TS488 Datasheet, PDF (24/32 Pages) STMicroelectronics – Pop-free 120mW stereo headphone amplifier

Application information
TS488-TS489
4.4
Figure 79. Lower cut-off frequency vs. Figure 80. Lower cut-off frequency vs.
input capacitor
output capacitor
10k
10k
Rin=10kΩ
Rin=20kΩ
1k
Rin=50kΩ
1k
Rin=100kΩ
100
100
R =16Ω
L
R =32Ω
L
R =600Ω
L
10
10
1
10
100
1000
0.1
1
10
100
1000
Cin (nF)
Cout (μF)
Note:
In case F_CL is kept the same for calculation, It must be taken in account that the
1st order high-pass filter on the input and the 1st order high-pass filter on the
output create a 2nd order high-pass filter in the audio signal path with an
attenuation 6dB on F_CL and a roll-off 40db⁄ decade.
Higher cut-off frequency
In the high frequency region, you can limit the bandwidth by adding a capacitor C_feed in
parallel with R_feed. It forms a low-pass filter with a -3dB cut-off frequency F_CH. Assuming
that F_CH is highest frequency to be amplified (with a 3dB attenuation), the maximum value of
C_feed is:
F_CH
=
------------------------¹--------------------------
2π ⋅ R_feed ⋅ C_feed
Figure 81. Higher cut-off frequency vs. feedback capacitor
100k
Rfeed=10kΩ
Rfeed=20kΩ
10k
Rfeed=40kΩ
1k
Rfeed=80kΩ
100
0.01
0.1
1
10
100
Cfeed (μF)
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