92hdw74d Integrated Device Technology, 92hdw74d Datasheet - Page 31

• Manufacturer Part Number: 92hdw74d
• Description: 8-channel Hd Audio Codec, Dual Spdif
• Manufacturer: Integrated Device Technology

EIGHT CHANNEL HD AUDIO CODEC, PREMIUM WLP 3/4 COMPLIANT
92HDW74D
EIGHT CHANNEL HD AUDIO CODEC, PREMIUM WLP 3/4 COMPLIANT
the volume in the Volume Knob widget and take appropriate action. Indirect mode is particularly use-
ful when it is undesirable to control all of the DAC amplifier volumes at the same time, or when imple-
menting ADC volume control.
In indirect mode, there are only 128 volume levels in the Volume Knob Cntrl volume bits, the value
will not go beyond the lower and upper limits (0x0 or 0x7F), and an unsolicited response will be gen-
erated if an input event tries to go beyond these limits. Therefore, it is the responsibility of the con-
trolling software to monitor the volume in the Volume Knob Widget and take appropriate action.
Indirect mode is enabled by clearing bit 7 in the Volume Knob Cntrl verb (F0F). The volume is
reflected in the Volume Knob Cntrl bits 6:0 and the step size is 0.75dB. In direct mode, software can
read or write the volume in the Volume Knob widget.
1.4.17.3. Hardware Implementation
The Volume Knob interface is comprised of two input pins, CODEC pins 2 and 4. Both pins have
internal pull-up resistors, so only two push button switches are required for most implementations.
Typically, a series resistor and shunt capacitor are used to help reduce noise and prevent damage
from ESD and other potential faults. An example circuit is shown below in below.
Figure 9: External Volume Control Circuit
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92HDW74D
PC AUDIO
V 1.0 03/08