TDA7560

8/11

Figure 18. Power dissipation vs. ouput power

(Music/Speech Simulation)

Figure 19. Power dissipation vs. output power

(Music/Speech Simulation)

0123

45

6

Po (W)

5

10

15

20

25

30

Ptot (W)

Vs= 13.2 V

RL= 4 x 4 Ohm

CLIP START

GAUSSIAN NOISE

0

2

468

10

Po (W)

5

10

15

20

25

30

35

40

45

50

55

60

Ptot (W)

Vs= 13.2 V

RL= 4 x 2 Ohm

CLIP START

GAUSSIAN NOISE

3

DC Offset Detector

The TDA7560 The TDA7560 integrates a DC offset detector to avoid that an anomalous DC offset on the

inputs of the amplifier may be multiplied by the gain and result in a dangerous large offset on the outputs

which may lead to speakers damage for overheating.

The feature is enabled by the MUTE pin and works with the amplifier umuted and with no signal on the

inputs. The DC offset detection is signaled out on the HSD pin.

4

Application Hints (ref. to the circuit of fig. 4)

4.1 SVR

Besides its contribution to the ripple rejection, the SVR capacitor governs the turn ON/OFF time sequence

and, consequently, plays an essential role in the pop optimization during ON/OFF transients.To conve-

niently serve both needs, ITS MINIMUM RECOMMENDED VALUE IS 10

µF.

4.2 INPUT STAGE

The TDA7560's inputs are ground-compatible and can stand very high input signals (± 8Vpk) without any

performances degradation.

If the standard value for the input capacitors (0.1

µF) is adopted, the low frequency cut-off will amount to

16 Hz.

4.3 STAND-BY AND MUTING

STAND-BY and MUTING facilities are both CMOS-COMPATIBLE. In absence of true CMOS ports or mi-

croprocessors, a direct connection to Vs of these two pins is admissible but a 470 kOhm equivalent resis-

tance should present between the power supply and the muting and stand-by pins.

R-C cells have always to be used in order to smooth down the transitions for preventing any audible tran-

sient noises.

About the stand-by, the time constant to be assigned in order to obtain a virtually pop-free transition has

to be slower than 2.5V/ms.

4.4 HEATSINK DEFINITION

Under normal usage (4 Ohm speakers) the heatsink's thermal requirements have to be deduced from fig.

18, which reports the simulated power dissipation when real music/speech programmes are played out.

Noise with gaussian-distributed amplitude was employed for this simulation. Based on that, frequent clip-

ary conditions, the heatsink's thermal resistance should be approximately 2°C/W. This would avoid any

thermal shutdown occurence even after long-term and full-volume operation.