Datasheet

SDO
SDO
0-30" FR4 Trace
LMH0356
SDI0
SDI0
LMH0344
3G/HD/SD
SDI Cable Equalizer
Coaxial Cable
75:
37.4:
75:
3.9 nH
1.0 PF
1.0 PF
SDI
SDI
LMH0356
SNLS270K –AUGUST 2007–REVISED APRIL 2013 www.ti.com
The SD/HD output may be used to drive the SD/HD pin of an SDI cable driver (such as the LMH0302) in order to
properly set the cable driver’s edge rate for SMPTE compliance. It defaults to HD/3G (low) when the LMH0356 is
not locked.
SCO_EN has an internal pulldown to set the second output (SCO/SDO2) to output data. This pin may be pulled
high to set the second output as a serial clock.
The external loop filter capacitor (between LF1 and LF2) should be 56 nF. This is the only supported value; the
loop filter capacitor should not be changed.
RATE0 and RATE1 have internal pulldowns to select Auto-Rate Detect mode by default. These pins may also be
used to set the device to SD mode or HD/3G mode.
SEL0 and SEL1 have internal pulldowns to select the SDI0 input by default.
The inputs are LVPECL compatible. The LMH0356 has a wide input common mode range and in most cases the
input should be DC coupled. For DC coupling, the inputs must be kept within the common mode range specified
in DC Electrical Characteristics.
Figure 7 shows an example of a DC coupled interface between the LMH0344 cable equalizer and the LMH0356.
The LMH0344 output common mode voltage and voltage swing are within the range of the input common mode
voltage and voltage swing of the LMH0356. In this figure, the LMH0344 cable equalizer restores the signal after
the coaxial cable. The LMH0356 FR4 equalizer restores the signal after the loss due to the FR4 trace. The
LMH0356 inputs have 50Ω internal terminations (100Ω differential) to terminate the transmission line, so no
additional components are required.
The outputs are LVPECL compatible. SDO is the primary data output and SCO/SDO2 is a second output that
may be set as the serial clock or a second data output. Both outputs are always active. The LMH0356 output
should be DC coupled to the input of the receiving device as long as the common mode ranges of both devices
are compatible.
Figure 8 shows an example of a DC coupled interface between the LMH0356 and LMH0302 cable driver. All that
is required is a 100Ω differential termination as shown. The resistor should be placed as close to the LMH0302
input as possible. If desired, this network may be terminated with two 50Ω resistors and a center tap capacitor to
ground in place of the single 100Ω resistor.
The LMH0356 has multiple ground connections, however; the primary ground connection is through the large
exposed DAP. The DAP must be connected to ground for proper operation of the LMH0356.
Figure 7. DC Input Interface
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Product Folder Links: LMH0356