Document Number: 001-06830 Rev. *B Page 4 of 10
Equalizer Operation
The CYV270M0101EQ is an adaptive video cable equalizer
designed to equalize standard definition (SD) serial digital
interface (SDI) video data streams. The CYV270M0101EQ
equalizer is optimized to equalize up to 350m of Canare L-5CFB
and Belden 1694A cable at 270 Mbps. The device contains one
power supply and typically consumes 160 mW power at 3.3V.
The adaptive equalizer meets the SMPTE 259M and DVB-ASI
video standards. It meets all pathological requirements for
SMPTE 259M as defined by RP178. The CYV270M0101EQ
Video Cable Equalizer is auto adaptive from 143 Mbps to 360
Mbps.
The CYV270M0101EQ equalizer has variable gain and multiple
equalization stages that reverse the effects of the cable. This
equalization is achieved by separate regulation of the lower and
higher frequency components in the signal to give a clean output
eye diagram. The CYV270M0101EQ has DC restoration to
compensate the DC content of the SMPTE pathological patterns.
SDI, SDI
The CYV270M0101EQ accepts single-ended or differential
serial video data streams over 75Ω coaxial cable. It is recom-
mended to AC couple the SDI and SDI
inputs as they are inter-
nally biased to 1.2V.
SDO, SDO
The CYV270M0101EQ has differential serial output interface
drivers that use current mode logic [CML] drivers to provide
source matching for the transmission line. These outputs are
either AC coupled or DC coupled to the HOTLink II SerDes
device.
CLI
Cable Length Indicator (CLI) is an analog output that gives an
output voltage proportional to the equalized cable length. CLI
gives an approximation of the length of cable at the differential
serial inputs (SDI, SDI
). CLI works at standard definition (SD)
data rates. The graph in Figure 3 on page 7 illustrates the CLI
output voltage at various Belden 1694A cable lengths. With an
increase in cable length, CLI output voltage decreases.
MCLADJ
Maximum Cable Length Adjust (MCLADJ) sets the approximate
maximum amount of cable to be equalized.
If the MCLADJ voltage is greater than the CLI output voltage, CD
is driven high and the equalizer serial differential outputs (SDO,
SDO
) are muted. If the MCLADJ voltage is less than CLI voltage,
then the equalizer’s differential serial outputs (SDO, SDO
) are
not muted and the incoming data stream is equalized. The graph
in Figure 2 on page 7 illustrates the voltage required at MCLADJ
input to equalize various Belden 1694A cable lengths for SD data
rates. If MCLADJ functionality is not required, this pin should be
left floating or tied to ground to allow maximum equalized cable
length.
CD/MUTE
Carrier Detect/MUTE (CD/MUTE) is a bidirectional pin that
provides an indication of the signal present at the equalizer’s
input, or it controls the muting of the equalizer’s output.
If CD/MUTE is used as an output and the incoming data stream
is not present or the cable length exceeds that set by MCLADJ,
the voltage at the CD/MUTE output is greater than 2.8V. If
CD
/MUTE is used as an output, the incoming data stream is
present and the cable length does not exceed that set by
MCLADJ, then the voltage at the CD/MUTE output is less than
0.8V.
If CD
/MUTE is used as an input, and set LOW, the equalizer
serial outputs are not muted. If the CD
/MUTE is used as an input
and is set HIGH, then the equalizer serial outputs are muted.
When an invalid signal or a signal transmitted with a launch
amplitude of less than 500 mV at SD data rates is received, the
equalizer’s serial outputs are muted and the MCLADJ setting is
overwritten.
BYPASS
The CYV270M0101EQ has a bypass mode that allows the user
to bypass the equalizer’s equalization and DC restoration
functions. When the Bypass mode is tied to V
CC
, the signal
presented at the equalizer’s differential serial inputs (SDI, SDI
)
is routed to the equalizer’s differential serial outputs (SDO, SDO
)
without performing equalization.
When BYPASS is tied to GND, the incoming video data stream
is equalized and presented at the equalizer‘s differential serial
outputs (SDO, SDO
).
In equalizer bypass mode, CD
/MUTE is not functional.
AGC
Place a capacitor of 1 μF between the AGC± pins of the
CYV270M0101EQ equalizer.
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