wm8941 Wolfson Microelectronics plc, wm8941 Datasheet - Page 55

• Manufacturer Part Number: wm8941
• Description: Mono Codec With Speaker Driver And Video Buffer
• Manufacturer: Wolfson Microelectronics plc

Production Data
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RECOMMENDED VIDEO BUFFER INITIALISATION SEQUENCE
Power Up (Video signal AC coupled to Video Buffer input):
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Power Up (Video signal DC coupled to Video Buffer input):
1.
2.
3.
4.
5.
6.
7.
Notes:
1. Choose the value of VMIDSEL bits based on the startup time (VMIDSEL = 10 for the slowest
startup, VMIDSEL = 11 for the fastest startup). Startup time is defined by the value of the
VMIDSEL bits (the reference impedance) and the external decoupling capacitor on VMID.
Turn on external power supplies. Wait for supply voltages to settle.
Reset internal registers to default state (software reset).
Set VMIDSEL[1:0] bits for 50kΩ reference string impedance. *Note 1.
Enable bias (BIASEN=1) and Level Shift circuits (LVLSHIFT_EN=1).
Set Video Buffer Gain (VBGAIN) as required.
Set Video Buffer Filter Q Boost (QBOOST) as required.
Enable Video Buffer Clamp (VBCLAMPEN=1).
Enable Video Buffer Pulldown to High Impedance (VBPULLDWN=1).
Enable video buffer (VBUFEN=1).
Wait for 1.5seconds.
Disable Video Buffer Pulldown (VBPULLDWN=0).
Turn on external power supplies. Wait for supply voltages to settle.
Reset internal registers to default state (software reset).
Set VMIDSEL[1:0] bits for 50kΩ reference string impedance. *Note 1.
Enable bias (BIASEN=1) and Level Shift circuits (LVLSHIFT_EN=1).
Set Video Buffer Gain (VBGAIN) as required.
Set Video Buffer Filter Q Boost (QBOOST) as required.
Enable video buffer (VBUFEN=1).
PD, Rev 4.0, August 2008
WM8941
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