Philips TDA8566 - Manual (Page 7)

TDA8566_6 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 06 — 15 October 2007 7 of 21
NXP Semiconductors
TDA8566
2
×
40 W/2
Ω
stereo BTL car radio power amplifier
7.3 Short-circuit diagnostic (pin DIAG)
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 DIAG is continuously LOW.
When a short-circuit occurs across the load of one or both channels, the output stages are
switched off for approximately 20 ms. After that time the load condition is checked during
approximately 50
µ
s to see whether the short-circuit is still present. Due to this duty cycle
of 50
µ
s/20 ms the average current consumption during the short-circuit condition is very
low (approximately 40 mA). During this condition, pin DIAG is LOW for 20 ms and HIGH
for 50
µ
s; see Figure 6 . The power dissipation in any short-circuit condition is very low.
7.4 Temperature pre-warning (pin DIAG)
When the virtual junction temperature (T
vj
) reaches 145
°
C, pin DIAG will become
continuously LOW.
7.5 Open-collector diagnostic outputs
Pins DIAG and CLIP are open-collector outputs, therefore more devices can be tied
together. Pins DIAG and CLIP can also be tied together. An external pull-up resistor is
required.
Fig 5. Clip detection waveforms
0
V
O
(V)
V
CLIP
(V)
0
t (s)
mgu357
Fig 6. Short-circuit diagnostic timing diagram
mgu360
short-circuit over the load
20 ms
50
µ
s
t (s)
t (s)
V
DIAG
(V)
current
in
output
stage