AK4705 Datasheet, PDF (29/50 Pages) Asahi Kasei Microsystems – 2ch 24bit DAC with AV SCART Switch

[AK4705]
■ RGB Video Gain Control (06H: D1-D0)
VVOL1-0 bits set the RGB video gain.
VVOL1
0
0
1
1
VVOL0
0
1
0
1
Gain
Output level (Typ. @Input=0.7Vpp)
+6dB
1.4Vpp
+7.2dB
+8.2dB
1.6Vpp
1.8Vpp
+9.1dB
2.0Vpp
Table 17. RGB video gain control
(default)
■ Clamp and DC-restore circuit control (06H: D7-D2)
Each CVBS and Y input has the sync tip clamp circuit. The DC-restore circuit has two clamp voltages 0.7V(typ) and
2.2V(typ) to support both RGB and YPbPr signal. They correspond to 0.35V(typ) and 1.1V(typ) at the SCART connector
when matched by 75ohm resistors. The CLAMP1, CLAMP0 and CLAMPB bits select the input circuit for ENCRC pin
(Encoder Red/Chroma), ENCB pin (Encoder Blue), VCRRC pin (VCR Red/Chroma) and VCRB pin (VCR Blue)
respectively. VCLP1-0 bits select the sync source of DC- restore circuit.
CLAMPB
0
0
1
1
CLAMP0
0
1
0
1
VCRRC Input Circuit
VCRB Input Circuit
DC restore clamp active
(0.7V at sync timing/output pin)
Biased
(2.2V at sync timing/output pin)
DC restore clamp active
(2.2V at sync timing/output pin)
DC restore clamp active
(0.7V at sync timing/output pin)
(DC restore clamp active)
(0.7V at sync timing output pin)
DC restore clamp active
(2.2V at sync timing/output pin)
(reserved)
(reserved)
Table 18. DC-restore control for VCR Input
note
for RGB
for Y/C (default)
for Y/Pb/Pr
CLAMPB CLAMP1
0
0
0
1
1
0
1
1
ENCRC Input Circuit
ENCB Input Circuit
DC restore clamp active
(0.7V at sync timing/output pin)
Biased
(2.2V at sync timing/output pin)
DC restore clamp active
(2.2V at sync timing/output pin)
DC restore clamp active
(0.7V at sync timing/output pin)
DC restore clamp active
(0.7V at sync timing output pin)
DC restore clamp active
(2.2V at sync timing/output pin)
(reserved)
(reserved)
Table 19. DC-restore control for Encoder Input
note
for RGB (default)
for Y/C
for
Y/Pb/Pr
CLAMP2
0
1
ENCG Input Circuit
DC restore clamp active
(0.7V at sync timing/output pin)
Sync tip clamp active
(0.7V at sync timing/output pin)
note
for RGB
(default)
for Y/Pb/Pr
Note: When the VTV2-0 bits = “001”(source for TV = Encoder CVBS /RGB), TVG bit = “1” (TVG
= active) and VCLP1-0 bits = “11”(DC restore source = ENCG), the sync tip is selected even
if the CLAMP2 bit = “0”.
Table 20. DC-restore control for Encoder Green/Y Input
MS0451-E-01
- 29 -
2007/06