Low voltage "start-stop" operation TDA7565
16/19 Doc ID 9800 Rev 5
6 Low voltage "start-stop" operation
The most recent OEM specification are requiring automatic stop of car engine at traffic lights
in order to reduce emissions of polluting substances. The TDA7565, thanks to its integrated
switching voltage converter, allows a continuous operation when battery falls down to 6/7 V
during such conditions, without producing pop noise. The maximum system power will be
reduced accordingly.
The internal converter must be enabled and programmed in order to supply 15 V (D3 (IB2) = 0;
D6 (IB2) = 0). The suggested voltage frequency switching is 150 kHz (D6 (IB1) = 1; D7 (IB1) = 0).
The following curve is a worst case condition for a start-stop system. The TDA7565, with the
switching converter powered on, can sustain this cranking curve without any audio signal
interruption.
Figure 7. Worst case condition for a start-stop system diagram
V
b1
= 12 V, V
b2
= 6 V, V
b3
= 7 V
R
i
0.01 (internal resistor of power supply)
Recovery time from test start to tr is 1 s
t
r
= 2 ms
t
1
= 1 ms (the shortest time, at cranking simulation power supply, is 5 ms)
t
2
= 15 ms
t
3
= 1 s
t
f
= 0.5 s
V
b1
V
V
b3
V
b2
t
f
t
3
t
2
t
1
t
r
t
