Intel® 820E Chipset

R

88 Design Guide

Figure 52. CDC_DN_ENAB# Support Circuitry for Multi-Channel Audio Upgrade

Primary
Audio
Codec
RESET#
SDATA_IN
Audio
Codec
RESET#
ID0#
SDATA_IN
AC97_RESET#
CDC_DN_ENAB#
CNR BoardMotherboard
RA
10 k
To General
Purpose Input
From AC '97
Controller
CNR Connector
SDATA_IN0
SDATA_IN1
To AC '97
Digital
Controller
Vcc
RB
100 k

Figure 52 shows the circuitry required on the motherboard to support a two-codec down configuration.

This circuitry disables the codec on a single codec CNR. Notice that in this configuration the resistor,

RB, has been changed to 100 k.

Figure 53. CDC_DN_ENAB# Support Circuitry for Two-Codecs on Motherboard / One-Codec on

CNR

Primary
Audio
Codec
RESET#
SDATA_IN
Audio
Codec
RESET#
ID0#
SDATA_IN
AC97_RESET#
CDC_DN_ENAB#

CNR BoardMotherboard

RA
10 k
To General
Purpose Input
From AC '97
Controller

CNR Connector

SDATA_IN0
SDATA_IN1
To AC '97
Digital
Controller
Secondary
Codec
RESET#
SDATA_IN
Vcc
RB
100 k

Figure 53 shows the case of two-codecs down and a dual-codec CNR. In this case, both codecs on the

motherboard are disabled (while both on CNR are active) by RA being 10 k and RB being 1 k.