Cirrus-logic AN241 Bedienungsanleitung PDF herunterladen (Seite 7)

AN241

capacitors with a large voltage coefficient (such as general purpose ceramics) since they can degrade

signal linearity.

4. Single-Ended Input Buffer with Dedicated Reference Pins

4.1 Applicable Converters

A single-ended analog input buffer with dedicated reference pins is ideal for use with the following Cirrus

Logic audio converters:

- CS5351

- CS4271

- CS42528/26/18/16 (Note: Full performance will not be realized with a single-ended implementation.)

- CS42428/26/18/16 (Note: Full performance will not be realized with a single-ended implementation.)

4.2 Introduction

A single-ended signal consists of only one signal line and hence requires only one input pin. Some con-

verters have a dedicated reference pin for each channel, as well as an on-chip reference. These pins are

typically labeled VQx. Please check the datsheet for the particular converter to determine the naming con-

vention of the VQx pins.

4.3 Recommended Filter Topology #1

Figure 4 shows a single-ended analog input buffer with dedicated reference pins. This filter implements

one op-amp per channel, and uses a third op-amp to properly bias the analog inputs and independent

channel reference pins. This buffer provides proper biasing, isolation from the switched capacitor cur-

rents, low output impedance, and anti-alias filtering.

Figure 4. Single-Ended Input Buffer with Dedicated Reference Pins (Example #1)

Ω

µ µ

Ω

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Cirrus-logic AN241 Bedienungsanleitung Seite 7