TS4974_07 STMICROELECTRONICS [STMicroelectronics], TS4974_07 Datasheet - Page 22

• Manufacturer Part Number: TS4974_07
• Description: 1W differential audio power amplifier with up/down digital volume control pins
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Application information
4.10
22/25
Notes on PSRR measurement
What is the PSRR?
The PSRR is the power supply rejection ratio. The PSRR of a device is the ratio between a
power supply disturbance and the result on the output. In other words, the PSRR is the
ability of a device to minimize the impact of power supply disturbance to the output.
How is the PSRR measured?
The PSRR is measured as shown in
Figure 43. PSRR measurement
Principles of operation
●
●
●
The PSRR value for each frequency is calculated as:
RMS is an rms selective measurement.
The DC voltage supply (V
The AC sinusoidal ripple voltage (V
No bypasss capacitor Cs is used
10 Ohms
10 Ohms
Cin1
330nF
Cin2
330nF
Volume DOWN
Volume UP
PSRR
Cb
1µF
1
2
3
CC
TS4974 DFN10
U1
Vin-
Vin+
BYP ASS
) is fixed
S1
S2
=
DIGITAL VOLUME
Figure
VCC
20
CONTROL
Rpu1
470k
STBY control
×
ripple
BIAS
STBY
Log
VCC
STBY
43.
) is fixed
Rpu2
470k
--------------------------------- -
RMS
RMS
Rpd1
470k
(
(
Vripple
Output
Rpd1
470k
+
)
)
(
dB
)
Vout+
Vout-
Vripple
Vcc
9
8
RL
8 Ohms
TS4974