CS3318 Datasheet, PDF (19/44 Pages) Cirrus Logic – 8-Channel Analog Volume Control

CS3318
5.5 Volume Controls
The CS3318 provides comprehensive volume control functionality, allowing each channel’s volume to be
changed on an individual or master basis. Refer to the “Volume & Muting Control Architecture” section on
page 17 for complete details about the configuration of the CS3318’s individual and master controls.
The CS3318 incorporates zero-crossing detection capabilities, and all volume changes are implemented as
dictated by the zero-crossing detection settings (see “Zero-Crossing Detection” on page 22).
5.5.1
Individual Channel Volume Controls
The CS3318 provides 8 individual channel volume controls. These controls can be used to independently
gain and/or attenuate each of the input/output channels over a range of +22 dB to -96 dB in ¼ dB steps.
Each channel has a corresponding Ch. X Volume register used to gain or attenuate the channel from
+22 dB to -96 dB in ½ dB steps. The ¼ dB Control register contains one bit per channel used to add an
additional ¼ dB gain to the channel’s volume as set by its Ch. X Volume register.
Referenced Control
Register Location
Ch. X Volume ...................... “Ch 1-8 Volume - Addresses 01h - 08h” on page 31
¼ dB Control ....................... “¼ dB Control - Address 09h” on page 32
5.5.2
Master Volume Controls
The CS3318 master volume controls allow the user to simultaneously gain or attenuate a user defined set
of channels from +22 dB to -96 dB in ¼ dB increments. A total of 3 master volume controls, Master 1,
Master 2, and Master 3, are provided for comprehensive and flexible control.
Each master volume control has a corresponding Master X Volume register which is used to gain or at-
tenuate the control’s respective unmasked channels from +22 dB to -96 dB in ½ dB steps. The LSB of the
corresponding Master X Control register contains one bit used to add an additional ¼ dB gain to the mas-
ter volume control’s value as set by its Master X Volume register.
As discussed in the “Volume & Muting Control Architecture” section on page 17, each master volume con-
trol has a corresponding Master X Mask register which allows the user to select which channels are af-
fected by the control. By default, each master control is configured to affect all channels within the device.
The effective volume setting of an individual channel is determined by the following equation:
EffVol_ChN = Individual_ChN + (Master 1 & Mask 1_ChN) + (Master 2 & Mask 2_ChN) + (Master 3 & Mask 3_ChN)
Equation 1. Effective Volume Setting
In this equation, EffVol_ChN represents the actual gain or attenuation level, in dB, of the individual channel
“N” as determined by the its constituent volume settings within the CS3318. The effective volume is limited
to the range of +22 dB to -96 dB; see “Volume Limits” on page 20.
Individual_ChN is the individual channel volume setting in dB as set by the channel’s individual volume con-
trol register and ¼ dB bit (see “Individual Channel Volume Controls” on page 19).
Master X is the Master X volume setting in dB as set by the master volume control registers and their re-
spective ¼ dB bits.
Mask X_ChN is the channel N mask bit associated with the Master X volume control setting.
This volume control architecture in combination with the multiple group addressing capabilities of the
CS3318 (as detailed in section 5.8.2 on page 24) allows easy volume control of multiple channels across
multiple devices in a system while eliminating the system controller overhead typically associated digitally
driven analog volume control devices.
DS693F1
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