WM8956 datasheet(24/80 Pages) WOLFSON

Part #	WM8956

Description	Hi-Fi DAC with 1W Stereo Class D Speaker Drivers and Headphone Drivers

PDF	80 Pages

Scroll/Zoom	100%

Manufacturer	WOLFSON [Wolfson Microelectronics plc]

Direct Link	http://www.wolfsonmicro.com

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24 / 80 page

WM8956

Preliminary Technical Data

PTD, July 2007, Rev 2.1

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 register 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 10. 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.

Figure 10 Microphone Bias Schematic

WM8956 Datasheet(PDF) 24 Page - Wolfson Microelectronics plc