TS4990 Datasheet, PDF (23/33 Pages) STMicroelectronics – 1W AUDIO POWER AMPLIFIER WITH ACTIVE LOW STANDBY MODE

TS4990
Application information
4.9
Application example: differential input, BTL power amplifier
The schematics in Figure 64 show how to configure the TS4990 to work in differential input
mode. The gain of the amplifier is:
G_VDIFF
=
2
R_-----2-
R₁
In order to reach the best performance of the differential function, R₁ and R₂ should be
matched at 1% max.
Figure 64. Differential input amplifier configuration
R2
Vcc
Cs
Neg. Input
Pos. Input
Cin _R1
Cin _R1
Vin-
-
Vin+
+
Vout 1
Speaker
8 Ohms
R2
Standby
Control
Cb
Bypass
Standby
Bias
-
AV = -1
+
Vout 2
TS4990
Note:
The input capacitor C_in can be calculated by the following formula using the -3 dB lower
frequency required. (F_L is the lower frequency required).
C_i
n
≈
----------¹----------
2πR₁F_L
(F)
This formula is true only if:
F_CB = ₂----_π----₍--_R-----₁----+¹-----_R----₂---₎---_C----_B-- (Hz)
is 5 times lower than F_L.
Doc ID 9309 Rev 13
23/33