CS47L35 datasheet(228/300 Pages) CIRRUS

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DS1085F3

CS47L35

5 Applications

5.1 Recommended External Components

This section provides information on the recommended external components for use with the CS47L35.

5.1.1

Analog Input Paths

The CS47L35 supports up to six analog audio input connections. Each of these inputs is biased to the internal DC

reference, VREF. (Note that this reference voltage is present on the VREFC pin.) A DC-blocking capacitor is required for

each analog input pin used in the target application. The choice of capacitor is determined by the filter that is formed

between that capacitor and the impedance of the input pin. The circuit is shown in Fig. 5-1.

Figure 5-1. Audio Input Path DC-Blocking Capacitor

In accordance with the CS47L35 input pin resistance (see Table 3-5), a 1-

F capacitance for all input connections gives

good results in most cases, with a 3-dB cut-off frequency around 13 Hz.

Ceramic capacitors are suitable, but take care to ensure the desired capacitance is maintained at the AVDD operating

voltage. Also, ceramic capacitors may show microphonic effects, where vibrations and mechanical conditions give rise to

electrical signals. This is particularly problematic for microphone input paths where a large signal gain is required.

A single capacitor is required for a single-ended line or microphone input connection. For a differential input connection,

a DC-blocking capacitor is required on both input pins.

The external connections for single-ended and differential microphones, incorporating the CS47L35 microphone bias

circuit, are shown in Section 5.1.3; see Fig. 5-2.

5.1.2

DMIC Input Paths

The CS47L35 supports up to four channels of DMIC input; two channels of audio data can be multiplexed on each

DMICDATn pin. Each of these stereo pairs is clocked using the respective DMICCLKn pin.

Table 4-118. Device Reset and ID

Bit

Label

Default

Description

R0 (0x0000)

Software_Reset

15:0 SW_RST_DEV_

ID[15:0]

0x6360 Writing to this register resets all registers to their default state.

Reading from this register indicates Device ID 0x6360.

R1 (0x0001)

Hardware_

Revision

7:0

HW_

REVISION[7:0]

—

Hardware Device revision. This field is incremented for every new revision of the

device.

R2 (0x0002)

Software_Revision

7:0

SW_

REVISION[7:0]

—

Software Device revision. This field is incremented if software driver compatibility or

software feature support is changed.

= High-pass 3 dB cut-off frequency

2 RC



Input

VREF

PGA

–

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