TS4872 Datasheet, PDF (25/29 Pages) STMicroelectronics – RAIL TO RAIL INPUT/OUTPUT 1W AUDIO POWER AMPLIFIER WITH STANDBY MODE

TS4872
Designator
C10
C12
S1, S2, S6, S7
S8
J1
U1
Part Type
Short Circuit
1µF
2mm insulated Plug
10.16mm pitch
2 pts connector 2.54mm
pitch
SMB Plug
TS4872IJ
Application n°4 : Differential inputs BTL power
amplifier.
In this configuration, we need to place these
components : R1, R4, R5, R6, R7, C4, C5, C12.
We have also : R4 = R5, R1 = R6, C4 = C5.
The gain of the amplifier is :
GVDIFF = 2 ^RR-----14-- (Pos. Input - Neg.Input)
For a 20Hz to 20kHz bandwidth and 6dB gain BTL
power amplifier you could follow the bill of material
below.
Components :
Designator
R1
R4
R5
R6
R7
C4
C5
Part Type
22k / 0.125W
22k / 0.125W
22k / 0.125W
22k / 0.125W
330k / 0.125W
470nF
470nF
Designator
C6
C7
C9
C10
C12
S1, S2, S6, S7
S8
J1, J3
U1
Part Type
100µF
100nF
Short Circuit
Short Circuit
1µF
2mm insulated Plug
10.16mm pitch
2 pts connector 2.54mm
pitch
SMB Plug
TS4872IJ
s Note on how to use the PSRR curves
(page 8)
We have finished a design and we have chosen
the components :
s Rin=Rfeed=22kΩ
s Cin=100nF
s Cb=1µF
Now, on fig. 13, we can see the PSRR (input
grounded) vs frequency curves. At 217Hz we have
a PSRR value of -36dB.
In reality we want a value about -70dB. So, we
need a gain of 34dB !
Now, on fig. 12 we can see the effect of Cb on the
PSRR (input grounded) vs. frequency. With
Cb=100µF, we can reach the -70dB value.
The process to obtain the final curve (Cb=100µF,
Cin=100nF, Rin=Rfeed=22kΩ) is a simple transfer
point by point on each frequency of the curve on
fig. 13 to the curve on fig. 12.
The measurement results is shown on figure 84.
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