CS47L85 datasheet(234/370 Pages) CIRRUS

234 / 370 page

CS47L85

234

Rev 4.3

and up to 6 push-buttons. Each measurement level can be enabled or disabled independently; this provides flexibility

according to the required thresholds, and offers a faster measurement time in some applications. The MICD_LVL_SEL

Note that the impedance levels quoted in the MICD_LVL description assume that a microphone (475

Ω to 30kΩ impedance)

is also present on the MICDET pin. The limits quoted in the “Electrical Characteristics” refer to the combined effective

impedance on the MICDET pin. Typical external components are described in the “Applications Information” section.

When the ADC measurement mode is selected (ACCDET_MODE=111), the detection function must be disabled before the

measurement can be read. When the CS47L85 indicates valid data (MICD_VALID=1), the detection must be disabled by

setting MICD_ENA=0.

The

ADC

measurement

mode

generates

two

output

results,

contained

within

the

MICDET_ADCVAL

and

MICDET_ADCVAL_DIFF registers. These registers contain the most recent measurement value (MICDET_ADCVAL) and

the measurement difference value (MICDET_ADCVAL_DIFF). The difference value indicates the difference between the

latest measurement and the previous measurement; this can be used to determine whether the measurement is stable and

reliable.

Note that the MICDET_ADCVAL and MICDET_ADCVAL_DIFF registers do not follow a linear coding. The appropriate test

condition for accepting the measurement value (or for re-scheduling the measurement) will vary depending on the application

requirements, and depending on the expected impedance value.

The microphone detection function is an input to the Interrupt control circuit and can be used to trigger an Interrupt event

every time an accessory insertion, removal or impedance change is detected. See “Interrupts” for further details.

The register fields associated with Microphone Detection (or other accessories) are described in Table 88. The external

circuit configuration is illustrated in Figure 70.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R659

(0293h)

Accessory_

Detect_Mod

e_1

ACCDET_SRC

Accessory Detect / Headphone

Feedback pin select

0 = Accessory detect on MICDET1,

Headphone ground feedback on

HPOUT1FB1

1 = Accessory detect on MICDET2,

Headphone ground feedback on

HPOUT1FB2

2:0

ACCDET_MODE

[2:0]

000

Accessory Detect Mode Select

000 = Microphone detect (MICDETn,

discrete mode)

001 = Headphone detect (HPDETL)

010 = Headphone detect (HPDETR)

011 = Reserved

100 = Headphone detect (MICDETn)

101 = Reserved

110 = Reserved

111 = Microphone detect (MICDETn,

ADC mode)

Note that the MICDETn measurements

are implemented on either the MICDET1

or MICDET2 pins, depending on the

ACCDET_SRC register bit.

CS47L85 Datasheet(PDF) 234 Page - Cirrus Logic

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