TDA7560_05 Datasheet, PDF (8/11 Pages) STMicroelectronics – 4 X 45W QUAD BRIDGE CAR RADIO AMPLIFIER PLUS HSD

TDA7560
Figure 18. Power dissipation vs. ouput power
(Music/Speech Simulation)
30 ^{Ptot (W)}
Vs= 13.2 V
25 _{RL= 4 x 4 Ohm}
GAUSSIAN NOISE
20
CLIP START
15
10
5
0
1
2
3
4
5
6
Po (W)
Figure 19. Power dissipation vs. output power
(Music/Speech Simulation)
Ptot (W)
60
55
Vs= 13.2 V
RL= 4 x 2 Ohm
50 ^{GAUSSIAN NOISE}
45
40
CLIP START
35
30
25
20
15
10
5
0
2
4
6
8
10
Po (W)
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 10µF.
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 (0.1µF) 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-
ping occurence (worst-case) will cause Pdiss = 26W. Assuming T_amb = 70°C and T_CHIP = 150°C as bound-
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.
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