
ASAHI KASEI 
[AK4706] 
MS0507-E-00 
2006/05 
- 21 - 
 System Reset and Full Power-down Mode 
The AK4706 should be reset once by bringing PDN pin = “L” upon power-up. 
 PDN pin: Power down pin 
“H”:  Normal operation 
“L”:  Device power down. 
 Auto Startup Mode 
When the PDN pin is set to “H”, the AK4706 is in the auto startup mode. In this mode, all blocks except for the video 
detection circuit are powered down. Once the video detection circuit detects video signal from TVVIN pin or VCRVIN 
pin, the AK4706 goes to the stand-by mode (Both Fast Blanking and Slow Blanking are also fixed to VCR-TV 
Loop-through) automatically and sends “H” pulse via INT pin. To exit the auto startup mode, set the AUTO bit to “0”.  
The HD video outputs in the auto startup mode are disable at power-up.  In this mode, HD video outputs are controlled as 
shown in Table 3. 
 AUTO bit (00H D3): Auto startup bit (SD Video output) 
“1”:  Auto startup enable (default). 
“0”: Auto startup disable (Manual startup). 
HDAPW bit (0AH D5): Auto startup bit (HD Video output) 
“1”:  Auto startup enable. 
“0”:  Auto startup disable (Manual startup: default). 
AUTO bit 
HDAPW bit 
0 
0 
0 
1 
1 
0 
1 
1 
HD Video output 
Set by HDSW1/0, HDCP1/0 bit 
Hi-Z 
Hi-Z 
Set by HDSW1/0, HDCP1/0 bit  
after a video signal is detected. 
Table 3. HD Video output status 
The Figure 2 shows an example of the system timing at auto startup mode. 
PDN pin 
Low Power Mode 
Auto startup enable 
Audio out (DC)
don’t care 
Clock, Data in
TVVOUT, 
VCRVOUT
Active (loop-through)
TVVIN
Signal in  
No Signal 
don’t care
Signal in  
No Signal 
don’t care
VCRVIN
Signal in  
No Signal 
don’t care
don’t care
Active (loop-through) 
Hi-Z 
Hi-Z 
Active (loop-through)  
(GND) 
Active (loop-through) 
No Signal 
No Signal 
Hi-Z 
Low Power Mode
Low Power Mode 
HD Video
OUTPUT
Active   
Hi-Z 
Hi-Z 
Active   
Hi-Z 
“0” (default)
HDAPW bit
“1” 
AUTO bit
“1”(defaoult) 
Figure 2.Auto startup mode sequence