CS47L35 datasheet(152/300 Pages) CIRRUS

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DS1085F3

CS47L35

4.12 External Accessory Detection

The control-write sequencer can be triggered by the MICDET clamp status. This is enabled using the WSEQ_ENA_MICD_

CLAMP_FALL and WSEQ_ENA_MICD_CLAMP_RISE bits; see Section 4.18 for further details.

4.12.2.3 Pop Suppression using General-Purpose Switch

In applications where a large decoupling capacitance is present on the MICBIAS output, the MICDET clamp function alone

may be unable to discharge the capacitor sufficiently to eliminate pops and clicks associated with jack insertion and

removal. In this case, it may be desirable to use the general-purpose switch within the CS47L35 to provide isolation from

the MICBIAS output; an example circuit is shown in Fig. 4-58.

The general-purpose switch is configured using SW1_MODE. This field allows the switch to be disabled, enabled, or

synchronized to the MICDET clamp status, as described in Table 4-75.

For jack pop suppression, it is recommended to set SW1_MODE = 11. In this case, the switch contacts are open whenever

the MICDET clamp is active, and the switch contacts are closed whenever the MICDET clamp is inactive.

Normal accessory functions are supported when the switch contacts (GPSWP and GPSWN) are closed, and the MICDET

clamp is inactive. Ground clamping of MICDET, and isolation of MICBIAS are achieved when the switch contacts are open,

and the MICDET clamp is active.

Note that the MICDET clamp function must also be configured appropriately when using this method of pop suppression

control.

Figure 4-58. General-Purpose Switch Circuit

4.12.2.4 MICDET Clamp Control Registers

The control registers associated with the MICDET clamp and general-purpose switch functions are described in

Table 4-75.

HPOUTFB1/

MICDET2

MICDET1/

HPOUTFB2

MICBIASnx

* IN1BLP, IN1BRP

R1 + R2 = 2.2 k

(±2%)

GPSWP

GPSWN

* Note: The Jack plug is shown

partially removed, with the MICDET1

pin in contact with the headphone load.

* see note

General-Purpose

Switch Control

SW1_MODE

MICDET

Clamp Control

MICD_CLAMP_OVD

MICD_CLAMP_MODE

MICD_CLAMP_STSx

MICD_CLAMP_DB

When the MICDET Clamp is active in the configuration

shown, the MICDET1 pin is grounded via the

headphone jack ground connection.

* Note that the IN1Bxx analog mic

channels are recommended with the

external accessory detect function

CS47L35

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