AK8855 Datasheet, PDF (62/81 Pages) Asahi Kasei Microsystems – NTSC/PAL Digital Video Decoder

[ASAHI KASEI]
AK8855
At No Input Signal Condition
Two output modes can be selected when no Video signal is input to the AK8855.
Default value is Black code output. Setting is made by NSIGMD-bit of Output Control 2 Register ( R/W ) [ Sub
Address 0x02 ].
Detection of no signal condition is notified by a hardware pin and Status Register ( R / W ) [ Sub Address
0x10 ].
[ NSIGMD ]-bit
This is a control bit to set output signal processing when no signal is input.
[NSIGMD]-bit
Output signal when no signal is input
0
Black code output
1
Input signal is directly output as is.
Condition
Y = 0x10
Cb/Cr = 0x80
So-called “ Sand-Storm “ mode
output.
Power-Down Mode
The AK8855 has a power-saving wait mode function.
PDN pin is used to put the AK8855 into power-saving mode, including digital block. By setting this pin to low, all
blocks in Analog and Digital parts are put into power-saving mode.
Recover from the power-saving mode by PDN pin , a Reset sequence must be executed.
When to turn down power supplies except for PVDD, a power-down sequence must be followed, using PDN pin
and then turn-down AVDD /DVDD after power-down condition is established.
It is recommended to fix the digital output pins to PVDD power supply or to set OE pin = high ( high output ).
Output Pin Condition
Output pins of the AK8855 are controlled by OE ( Output Enable ) pin and RSTN pin conditions.
Output pin conditions are :
After Power
up
RSTN = Low
After Reset sequence
PDN = Low PDN = High
OE = High unknown
Hi-z
High
Data output
OE = Low
Hi-z
Hi-z
Hi-z
Hi-z
Note ) there is a possibility that leak current may flow at OE = Low ( Hi-Z condition ).
It is recommended that output pins are set to same PVDD potential or OE pin is set to High in Power-Down
mode setting.
Pins to be controlled by OE pin are, CLKO, D [ 7 : 0 ], FIELD, HD / HV, VD / VAF, NSIG and DVALID pins.
MS0319-E-03
62
2004 / 11