WM8961
Pre-Production
If a volume update is attempted while the signal is a non-zero value, an audible click could occur as
shown in Figure 24.
Figure 24 Click Noise during Volume Update
In order to prevent this click noise, a zero cross function is provided. When enabled, this will cause the
PGA volume to update only when a zero crossing occurs, minimising click noise as shown in Figure
25.
Figure 25 volume Update using Zero Cross Detection
If there is a long period where no zero-crossing occurs, a timeout circuit in the WM8961 will
automatically update the volume. The volume updates will occur between one and two timeout
periods, depending on when the volume update bit is set as shown in Figure 26. The TOEN register
bit must be set to enable this timeout function. The timeout period is set by CLK_TO_DIV[1:0].
PP, August 2009, Rev 3.1
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
