AK8826 Datasheet, PDF (41/157 Pages) Asahi Kasei Microsystems – HD/SD Multi Format Video Encoder with 3ch DAC

[AK8826VN]
■ Video DAC
The AK8826 has 10-bit resolution, discrete 3 channel current DACs which run at 150MHz.
These DACs are designed to output 1.28Vo-p Full Scale with load resistors of 300-ohm(+/-1.0%) when a
3.9k-ohm(+/-1.0%)resistor is connected between IREF pin and AVSS.
VREF pin should be connected to AVDD via 0.1uF ore more capacitor, and BYPASS pin should be connected to AVSS via
0.1uF or more capacitor. ( Refer to System Connection example. )
Each DAC’s “ON/OFF” can be individually controlled by DACnEN-bit (n=1,2,3) of DAC Control Register [SubAddress0x0D].
At the time of DAC-OFF state, the output DAC is Hi-z.
DAC Control Register
Sub Address 0x0D
bit 7
bit 6
Reserved
Reserved
bit 5
OLVL
bit 4
DTRSTN
bit 3
CVBSSEL
bit 2
DAC3EN
default Value 0x00
bit 1
bit 0
DAC2EN
DAC1EN
The relation between DACnEN-bit (n=1,2,3) and DAC output are shown in following table.
DAC1EN -bit
DAC2EN -bit
DAC3EN -bit
0
1
0
1
0
1
DAC1=OFF
DAC1=ON
DAC2=OFF
DAC2=ON
DAC3=OFF
DAC3=ON
■ DAC Setting
CVBSSEL-bit of DAC Control Register(R/W) [Sub Address 0x0D] sets the output signal from DAC1 and DAC3. Following
table shows the output signal and CVBSEL-bit.
DAC Control Register
Sub Address 0x0D
bit 7
bit 6
Reserved
Reserved
bit 5
OLVL
bit 4
DTRSTN
bit 3
CVBSSEL
bit 2
DAC3EN
default Value 0x00
bit 1
bit 0
DAC2EN
DAC1EN
SD-YC output
SD-CVBS output
HD output
CONVMOD[1:0]=00 CONVMOD[1:0]=00 CONVMOD[1:0]=01
CVBSSEL-bit
0
1
0
DAC1
Y
CVBS
Y
DAC2
C
0-code output
Pb
DAC3
CVBS
0-code output
Pr
ç HD output: Output signal from Component Video Encoder Block
SD-YC output and SD-CVBS output: Output signal from Composite Video Encoder Block
Video DAC mode
CONVMOD[1:0]=10
-
G
B
R
The operation clock of DACs is
Composite Video Encoder mode:
Component Video Encoder mode:
High Speed Video DAC mode:
Same clock-rate as the clock fed into CLKIN-pin.
x2 clock rate of the clock fed into CLKIN-pin
Same clock-rate as the clock fed into CLKIN-pin.
MS0972-E-01
41
2008/12