WM8731 datasheet(28/56 Pages) WOLFSON

Part #	WM8731

Description	Portable Internet Audion CODEC with Headphone Driver and Programmable Sample Rates

PDF	56 Pages

Scroll/Zoom	100%

Manufacturer	WOLFSON [Wolfson Microelectronics plc]

Direct Link	http://www.wolfsonmicro.com

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28 / 56 page

WM8731

Advanced Information

WOLFSON MICROELECTRONICS LTD

AI Rev 2.0 February 2001

The recommended external components required to complete the application are shown in Figure 21.

AGND

HPOUT

Figure 21 Headphone Output Application Drawing

Recommended values are C1 = 220uF (10V electrolytic), R1 = 47k

C1 forms a DC blocking capacitor to isolate the dc of the HPOUT from the headphones. R1 form a

pull down resistor to discharge C1 to prevent the voltage at the connection to the headphones from

rising to a level that may damage the headphones.

BYPASS MODE

The WM8731 includes a bypass mode whereby analogue line inputs are routed directly to the

analogue line outputs and headphone outputs. The scheme for this is in Figure 22.

12.5K

VMID

LINEIN

VMID

HPOUT

VMID

FROM

LINE

INPUTS

LINEOUT

FROM

DAC

BYPASS (ON)

DACSEL (OFF)

SIDETONE (OFF)

Figure 22 Signal Routing in Bypass Mode

WM8731 Datasheet(PDF) 28 Page - Wolfson Microelectronics plc