CS43131 datasheet(38/156 Pages) CIRRUS

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DS1155F1

CS43131

4.5 Headphone Presence Detect and Output Load Detection

Before opening the HPINx switches, ramp down any active signal on HPINx pins to a voltage less than the VINOFF value

specified in Table 3-8. Similarly, the voltage cannot exceed the same voltage requirement before the switches are closed.

To prevent any pop on the headphone, the input should be muted during these transition. The CS43131 has ultralow offset

when muted. For pop-free transition on the headphone, it is expected that the source on HPINx pins have low offset to

ground when muted.

The recommended sequence to switch from CS43131 to HPINx is as follows:

1. Soft ramp content on CS43131 down to mute.

2. Set PDN_HP and wait for PDN_DONE_INT event.

3. If saving power is desired, switch MCLK_INT source to RCO.

4. Set HP_IN_EN.

The recommended sequence to switch from HPINx to CS43131 is as follows:

1. Setup CS43131 intended MCLK source for DAC operation (if needed)

2. Soft ramp content on HPINx down to mute.

3. Clear HP_IN_EN.

4. Switch MCLK_INT to the intended MCLK source when ready.

5. Clear PDN_HP.

The CS43131 has a HP_IN_LP setting to further reduce power when HPINx is enabled. This low power mode is only

supported if EXT_VCPFILT = 0. When selected, the HPINx path is placed into low power mode. This setting is only in

effect when HP_IN_EN = 1. It should only be set after HP_IN_EN = 1, and the user must wait for tHPIN_ON (EXT_

VCPFILT = 1) before enabling HP_IN_LP bit. HP_IN_LP should be cleared before HP_IN_EN is cleared. When HP_IN_

LP = 1, the maximum supported clock speed for I2C is 400 kHz.

4.5 Headphone Presence Detect and Output Load Detection

The CS43131 provides headphone presence-detect and load-detection functionalities.

4.5.1

Headphone Presence Detect

The CS43131 supports headphone presence-detect capability via the HP_DETECT sense pin. HP_DETECT is

debounced to filter out brief events before being reported to the corresponding presence-detect status bit and generating

an interrupt if appropriate.

4.5.1.1 Headphone Plug Types

The presence detect scheme is designed to support the following plug types:

• Tip-Ring-Sleeve (TRS). Consists of a segmented metal barrel with the tip connector used for HPOUTA, a ring

connector used for HPOUTB, and a sleeve connector used for HPGND.

• Tip-Ring-Ring-Sleeve (TRRS). Similar to TRS, with an additional ring connector for the HSIN connection. There are

two common pinouts for TRRS plugs:

— The tip is used for HPOUTA, the first ring for HPOUTB, the second ring for HSGND, and the sleeve for HSIN.

— An alternate pinout, OMTP (open mobile terminal platform), also called “China headset,” swaps the third and

fourth connections so that the second ring carries HSIN and the sleeve carries HSGND.

Note that if both TRRS plug types need to be supported at the same time, the CS43131 requires an additional IC to perform

the OMTP detect functions and to present the identified HSGND to the CS43131 HPREFx. However, the switch inside the

detect IC may degrade the CS43131 performance.

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