LMH0002_08 Datasheet, PDF (4/6 Pages) National Semiconductor (TI) – SMPTE 292M / 259M Serial Digital Cable Driver

Device Operation
INPUT INTERFACING
The LMH0002 accepts either differential or single-ended in-
put. The inputs are self-biased, allowing for simple AC or DC
coupling. DC-coupled inputs must be kept within the specified
common-mode range. SDI and SDI are self-biased at ap-
proximately 2.1V with V_CC = 3.3V. Figure 1 shows the differ-
ential input stage for SDI and SDI.
OUTPUT INTERFACING
The LMH0002 uses current mode outputs. Single-ended out-
put levels are 800 mV_P-P into 75Ω AC-coupled coaxial cable
(with R_REF = 750Ω). Output level is controlled by the value of
the R_REF resistor connected between the R_REF pin and V_CC.
The R_REF resistor should be placed as close as possible to
the R_REF pin. In addition, the copper in the plane layers below
the R_REF network should be removed to minimize parasitic
capacitance.
OUTPUT SLEW RATE CONTROL
The LMH0002 output rise and fall times are selectable for ei-
ther SMPTE 259M or SMPTE 292M compliance via the SD/
HD pin. For slower rise and fall times, or SMPTE 259M com-
pliance, SD/HD is set high. For faster rise and fall times, or
SMPTE 292M compliance, SD/HD is set low.
REPLACING THE GENNUM GS1528, GS1528A, and
GS1578A
The LMH0002MA is form-fit-function compatible with the
Gennum GS1528 and GS1528A. The LMH0002SQ is form-
fit-function compatible with the Gennum GS1578A.
20176104
FIGURE 1. Differential Input Stage for SDI and SDI.
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