AK8813 Datasheet, PDF (19/51 Pages) Asahi Kasei Microsystems – NTSC/PAL Digital Video Encoder

ASAHIKASEI
[AK8813/14]
♦ Color burst signal
Color burst signal is generated by 32bits-length Digital Frequency Synthesizer. The Default frequency of
the color burst is selected by [Video Process 1 Register(0x01)].
Standard
NTSC-M
PAL-M
PAL-B,D,G,H,I
PAL-N(Arg.)
PAL-N(non-Arg.)
PAL60
NTSC-4.43
Sub-carrier Freq.
[MHz]
3.57954545
Video Process
1
[VM1,VM0]
[0,0]
3.57561188
[0,1]
4.43361875
[1,1]
3.5820558
[1,0]
4.43361875
[1,1]
4.43361875
[1,1]
4.43361875
[1,1]
Burst Signal Table
Sub-carrier frequency 3.57561188MHz is allowed when PAL-M mode is selected.
The burst frequency and initial phase resolution are as follows.
Frequency resolution
SCH Phase resolution
0.8046Hz
360°/256
♦ Video DAC
AK8813/14 has the three current driven 10bits-DACs at 27MHz operation. The full scale voltage of DAC
is determined by the current output from IREF pin. Typical output voltage is 1.28Vo-p under the condition
of VREFIN 1.235V, 6.8KΩ between IREF pin and Ground(AVSS) and DAC load resistance of 220Ω. This
full-scale voltage should be set in the range of 1.17V to 1.33V by adjusting the resistor which terminates
IREF pin. Each DAC output can be set to “active state” or to “inactive state” individually by [DAC Mode
register(05H)]. When DAC is in “inactive state”, the output is Hi-impedance. When all DACs are set to
“inactive state”, the analog part of AK8813/14 goes into sleep mode. In this case AK8813/14 stops
outputting the reference voltage(VREF) output. When any DAC is switched over in “active state” from sleep
mode, AK8813/14 starts outputting reference voltage. In this case AK8813/14 needs several milliseconds
for VREF wake-up time.
Using internal VREF as the reference voltage, connect [VREF OUT] pin with [VREF IN] pin and [VREF
OUT] pin is terminated with more than 0.1uF capacitor.
♦ Use external Reference Voltage
In order to improve the accuracy of DAC output, external reference voltage may be used. In this case,
VREFOUT pin still needs to be terminated with more than 0.1uF capacitor.
Rev.00
- 20 -
2004/Oct