- SS-HQ1 Application Notes -
Ver.1.0.0 January 7, 2005
29
3.9.3. Circuit Configuration for Composite Output
When composite output is used (DACMODE=0[h]), the Y/Composite signals are mixed inside the CXD3172AR
and output through the IOY pin (pin 75). With this configuration, the IOC pin (pin 67) is not used.
illustrates an example circuit for composite output.
Note that with composite output, it is not possible to completely remove the digital components of the
sub-carrier signal because a BPF is not connected.
The signal level output from the IOY pin changes depending on the setting for the voltage being input to the
VREFY pin. Input and adjust the voltage as appropriate.
Note that the voltage input to the VREFY pin must be in the range of 0.6 to 1.1V based on the specifications
for the CXD3172AR’s internal DAC. Therefore, use a configuration in which an amplifier circuit is placed in the
final stage. Note that proper operations cannot be guaranteed if the voltage is input using any other type of
configuration.
Fig 3.9-2 Example Circuit for Composite Output
CXD3172AR
3.3V
69
VGC
AVD6
74
3.3V
IRE
F
C
70
AVS
6
65
IOY
75
220
0.1u
VIDEO AMP
IREFY
71
3.3k
VGY
72
0.1u
3.3V
VREFY
73
Voltage is inputted.
VREFC
68
IO
C
67