Fig.3 Clip detection waveforms.
current
in
handbook, full pagewidth
MGA707
output
stage
t
short-circuit over the load
V
15
20 ms
V
P
t
50 µs
Fig.4 Short-circuit diagnostic timing diagram.
5
1998 Sep 23
NXP [ NXP ]
