CS43131 datasheet(39/156 Pages) CIRRUS

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DS1155F1

CS43131

4.5 Headphone Presence Detect and Output Load Detection

4.5.1.2 Headphone Detect Methods

CS43131 can detect the presence or absence of a plug. For a headphone-presence detect, a sense pin is connected to

a terminal on the receptacle such that, if no plug is inserted, the pin is floating. If a plug is inserted, the pin is shorted to

the tip (T) terminal. The presence detect function is accomplished by having a small current source inside the CS43131

to pull up the pin if it is left floating (no plug). If a plug is inserted and the sense pin is shorted to HPOUTA, when HP amp

is powered down, it is assumed that the sense pin is pulled low via clamps at the HP amp output. If the HP amp is running,

the sense pin is shorted to the output signal and, therefore, is pulled below a certain threshold via the output stage of the

HP amp. Thus, a low level at the sense pin indicates plug inserted, and a high level at the sense pin indicates plug

removed.

4.5.1.3 Headphone Detect Registers

This section describes the behavior and interaction of the headphone-detect debounce register fields. See Fig. 4-10 for

reference.

Figure 4-10. Headphone Detect Block Diagram

• HPDETECT_CTRL configures the operation of the HP detect circuit.

• HPDETECT_INV inverts the signal from the HP detect circuit.

• HPDETECT_FALL_DBC_TIME configures the HP_DETECT falling debounce time.

• HPDETECT_RISE_DBC_TIME configures the HP_DETECT rising debounce time.

• HPDETECT_PLUG_DBC shows the falling-edge-debounced version of HP_DETECT signal.

• HPDETECT_UNPLUG_DBC shows the rising-edge-debounced version of HP_DETECT signal.

• HPDETECT_PLUG_INT shows the headphone plug-in event status.

• HPDETECT_UNPLUG_INT shows the headphone unplug event status.

• HPDETECT_PLUG_INT_MASK is the interrupt mask of headphone plug-in event status.

• HPDETECT_UNPLUG_INT_MASK is the interrupt mask of headphone unplug event status.

4.5.1.4 Headphone Detect and Interrupts Setup Instructions

The following steps are required for activation of headphone-detect debounce interrupt status:

1. Ensure the I2C is ready to respond to control port command.

2. Clear the interrupt masks.

3. Write to HPDETECT_RISE_DBC_TIME and HPDETECT_FALL_DBC_TIME (see p. 131) to enable debounce for

presence detect plug/unplug.

4. Set HPDETECT_CTRL to 11 to enable the HPDETECT functions.

HP_DETECT

HP Detect Block

Delay

HP Detect

Plug/Unplug

Detect

HP Detect

Plug/Unplug Interrupt

Mask

HP Detect

Plug/Unplug Interrupt

Status

Interrupt Handler Block

INT

Read

Clears INT

FALL_DEBOUNCE

RISE DEBOUNCE

Delay

HP Detect

Debounced Status

HPDETECT_CTRL p. 131

HPDETECT_PLUG_INT

p. 134

HPDETECT_UNPLUG_

INT p. 134

HPDETECT_RISE_DBC_TIME p. 131

HPDETECT_FALL_DBC_TIME p. 131

HPDETECT_INV

p. 131

HPDETECT_PLUG_DBC p. 131

HPDETECT_UNPLUG_DBC

p. 132

HPDETECT_PLUG_INT_

MASK p. 137

HPDETECT_UNPLUG_

INT_MASK p. 137

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