WM7331E

Rev 3.2

7

APPLICATIONS INFORMATION

RECOMMENDED EXTERNAL COMPONENTS

OUTPUT

VDD

GND

1

F

-

+

C

R

WM7331

Figure 1 WM7331 Recommended External Components

A DC-blocking output capacitor is required on the OUTPUT pin, as illustrated in Figure 1. A single

capacitor is required for a single-ended connection. The capacitor must be correctly selected as it

affects the cut-off frequency of the output path. A low cut-off frequency is desirable as it means there

is no significant filtering of the audio bandwidth.

The 3dB cut-off frequency of the output path is given by the equation below, where C is the output

capacitance and R is the input resistance of the other circuit.

3dB filter roll-off frequency =

1

2

RC

p

A typical recommended configuration, with 1uF DC-

blocking capacitor and 20kΩ minimum input circuit

impedance, gives a 3dB cut-off frequency of 10Hz or less. Tantalum electrolytic capacitors are

particularly suitable for the DC-blocking components as they offer high stability in a small package

size.