WM8972LEFLSLASHR datasheet(35/49 Pages) WOLFSON

35 / 49 page

Preliminary Technical Data

WM8972L

PTD Rev 2.2 June 2004

The WM8972L has two possible device addresses, which can be selected using the CSB pin.

CSB STATE

DEVICE ADDRESS

Low

0011010 (0 x 34h)

High

0011011 (0 x 36h)

Table 31 2-Wire MPU Interface Address Selection

POWER SUPPLIES

The WM8972L can use up to four separate power supplies:

•

AVDD / AGND: Analogue supply, powers all analogue functions except the headphone drivers.

AVDD can range from 1.8V to 3.6V and has the most significant impact on overall power

consumption (except for power consumed in the headphone). A large AVDD slightly improves

audio quality.

•

OPVDD / OPGND: Output supply, powers the output drivers. OPVDD can range from 1.8V to

3.6V. OPVDD is normally tied to AVDD, but it requires separate layout and decoupling

capacitors to curb harmonic distortion. With a larger OPVDD, louder speaker outputs can be

achieved with lower distortion. If OPVDD is lower than AVDD, the output signal may be clipped.

•

DCVDD: Digital core supply, powers all digital functions except the audio and control

interfaces. DCVDD can range from 1.42V to 3.6V, and has no effect on audio quality. The

return path for DCVDD is DGND, which is shared with DBVDD.

•

DBVDD: Digital buffer supply, powers the audio and control interface buffers. This makes it

possible to run the digital core at very low voltages, saving power, while interfacing to other

digital devices using a higher voltage. DBVDD draws much less power than DCVDD, and has

no effect on audio quality. DBVDD can range from 1.8V to 3.6V. The return path for DBVDD is

DGND, which is shared with DCVDD.

It is possible to use the same supply voltage on all four. However, digital and analogue supplies

should be routed and decoupled separately to keep digital switching noise out of the analogue signal

paths.

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