LMH1983 Evaluation Kit Users Guide
Page 10 of 25
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625i/25
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625p/50
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720p/23.98/24/25/29.97/30/50/59.94/60
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1080i/25/29.97/30
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1080p/23.98/24/25/29.97/30/50/59.94/60
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1080pSf/23.98/24/25/29.97/30
Audio Word Clock
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32 kHz, 48 kHz, 96 kHz, 44.1 kHz
System Clock
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27 MHz
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10 MHz
Configuring the board for operation with a digital video
reference signal
An external digital reference signal, consisting of H,V and F may be applied to J2, a
jumper should installed on JP5, and the jumper on JP3 should be removed.
The GUI will display what format is being detected under the PLL1
For a comprehensive list of formats that can be detected, please refer to the LMH1983
datasheet. To determine format, the device measures the period of the Hsync input by
counting 27MHz clock pulses over several Hsync periods. There are some standards
where Hsync may be the same, in which case V and F are examined to determine if the
reference is an interlaced or progressive format before format detection is complete.
Configuring the board for operation in free-run mode, using
the on board reference oscillator
To operate the board in ‘stand-alone mode’, remove the jumper for JP3, make sure that
the jumper is removed from JP5, and in this mode, the frequency can be trimmed via R20
– the trim pot near the lower left corner of the board.
Configuring the board for operation, locked to an external
clock oscillator.
To operate the board locked to an external clock, supply the reference signal through the
SMA connector ‘J3’, remove the jumper form JP3 and install a jumper on JP5.
The automatic format detect algorithm in the LMH1983 will recognize reference clocks
of 27MHz or 10MHz. Other reference rates can be manually programmed.
