LMH0324
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ZHCSIC8B –APRIL 2016–REVISED JUNE 2018
VOD
VODDE
Figure 8. VOD and VODDE Levels
7.3.8 Additional Programmability
The LMH0324 supports extended programmability through the use of an SPI or SMBus serial control interface.
Such added programmability includes:
•
•
Cable Length Indicator (CLI).
Digital MUTEREF
7.3.8.1 Cable Length Indicator (CLI)
The Cable Length Indicator (CLI) indicates the length of the coaxial cable attached to IN0+. CLI is accessible
through CableEQ/Driver Page Reg 0x25[5:0]. The 6-bit setting ranges in decimal value from 0 to 55 (000000'b to
110111'b binary), corresponding to approximately 0 to 600 m of Belden 1694A cable.
7.3.8.2 Digital MUTEREF
Digital MUTEREF CableEQ/Driver Page Reg 0x03[5:0] sets the threshold for the maximum cable length to be
equalized before muting the outputs. The MUTEREF register value is directly proportional to the cable length
being equalized. MUTEREF is data rate dependent. Follow the steps below to set MUTEREF register setting for
any desired SDI rate:
1. Connect the desired input cable length at which the driver output needs to be muted.
2. Send video pattern at IN0+ at the SD rate (270 Mbps). At SD, the Cable Length Indicator (CLI) has the
largest dynamic range.
3. Read back Cable EQ/Driver Page Reg 0x25[5:0] to record the CLI value.
4. Copy the CLI value, and write this value to Digital MUTEREF Cable EQ/Driver Page Reg 0x03[5:0].
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