WM8759

Advanced Information

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AI Rev 3.0 September 2004

16

APPLICATIONS INFORMATION

RECOMMENDED EXTERNAL COMPONENTS

Figure 17 External Component Diagram

In an application where ENABLE is fed directly from VDD rather than a dedicated control line,

resistor R3 and capacitor C9 are used on the ENABLE pin to introduce a short delay in the Low to

High transition of ENABLE. This will ensure the pin goes high after power supplies have had time

to settle (see “ENABLE Operation” in the “Hardware Control Modes” section of the datasheet).

However, if the ENABLE signal is being provided from an external controller chip rather than VDD

directly, R3 and C9 will not be required.

POWER UP/DOWN SEQUENCE

POWER UP/DOWN SEQUENCE

For click free operation, the WM8759 should be powered up and down in a specific sequence.

Power-up:

1.

Power up AVDD and DVDD and wait to settle

2.

Turn on clocks and data (MCLK, BCLK, LRCLK, SDATA)

3.

Switch ENABLE pin from low to high

Power-down:

1.

Switch Enable from high to low

2.

Remove clocks and data

3.

Power down AVDD and DVDD