Production Data
WM9715L
RECOMMENDED COMPONENTS VALUES
COMPONENT
REFERENCE
SUGGESTED
VALUE
DESCRIPTION
C1 – C6
C7 – C8
100nF
10uF
De-coupling for DBVDD,DCVDD,TPVDD,AVDD,SPKVDD,HPVDD
Reservoir capacitor for DVDD, AVDD. Should the supplies use separate sources then
additional capacitors will be required of each additional source.
C9
C10
100nF
10uF
De-coupling for CAP2.
Reservoir capacitor for CAP2
C11
100nF
10uF
De-coupling for VREF
C12
Reservoir capacitor for VREF
C13
100nF
10uF
De-coupling for MICBIAS – Not required if MICBIAS output is not used
Reservoir capacitor for MICBIAS – Not required if MICBIAS output is not used
Required when used with a parallel resonant crystal.
AC coupling capacitors
C14
C27 & C28
C15 – C20
C21 – C23
C24 – C26
R1
22pF
1uF
2.2uF
220µF
100kΩ
24.576MHz
Output AC coupling capacitors to remove VREF DC level from outputs
Output AC coupling capacitors to remove VREF DC level from outputs.
Pull-up resistor, ensures that all circuit blocks are OFF by default
XT
AC’97 master clock frequency. A bias resistor is not required but if connected will not
affect operation if the value is large (above 1MΩ)
Table 44 External Components Descriptions
Note:
3 For Capacitors C7, C8, C10, C12 and C14 it is recommended that very low ESR components are used.
LINE OUTPUT
The headphone outputs, HPOUTL and HPOUTR, can be used as stereo line outputs. The speaker
outputs, LOUT2 and ROUT2, can also be used as line outputs, if LOUT2 is not inverted for BTL
operation (INV = 0). Recommended external components are shown below.
Figure 24 Recommended Circuit for Line Output
The DC blocking capacitors and the load resistance together determine the lower cut-off frequency,
fc. Assuming a 10 kΩ load and C1, C2 = 10µF:
fc = 1 / 2π (RL+R1) C1 = 1 / (2π x 10.1kΩ x 1µF) = 16 Hz
Increasing the capacitance lowers fc, improving the bass response. Smaller values of C1 and C2 will
diminish the bass response. The function of R1 and R2 is to protect the line outputs from damage
when used improperly.
PD Rev 4.0 December 2007
w
73
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
