TDA7381_08 Datasheet, PDF (10/13 Pages) STMicroelectronics – 4 x 25W quad bridge car radio amplifier

Application hints
TDA7381
3.5
Stability and layout considerations
If properly layouted and hooked to standard carradio speakers, the TDA7381 will be
intrinsically stable with no need of external compensations such as output R-C cells. Due to
the high number of channels involved, this translates into a very remarkable components
saving if compared to similar devices on the market.
To simplify pc-board layout designs, each amplifier stage has its own power ground
externally accessible (pins 2,8,18,24) and one supply voltage pin for each couple of them.
Even more important, this makes it possible to achieve the highest possible degree of
separation among the channels, with remarkable benefits in terms of cross-talk and
distortion features.
About the layout grounding, it is particularly important to connect the AC-GND capacitor (C₅)
to the signal GND, as close as possible to the audio inputs ground: this will guarantee high
rejection of any common mode spurious signals.
The SVR capacitor (C₆) has also to be connected to the signal GND. Supply filtering
elements (C₇, C₈) have naturally to be connected to the power-ground and located as close
as possible to the Vs pins.
Pin 1, which is mechanically attached to the device’s tab, needs to be tied to the cleanest
power ground point in the pc-board, which is generally near the supply filtering capacitors.
Figure 10. An example of circuit able to distinguish between the two occurrences
VREF
25
T1
T2
TDA7385
T1 << T2
VREF ≥ VREF1 >> VREF2
-
+
VREF1
-
+
VREF2
CLIP DET. (TO GAIN
COMPRESSOR/
TONE CONTROL)
FAULT, THERMAL SHUTDOWN
(TO POWER SUPPLY
SECTION, μP VOLTAGE
REGULATOR, FLASHING SYSTEM)
D95AU305
10/13