CS47L85 datasheet(238/370 Pages) CIRRUS

238 / 370 page

CS47L85

238

Rev 4.3

MICBn_ENA=0 :

MICBIASn is enabled periodically for measurement function

Measurement time

(100us to 500us)

MICD_RATE

(0ms to 512ms; 0.25ms default)

MICD_BIAS_STARTTIME

(0ms to 512ms; 0.25ms default)

time

MICBn_ENA=1 :

MICBIASn is enabled constantly

MICD_RATE

(0ms to 512ms; 0.25ms default)

time

Measurement time

(100us to 500us)

Figure 71 Microphone and Accessory Detect Timing

HEADPHONE DETECT

The CS47L85 headphone detection circuit measures the impedance of an external headphone load. This feature can be

used to set different gain levels or to apply other configuration settings according to the type of load connected. Separate

monitor pins are provided for headphone detection on the left and right channels of HPOUT1.

Headphone detection can be enabled on the HPDETL pin or the HPDETR pin. Under recommended configuration, these

pins provide measurement of the HPOUT1L and HPOUT1R loads respectively.

The headphone detect function can also be enabled on the MICDET1 pin or the MICDET2 pin. Note that, in this configuration,

any MICBIAS output that is connected to the selected MICDET pin must be disabled and floating (MICBn_ENA=0,

MICBn_DISCH=0).

The applicable headphone detection pin is selected using the ACCDET_MODE register. When MICDETn is selected

(ACCDET_MODE=100), the applicable MICDETn pin is determined by the ACCDET_SRC register, as described in Table

91.

The CS47L85 can only support one headphone or microphone detection function at any time. When the detection function

is not in use, it is recommended to set ACCDET_MODE=000.

Headphone detection on the selected channel is commanded by writing a ‘1’ to the HP_POLL register bit. The impedance

measurement range is configured using the HP_IMPEDANCE_RANGE register. This register should be set in accordance

with the expected load impedance.

Note that a number of separate measurements (for different impedance ranges) are typically required in order to determine

the load impedance; the recommended control sequence is described below.

Note that setting the HP_IMPEDANCE_RANGE register is not required for detection on the MICDETn pins

(ACCDET_MODE=100). Note also that the impedance measurement range, and measurement accuracy, in this mode are

different to the HPDETL and HPDETR measurement modes.

CS47L85 Datasheet(PDF) 238 Page - Cirrus Logic

CS47L85 Datasheet(HTML) 238 Page - Cirrus Logic

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL