TS4984 Datasheet, PDF (24/29 Pages) STMicroelectronics – 2 x 1W Stereo audio power amplifier with active low standby mode

TS4984
Application Information
4.9 Application example: Differential-input BTL power stereo amplifier
The schematic in Figure 69 shows how to design the TS4984 to work in differential-input mode. For this
discussion, only the left-channel amplifier will be referred to.
Let:
R_1R = R_2L = R₁, R_2R = R_2L = R₂
C_inR = C_inL = C_in
The gain of the amplifier is:
Gvdif
=
2
×
R_-----2--
R1
In order to reach the optimal performance of the differential function, R₁ and R₂ should be matched at 1%
maximum.
Figure 69: Differential input amplifier configuration
Neg. Input LEFT CinL
R1L
Pos. Input LEFT CinL
R1L
R2L
StandBy
Control
R2L
VCC
IN-L _-
IN+L ₊
Cs
TS4984
VO-L
StandBy _Bias
BypassL
-
AV = -1
+
VO+ L
LEFT Speaker
8 Ohms
Pos. Input RIGHT CinR
R2R
R1R
Neg. Input RIGHT CinR
R1R
IN+R ₊
IN-R _-
BypassR
Cb
VO-R
-
AV = -1
+
VO+R
RIGHT Speaker
8 Ohms
R2R
24/29