Preliminary Technical Data

WM3100

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PTD, October 2010, Rev 2.0

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DEVICE DESCRIPTION

INTRODUCTION

The WM3100 is a high-performance stereo line driver designed for Digital televisions, DVD, Blu-ray,

set-top box and gaming applications. It is packaged in a 14-pin SOIC.

supply.

The inputs and outputs to the WM3100 are ground-referenced; an integrated charge pump circuit

generates the required negative supply rail from the single VDD supply.

The analogue outputs can be muted under control of a digital logic input. The outputs can also be set

to a high impedance state, supporting applications where a common external connector is used as

an input and an output.

INPUT SIGNAL PATH

The WM3100 supports two line input channels, which can each be used in single-ended or

differential circuit configurations, as illustrated in Figure 1, Figure 2 and Figure 3. The signal gain is

6.4dB in each case.

The input capacitor must be correctly selected as it affects the low cut-off frequency of the input

circuit. A low cut-off frequency is desirable as it means that there is no significant filtering of the 20Hz

to 20kHz audio frequency bandwidth.

Typically, the 3dB cut-off frequency for the line input should be around 10Hz. The WM3100 input

impedance is 24k

Ω (see “Electrical Characteristics”). Using the equations below, it follows that the

AC coupling capacitors should be approximately 1

μF (which gives a 3dB cut-off frequency around

7Hz).

Figure 1 Single-Ended Line Input (Inverting)

Figure 2 Single-Ended Line Input (Non-Inverting)