WM9704CFT/V Wolfson Microelectronics plc, WM9704CFT/V Datasheet - Page 36

• Manufacturer Part Number: WM9704CFT/V
• Description: AMC97 Audio and Modem Codec
• Manufacturer: Wolfson Microelectronics plc

WM9704M
RECOMMENDED EXTERNAL COMPONENTS VALUES
Table 23 External Component Values
RECOMMENDATIONS FOR 3.3V OPERATION
WOLFSON MICROELECTRONICS LTD
COMPONENT
REFERENCE
C34 and C35
C29 to C33
C5 to C17
C1 to C4
C18
C19
C20
C21
C22
C23
C24
C25
C26
C27
C28
XT
SUGGESTED
24.576 MHz
VALUE
470nF
100nF
0.1 F
0.1 F
0.1 F
0.1 F
10nF
10 F
10 F
10 F
10 F
47nF
10 F
22pF
1 F
The device’s performance with AVDD = 3.3V is shown in Electrical Characteristics.
In 3.3V analogue operation, mid-rail reference scales to 1.5V. All ADC and DAC references are 3/5
of their nominal 5V value. Input and output signals that are 1Vrms in 5V applications, scale to
660mVrms in 3.3V applications. If 1Vrms output is required, the mixer gain adjust PGAs need to be
increased by 3 times 1.5dB steps.
DESCRIPTION
De-coupling for DVDD and AVDD
AC coupling capacitors for setting DC level of analogue inputs to VCAP1.
Value chosen to give corner frequency below 20Hz for min 10K input impedance.
Reference de-coupling capacitors for ADC, DAC, Mixer and CAP2 references.
Ceramic type or similar.
3D low pass filter. This value sets nominal 100Hz.
3D high pass filter. This value sets nominal 1kHz.
Output AC coupling caps to remove VREF DC level from outputs.
Optional capacitors for better crystal frequency stability.
AC’97 master clock frequency. A bias resistor is not required, but if connected will not
affect operation if value is large (above 1M ).
PD Rev 3.2 January 2001
Production Data
ths
36