WM8960CGEFLSLASHV datasheet(26/94 Pages) CIRRUS

26 / 94 page

WM8960

Rev 4.4

MICROPHONE BIASING CIRCUIT

The MICBIAS output provides a low noise reference voltage suitable for biasing electret type

microphones and the associated external resistor biasing network. Refer to the

“Applications

Information

” section for recommended external components. The MICBIAS voltage can be altered via

the

MBSEL

bit.

When

MBSEL=0,

MICBIAS=0.9*AVDD

and

when

MBSEL=1,

MICBIAS=0.65*AVDD. The output can be enabled or disabled using the MICB control bit.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R25 (19h)

Power

management (1)

MICB

Microphone Bias Enable

0 = OFF (high impedance output)

1 = ON

R48 (30h)

Additional Control

(4)

MBSEL

Microphone Bias Voltage Control

0 = 0.9 * AVDD

1 = 0.65 * AVDD

Table 7 Microphone Bias Control

The internal MICBIAS circuitry is shown in Figure 9. The maximum source current capability for

MICBIAS is 3mA. The external biasing resistors therefore must be large enough to limit the MICBIAS

current to 3mA.

AGND

MBVSEL=0

MICBIAS

= 1.8 x VMID

= 0.9 X AVDD

VMID

internal

resistor

internal

resistor

MBVSEL=1

MICBIAS

= 1.3 x VMID

= 0.65 X AVDD

Figure 9 Microphone Bias Schematic

WM8960CGEFL/V Datasheet(PDF) 26 Page - Cirrus Logic

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