WM8255 datasheet(37/49 Pages) CIRRUS

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WM8255

Production Data

PD, Rev 4.7, August 2013

POWER ON SEQUENCE

In order to guarantee correct operation, the digital supply (DVDD) and analogue supply (AVDD1)

should be applied as specified in Figure 29 and Table 5.

If it is not possible to apply the recommended power up sequence, the user must wait until both

DVDD and AVDD1 have risen fully, then disable and enable the WM8255 by software write to EN

(R0, b0). It is then possible to apply further register writes and operate the WM8255 correctly.

When powering down the WM8255, no specific power down sequence is required.

REDUCED POWER

With DVDD applied, AVDD1 may be powered down with no loss to digital configuration data. This will

reduce the power consumption of the device whilst still keeping register settings and configurations.

Figure 29 Power On Sequence

Test Conditions

AVDD1 = 5.75V, DVDD = 3.3V, AGND = DGND = AVDD2 = 0V, TA = 25C, MCLK = 24MHz unless otherwise stated.

PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNITS

DVDD set up time to AVDD1 rising

edge

tPSU

100

μs

Table 5 Power On Timing

OPERATING MODES

Table 6 summarises the most commonly used modes, the clock waveforms required and the register

contents required for CDS and non-CDS operation.

MODE

DESCRIPTION

CDS

AVAILABLE

MAX

SAMPLE

RATE

TIMING

REQUIREMENTS

CONTENTS WITH

CDS

CONTENTS

WITHOUT CDS

Monochrome/

Colour Line-by-Line

Yes

6 MSPS

MCLK max = 24MHz

MCLK:VSMP ratio is

2n:1 n

 2

SetReg1: 0F(hex)

SetReg1: 0D(hex)

Fast Monochrome/

Colour Line-by-Line

Yes

8 MSPS

MCLK max = 24MHz

MCLK:VSMP ratio is

3:1

Identical to Mode

1 plus SetReg3:

bits 5:4 must be

set to 0(hex)

Identical to

Mode 1

Maximum speed

Monochrome/

Colour Line-by-Line

12 MSPS

MCLK max = 24MHz

MCLK:VSMP ratio is

2:1

CDS not possible

SetReg1: 4D(hex)

Table 6 WM8255 Operating Modes

*Note: Maximum sample rate depends on the MCLK to VSMP ratio. A higher ratio will mean a lower

maximum sample rate for a specified MCLK speed.

WM8255 Datasheet(PDF) 37 Page - Cirrus Logic

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