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TB430
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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Copyright © Intersil Americas Inc. 2004. All Rights Reserved. Elantec is a registered trademark of Elantec Semiconductor, Inc.
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EL4583, EL4584, EL4585 Demo Board
Video Sync Separator, Horiz Genlock
EL4583 and EL4584
The EL4583, EL4584, EL4585 demo
board is designed to demonstrate the
operations of Intersil’s family of sync separators and
horizontal genlocks. The board as assembled is designed to
accept NTSC standard video through A4, Video In. The
EL4583 separates H-sync and sends it through jumper R10
to the EL4584. H-sync can be monitored at A1, H-sync. On
the board settings, the internal divider mode is selected and
the divider N is set to 910. The EL4584 uses its internal
divider to extract a clock pulse of the same H-sync input
frequency from the oscillator and adjusts the on-board LC
VCO to phase lock this signal to the input horizontal
frequency. This divided clock signal can be monitored at A2,
EXT DIV. The full clock frequency (which should equal to
H-sync (15.734kHz)*divider (910) = 14.318MHz) is available
at A3, CLK OUT. Each board has been tested with a NTSC
signal and C17 adjusted so EXT DIV locks to the H-sync.
SW1 has 3 positions. LEFT grounds COAST and puts the
EL4584 into normal mode (see data sheet for mode
descriptions). CENTER floats COAST and is fast lock mode,
and RIGHT pulls COAST to VDD and is coast mode. The
signal should lock in normal mode. The DIP switches at the
top of the board works as follows: from right to left, the
switches should be labeled 1, 2, 3, 4. Dip-SW4 controls pin
B, SW3 controls C, SW2 controls A, and SW1 controls DIV
SEL pin 7 on the EL4584. Refer to the data sheet for a table
of divisors for each switch setting and the operation of DIV
SEL. If using a NTSC signal, setting all switches ON will
produce a CLK OUT frequency of 14.318MHz, and an EXT
DIV frequency of 15.734kHz, and the EL4584 will lock.
To convert the oscillator to work with the standard PAL
frequency of 17.734MHz, simply substitute an inductor of
about 8.2µH to bring the center frequency up closer to PAL
frequency of 17.734MHz, and reset the dip switches to
A = 0, B = 1, C = 1. Remember that LC VCOs have a wide
pull range so they are very tolerant of component variations.
In some cases the 10µH inductor may be able to produce
the necessary PAL frequency as well as the NTSC
frequency.
Crystal VCXOs and 4-pin VCXO hybrids can also be used.
See the accompanying schematics and data sheet for more
info.
EL4585
An EL4585 can be used in place of the EL4584 provided.
With R1 changed to 3.3µH and the same settings as in the
EL4584 section, The signal frequency at CLK OUT is
28.636MHz.
Technical Brief February 24, 2004
