ak8825 AKM Semiconductor, Inc., ak8825 Datasheet - Page 45

• Manufacturer Part Number: ak8825
• Description: Hd/sd Multi Format Video Encoder With 3ch Dac
• Manufacturer: AKM Semiconductor, Inc.

■ Video DAC
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. )
At the time of DAC-OFF state, the output DAC is Hi-z.
DAC Control Register
Sub Address 0x0D
The relation between DACnEN-bit (n=1,2,3) and DAC output are shown in following table.
■ DAC Setting
table shows the output signal and CVBSEL-bit.
DAC Control Register
Sub Address 0x0D
Rev-E-00
The AK8825 has 10-bit resolution, discrete 3 channel current DACs which run at 150MHz.
Each DAC’s “ON/OFF” can be individually controlled by DACnEN-bit (n=1,2,3) of DAC Control Register [SubAddress0x0D].
CVBSSEL-bit of DAC Control Register(R/W) [Sub Address 0x0D] sets the output signal from DAC1 and DAC3. Following
HD output: Output signal from Component Video Encoder Block
SD-YC output and SD-CVBS output: Output signal from Composite Video Encoder Block
The operation clock of DACs is
Reserved
Reserved
DAC1=OFF
bit 7
bit 7
CVBSSEL-bit
0
DAC1
DAC2
DAC3
Composite Video Encoder mode:
Component Video Encoder mode:
High Speed Video DAC mode:
DAC1EN -bit
Reserved
Reserved
bit 6
bit 6
DAC1=ON
CONVMOD[1:0]=00
SD-YC output
1
CVBS
Y
C
0
OLVL
OLVL
bit 5
bit 5
DAC2=OFF
CONVMOD[1:0]=00
DTRSTN
DTRSTN
SD-CVBS output
0
bit 4
bit 4
0-code output
0-code output
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.
DAC2EN -bit
CVBS
1
45
CVBSSEL
CVBSSEL
DAC2=ON
bit 3
bit 3
1
CONVMOD[1:0]=01
HD output
DAC3EN
DAC3EN
Pb
Pr
Y
0
bit 2
bit 2
DAC3=OFF
0
CONVMOD[1:0]=10
DAC2EN
DAC2EN
DAC3EN -bit
Video DAC mode
bit 1
bit 1
default Value 0x00
default Value 0x00
G
B
R
-
DAC3=ON
DAC1EN
DAC1EN
1
bit 0
bit 0
2008/03
[AK8825]