WM9712L datasheet(72/77 Pages) WOLFSON

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WM9712L

Production Data

PD Rev 4.5 August 2006

RECOMMENDED COMPONENTS VALUES

COMPONENT

REFERENCE

SUGGESTED

VALUE

DESCRIPTION

C1 - C6

100nF

De-coupling for DBVDD,DCVDD,TPVDD,AVDD,SPKVDD,HPVDD

C7 - C8

10uF

Reservoir capacitor for DVDD, AVDD. Should the supplies use separate sources then

additional capacitors will be required of each additional source.

100nF

De-coupling for CAP2.

C10

10uF

Reservoir capacitor for CAP2

C11

100nF

De-coupling for VREF

C12

10uF

Reservoir capacitor for VREF

C13

100nF

De-coupling for MICBIAS - Not required if MICBIAS output is not used

C14

10uF

Reservoir capacitor for MICBIAS - Not required if MICBIAS output is not used

C27 & C28

22pF

Required when used with a parallel resonant crystal.

C15 - C20

1uF

AC coupling capacitors

C21 - C23

2.2uF

Output AC coupling capacitors to remove VREF DC level from outputs

C24 - C26

220

µF

Output AC coupling capacitors to remove VREF DC level from outputs.

100k

Ω

Pull-up resistor, ensures that all circuit blocks are OFF by default

100k

Ω

Pull down resistor, ensures that all circuit blocks are ON by default

24.576MHz

AC'97 master clock frequency. A bias resistor is not required but if connected will not

affect operation if the value is large (above 1M

Ω)

Table 46 External Components Descriptions

Note:

1. 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.

HPGND

LINE-OUT

SOCKET

(LEFT)

1uF

100 Ohm

HPOUTL /

LOUT2

HPOUTR /

ROUT2

WM9712L

100 Ohm

LINE-OUT

SOCKET

(RIGHT)

1uF

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 k

Ω load and C1, C2 = 10µF:

fc = 1 / 2

π (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.

WM9712L Datasheet(PDF) 72 Page - Wolfson Microelectronics plc

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