WM8714
Production Data
RECOMMENDED ANALOGUE LOW PASS FILTER (OPTIONAL)
4.7kΩ
4.7k
Ω
+VS
_
51
Ω
10uF
1.8kΩ
7.5KΩ
+
+
-VS
1.0nF
680pF
47kΩ
Figure 7 Recommended 2nd Order Low Pass Filter (Optional)
An external low pass filter is recommended (see Figure 7) if the device is driving a wideband
amplifier. In some applications, a passive RC filter may be adequate.
PCB LAYOUT
1. Place all supply decoupling capacitors as close as possible to their respective supply pins
and provide a low impedance path from the capacitors to the appropriate ground.
2. Separate analogue and digital ground planes should be situated under respective analogue
and digital device pins.
3. Digital input signals should be screened from each other and from other sources of noise to
avoid cross-talk and interference. They should also run over the digital ground plane to avoid
introducing unwanted noise into the analogue ground plane.
4. Analogue output signal tracks should be kept as short as possible and over the analogue
ground plane reducing the possibility of losing signal quality.
PD Rev 4.0 November 2004
15
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
