WM8946ECSSLASHR datasheet(89/175 Pages) WOLFSON

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Production Data

WM8946

PD, July 2012, Rev 4.3

Power Up (Video signal DC coupled to Video Buffer input):

ACTION

LABEL

Turn on external supplies and wait for the

supply voltages to settle.

Reset registers to default state (software

reset)

SW_RESET

R0 (00h) [15:0]

Enable VMID Fast Start and Start up

Bias

Select Start-Up Bias and set VMID soft

start for start-up ramp

VMID_FAST_START = 1

STARTUP_BIAS_ENA = 1

BIAS_SRC = 1

VMID_RAMP[1:0] = 01

R7 (07h) [11]

R7 (07h) [8]

R7 (07h) [7]

R7 (07h) [6:5]

If using VMID as the reference voltage

for the LDO then select VMID fast start or

set to 0 if using the Bandgap as the

reference voltage for LDO.

Select LDO Start-Up Bias and enable

LDO

Delay 300ms for LDO to settle

LDO_REF_SEL_FAST = 1

LDO_BIAS_SRC = 1

LDO_ENA = 1

R53 (35h) [14]

R53 (35h) [5]

R53 (35h) [15]

Enable VMID Buffer and Master Bias

Set VMID_SEL[1:0] for fast start-up

BIAS_ENA = 1

VMID_BUF_ENA = 1

VMID_SEL[1:0] = 11

R2 (02h) [3]

R2 (02h) [2]

R2 (02h) [1:0]

Enable VMID

Delay 150ms to allow VMID to settle

VMID_ENA = 1

R7 (07h) [4]

Set LDO for normal operation

LDO_REF_SEL_FAST = 0

LDO_BIAS_SRC = 0

R53 (35h) [14]

R53 (35h) [5]

Set VMID for normal operation

VMID_FAST_START = 0

STARTUP_BIAS_ENA = 0

R7 (07h) [11]

R7 (07h) [8]

Set VMID divider for normal operation

VMID_SEL = 01

R2 (02h) [1:0]

Set Video Buffer Gain as required

VB_GAIN

R38 (26h) [5]

Set Video Buffer Filter Q Boost as

required

VB_QBOOST

R38 (26h) [6]

Enable video buffer

VB_ENA = 1

R38 (26h) [7]

WM8946ECS/R Datasheet(PDF) 89 Page - Wolfson Microelectronics plc

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