CS47L35 datasheet(153/300 Pages) CIRRUS

153 / 300 page

DS1085F3

153

CS47L35

4.12 External Accessory Detection

4.12.2.5 Control Sequence for Jack Detect and MICDET Clamp

A summary of the jack detect and MICDET clamp functionality, and the recommended usage in typical applications, is

described as follows.

• On device power-up, and following reset, the MICDET clamp is active, due to the default setting of MICD_CLAMP_

OVD; this ensures no spurious output can occur during jack insertion. It is recommended to keep the MICDET clamp

active (MICD_CLAMP_OVD = 1) until after a jack insertion has been detected.

The MICDET_CLAMP_MODE field should be set according to the applicable JD1/JD2 signal configuration

(configured to assert the clamp when jack is removed).

• Jack insertion is indicated using the JD1/JD2 signals (assuming that the MICDET_CLAMP_MODE field has been

correctly set for the applicable JD1/JD2 signal configuration); the associated status bits can be read directly, or

associated signals can be unmasked as inputs to the interrupt controller.

After jack insertion has been detected, the applicable headset functions (headphone, microphone, accessory

detect) may then be enabled.

If the headset function requires MICBIAS to be enabled on the respective jack, the MICDET clamp should be

disabled (MICD_CLAMP_OVD = 0) immediately before enabling the MICBIAS (or immediately before enabling

MICD_ENA). Note that, if MICBIAS is not required on the respective jack, the clamp should not be disabled (e.g.,

for headphone-only operation).

• Jack removal is also indicated using the JD1/JD2 signals. The JD1/JD2 status bits can be read directly, or can be

unmasked as inputs to the interrupt controller. In this event, the MICDET clamp ensures fast and automatic silencing

of the jack outputs.

Table 4-75. MICDET Clamp and General-Purpose Switch Control

Address

Bit

Label

Default

Description

R65 (0x0041)

Sequence_

control

WSEQ_ENA_

MICD_

CLAMP_FALL

MICDET Clamp (Falling) Write Sequencer Select

0 = Disabled

1 = Enabled

WSEQ_ENA_

MICD_

CLAMP_RISE

MICDET Clamp (Rising) Write Sequencer Select

0 = Disabled

1 = Enabled

R710 (0x02C6)

Micd_Clamp_

control

4MICD_

CLAMP_OVD

MICDET Clamp Override

0 = Disabled

1 = Enabled (clamp active)

3:0 MICD_

CLAMP_

MODE[3:0]

0000

MICDET Clamp Mode

0x0 = Disabled

0x1 = Active (MICDET1 and MICDET2 are shorted

together)

0x2–0x3 = Reserved

0x4 = Active when JD1=0

0x5 = Active when JD1=1

0x6 = Active when JD2=0

0x7 = Active when JD2=1

0x8 = Active when JD1=0 or JD2=0

0x9 = Active when JD1=0 or JD2=1

0xA = Active when JD1=1 or JD2=0

0xB = Active when JD1=1 or JD2=1

0xC = Active when JD1=0 and JD2=0

0xD = Active when JD1=0 and JD2=1

0xE = Active when JD1=1 and JD2=0

0xF = Active when JD1=1 and JD2=1

R712 (0x02C8)

GP_Switch_1

1:0 SW1_

MODE[1:0]

General-purpose Switch control

00 = Disabled (open)

01 = Enabled (closed)

10 = Enabled when MICDET clamp is active

11 = Enabled when MICDET clamp is not active

R6278 (0x1886)

IRQ1_Raw_

Status_7

4MICD_

CLAMP_STS1

MICDET Clamp status

0 = Clamp not active

1 = Clamp active

R6534 (0x1986)

IRQ2_Raw_

Status_7

4MICD_

CLAMP_STS2

MICDET Clamp status

0 = Clamp not active

1 = Clamp active

R6662 (0x1A06)

Interrupt_

Debounce_7

4MICD_

CLAMP_DB

MICDET Clamp debounce

0 = Disabled

1 = Enabled

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