HMP8156ACN Intersil, HMP8156ACN Datasheet - Page 3

• Manufacturer Part Number: HMP8156ACN
• Description: NTSC/PAL Encoder 64-Pin MQFP
• Manufacturer: Intersil

Specifications of HMP8156ACN

• Package: 64MQFP
• Operating Temperature: 0 to 70 °C

Functional Operation
The HMP8154 and HMP8156A are fully integrated digital
encoders. Either accepts digital video input data and
generates four analog video output signals. The input data
format is selectable and includes YCbCr, RGB, and overlay
data. The outputs are configurable to be either two
composite video signals and Y/C (S-Video) or one
composite and component RGB video.
The HMP8154/HMP8156A accepts pixel data in one of
several formats and transforms it into 4:4:4 sampled
luminance and chrominance (YCbCr) data. If enabled, the
encoder also mixes overlay data with the input data. The
encoder then interpolates the YCbCr data to twice the pixel
rate and low pass filters it to match the bandwidth of the
video output format. If enabled, the encoder also adds
Closed Captioning information to the Y data. At the same
time, the encoder modulates the chrominance data with a
digitally synthesized subcarrier. Finally, the encoder outputs
luminance, chrominance, and their sum as analog signals
using 10-bit D/A converters.
The HMP8154/HMP8156A provides operating modes to
support all versions of the NTSC and PAL standards and
accepts full and SIF size input data with rectangular (ITU-R
BT.601) and square pixel aspect ratios. It operates from a
single clock at twice the pixel clock rate determined by the
operating mode.
The HMP8154/HMP8156A’s video timing control is flexible. It
may operate as the master generating the system’s video
timing control signals or it may accept external timing
controls. The polarity of the timing controls and the number
of active pixels and lines are programmable.
The HMP8154 provides optional vertical flicker reduction.
When enabled, the encoder passes the pixel data after
overlay processing through a three line flicker filter.
Pixel Data Input Formats
The HMP8154 accepts pixel data via the P0-P23 input pins.
The definition of each pixel input pin is determined by the
input format selected in the input format register. The
definition for each mode is shown in Table 1.
YCbCr Pixel Data
The HMP8154/HMP8156A accepts 4:2:2 sampled YCbCr
input data. The luminance and color difference signals are
each 8 bits, scaled 0 to 255. The nominal range for Y is 16
(black) to 235 (white). Y values less than 16 are clamped to
16; values greater than 235 are processed normally. The
nominal range for Cb and Cr is 16 to 240 with 128
representing zero. Cb and Cr values outside their nominal
range are processed normally. Note that when converted to
the analog outputs, some combinations of YCbCr outside their
nominal ranges would generate a composite video signal
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HMP8154, HMP8156A
larger than the analog output limit. The composite signal will
be clipped but the S-video outputs (Y and C) will not be.
The color difference signals are time multiplexed into one
8-bit bus beginning with a Cb sample. The Y and CbCr
busses may be input in parallel (16-bit mode) or may be time
multiplexed and input as a single bus (8-bit mode). The
single bus may also contain SAV and EAV video timing
reference codes (BT.656 mode).
RGB Data
The HMP8154/HMP8156A accepts 4:4:4 sampled RGB
component video input data. The color signals may be
(8,8,8) for 24-bit mode or (5,6,5) for 16-bit mode. In 24-bit
mode, they are scaled 0 to 255, black to white. In 16-bit
mode, the encoder left shifts the input so that it has the same
scale as 24-bit input. The RGB data may be linear or gamma
corrected; if enabled, the encoder will gamma correct the
input data.
Overlay Data
The HMP8154/HMP8156A accepts 5 bits of pixel overlay
input data and combines it with the input pixel data. The data
specifies an overlay color and the fractions of the new and
original colors to be summed.
Blue Screen Generation
In blue screen mode, the HMP8154/HMP8156A ignores the
pixel input data and generates a solid, blue screen. The
overlay inputs may be used to place information over the
blue screen.
Input Processing
Color Space Conversion
For linear RGB input formats, the encoder applies gamma-
correction using a selectable gamma value of 1/2.2 or 1/2.8.
The gamma-corrected RGB data from either the correction
function in linear mode or the input port otherwise is
converted to 4:4:4 sampled YCbCr data.
For the YCbCr input formats, the encoder converts the 4:2:2
sampled data to 4:4:4 sampled data. The conversion is done
by 2x upsampling the Cb and Cr data. The upsampling
function uses linear interpolation.
Overlay Processing
The HMP8154/HMP8156A accepts overlay data via the
OL0-OL2, M0, and M1 pins. Overlay mixing is done using
the 4:4:4 YCbCr pixel data from the color space converter.
The YCbCr data following overlay processing is used as
input data by the video processing functions.
The OL0-OL2 inputs select the color to be mixed with the
pixel data. Overlay colors 1-7 are standard color bar colors.
Overlay color 0 is special and disables mixing on a pixel-by-
pixel basis. The overlay color palette is shown in Table 2.
August 20, 2009
FN4343.5