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

Vb1 = 12 V, Vb2 = 6 V, Vb3 = 7 V

Ri  0.01  (internal resistor of power supply)

Recovery time from test start to tr is 1 s

tr = 2 ms

t1 = 1 ms (the shortest time, at cranking simulation power supply, is 5 ms)

t2 = 15 ms

t3 = 1 s

tf = 0.5 s

Vb1

V

Vb3

Vb2

tf

t3

t2

t1

tr

t