Cirrus Logic CS42L42 Manual page 40

Fig. 4-12 shows the headphone-to-analog input electrical path.
HSBIAS_
FILT_REF
HSBIAS_
Based on Fig. 4-12, the formula in
Eq. 4-2 gives an isolation of +69.03 dB, given the following:
= 30 
• R
L
= 0.0053 
• R
T2
= 0.1 
• R
COM2
• R = 2.21 k
BIAS
• R = 2.21 k
MIC
Fig. 4-13 shows the headphone electrical path.
DS1083F2
From
HPOUTA
DAC
From
HPOUTB
DAC
R HS3
SW
HS3_REF
R HS4
BIAS
HS_BIAS
HSIN–
FILT
HSIN+
Figure 4-12. Headphone-to-ADC Electrical Path
Eq. 4-2 measures headphone-to-analog isolation.
Isolation
Equation 4-2. Headphone-to-Analog Isolation Equation
R
2
R
1
R
1
R
2
R
2
R
1
R
1
R
2
Figure 4-13. Headphone Electrical Path
4.5 System Headphone Parasitic Resistances
R R
T1 T2
R
T3
R
T4
R
MIC
 2 
 
----- -
=
20 log R
 
T2
R
L
HPSENSA
HPOUTA
HSx_REF
R R R
COM1 T1
R
R HSx
T2
SW
HPOUTB
HPSENSB
R
R
L
L
R
COM2
R
L
COM2
R
L
CS42L42
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