SEMICONDUCTOR TECHNICAL DATA
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The MC144144 is a Line 21 closed–caption decoder for use in television
receivers or set–top decoders conforming to the NTSC standard. Capability for
processing and displaying all of the latest standard Line 21 closed–caption
format transmissions is included. The device requires a closed–caption
encoded composite video signal, a horizontal sync signal, and an external
keyer to produce captioned video. RGB and box signal outputs are provided,
which along with the mode select, allow simple interfacing to either color or
black–and–white TV receivers.
Display storage is accomplished with an on–chip RAM. A modified ASCII
character set, which includes several non–English characters, is decoded by an
on–chip ROM. An on–screen character appears as a white or colored dot matrix
on a black background.
Captions (video–related information) can be up to four rows appearing
anywhere on the screen and can be displayed in two modes: roll–up, paint–on,
or pop–on. With rollup captions, the row scrolls up and new information appears
at the bottom row each time a carriage return is received. Pop–on captions work
with two memories. One memory is displayed while the other is used to
accumulate new data. A special command causes the information to be
exchanged in the two memories, thus causing the entire caption to appear at
When text (non–video related information) is displayed, the rows contain a
maximum of 32 characters over a black box which overwrites the screen.
Fifteen rows of characters are displayed in the text mode.
An on–chip processor controls the manipulation of data for storage and
display. Also controlled are the loading, addressing, and clearing of the display
RAM. The processor transfers the data received to the RAM during scan lines
21 through 42. The operation of the display RAM, character ROM, and output
logic circuits are controlled during scan lines 43 through 237. The functions of
the MC144144 are controlled via a serial port which may be configured to be
either I2C or SPI.
Conforms to FCC Report and Order as Amended by the Petition for
Reconsideration on Gen. Doc. 91–1
Conforms to EIA–608 for XDS Data Structure
Supports Four Different Data Channels for Field 1 and Five Different Data
Channels for Field 2, Time Multiplexed within the Line 21 Data Stream:
Captions Utilizing Languages 1 and 2, Text Utilizing Languages 1 and 2
and XDS Support
Output Logic Provides Hardware Underline Control and Italics Slant Generation
Single Supply, Operating Voltage Range: 4.75 to 5.25 V
Supply Current: 20 mA (Preliminary)
Operating Temperature Range: 0 to 70°C
Composite Video Input Range: 0.7 to 1.4 V p–p
Horizontal Input Polarity: Either Positive or Negative
Internal Timing and Sync Signals Derived from On–Chip VCO
In this document, the term ‘user’ refers to the television or VCR designer. The user may choose to make certain optional features selectable by
the viewer. These features then become viewer options.
This document contains information on a new product. Specifications and information herein are subject to change without notice.
Motorola, Inc. 1995