TS4974_07 Datasheet, PDF (20/25 Pages) STMicroelectronics – 1W differential audio power amplifier with up/down digital volume control pins

Application information
TS4974
4.7
Pop performance
Due to its fully differential structure, the pop performance of the TS4974 is close to perfect.
However, due to mismatching between internal resistors R_in, R_feed, and external input
capacitors C_in, some noise might remain at startup. To eliminate the effect of mismatched
components, the TS4974 includes pop reduction circuitry. With this circuitry, the TS4974 is
close to zero pop for all possible common applications.
In addition, when the TS4974 is in standby mode, due to the high impedance output stage in
this configuration, no pop is heard.
4.8
Single-ended input configuration
It is possible to use the TS4974 in a single-ended input configuration. The schematic in
Figure 41 shows an example of this configuration.
Figure 41. Typical single-ended input application
VCC VCC
Volume DOWN _S1
Rpu1
470k
Rpu2
470k
VCC
Volume UP
S2
Cs
Rpd1 Rpd1
1µF
470k 470k
U1
DIGITAL VOLUME
CONTROL
Vin P1
Cin1
330nF
Cin2
330nF
1 Vin-
2 Vin+
3 BYP ASS
BIAS
Vout- 9
Speaker
+
Vout+ 8
8 Ohms
Cb
1µF
STBY
TS4974 DFN10
STBY
STBY control
4.9
Volume setting
The TS4974 features a digital volume control with an internal gain range of -33 dB up to
+12 dB, by steps of 3 dB. When the device is powered up from V_CC (and not from the
standby pin), an initial gain of -12dB is internally fixed. When standby mode is activated, the
gain value is memorized and held until standby is released.
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