HMP8156 Intersil Corporation, HMP8156 Datasheet - Page 32

• Manufacturer Part Number: HMP8156
• Description: Ntsc/pal Encoder
• Manufacturer: Intersil Corporation

External Reference Voltage
If an external reference voltage is used, its circuitry should
receive power from the same plane as the HMP8156. The
external VREF must also be stable and well decoupled from
the power plane. An example VREF circuit using a band gap
reference diode is shown in Figure 32.
Evaluation Kits
There
HMP8156EVAL1 is a small daughter card containing the
encoder, voltage references and bypassing, analog output
filters and connectors, a BT.656 interface and connector, and
a 50 pin two row header. The header allows connecting the
pixel and control pins of the encoder into an existing system.
The analog outputs allow the encoder’s performance to be
observed and measured.
are
two
evaluation
75
75
platforms
FIGURE 32. EXTERNAL REFERENCE VOLTAGE CIRCUIT
1.0 H
82pF
ICL8069
FIGURE 33. EXAMPLE POST-FILTER CIRCUITS
6.8K
FIGURE 33A. HIGH QUALITY FILTER
available.
VAA
FIGURE 33B. LOW COST FILTER
560pF
330pF
2.2 H
2.7 H
+
HMP8156
The
4.7 F
32
560pF
330pF
Analog Output Filters
The various video standards specify the freqency response
of the video signal. The HMP8156 uses 2X oversampling
DACs to simplify the reconstruction filter required. Example
post filters are shown in Figure 33. The analog output filters
should be as close as possible to the HMP8156.
The HMP8156EVAL2 is a standard size PC add in card with
an ISA bus interface and application software. The
HMP8156EVAL2 kit is a complete system which allows dem-
onstrating all of the encoder’s operating modes. It has ana-
log video inputs for composite, S-video, and component
RGB signals. The analog signals are converted/decoded to
the digital domain and input to the encoder. The board also
provides a 3 megabyte video RAM for image capture and
display and a BT.656 connector and interface.
0.01 F
1.0 H
39pF
1.235V
RL
RL
75
75