M21418_15 Datasheet, PDF (6/22 Pages) M/A-COM Technology Solutions, Inc. – HD/SD and 3G/HD/SD-SDI Cable Drivers

M21418/M21428
HD/SD and 3G/HD/SD-SDI Cable Drivers
Rev V6
1.0 Functional Description
1.1
Features
1.1.1
HD-SDI and SD-SDI Slew-rate Selection
The output slew rate of the M21418 and M21428 are selectable to conform with the different SD-SDI and HD-SDI
specifications, in the case of the M21428 this includes 3G-SDI. With SD/HD = Low, rise/fall time is typically 100 ps.
The slew rate will vary depending on the output matching network and connector used.
With SD/HD = High, for standard definition (143 to 540 Mbps) applications, the rise/fall time is typically 600 ps,
which is compliant with SMPE 259M and SMPTE 344M.
1.1.2
Output Amplitude Adjustment
For SMPTE compliance, an external 750  ±1% resistor at RSET to AV_DD is recommended for a swing level of
800 mV within a tolerance that is less than ±10% which meets SMPTE requirements. The output amplitude can
also be adjusted to range from 500 to 1600 mV_PP single ended using the following formula:
Output Swing = (600/RSET) [RSET in k] (in mV_PP, Single Ended)
The actual swing is set as a function of the IC supply voltage, the external termination voltage and the limitations
are shown in Table 1-1. For a 3.3 V minimum termination voltage, the IC can be SMPTE compliant for all supply
voltages. In applications where lossy matching or splitting networks are used, the M21418/M21428 offers
additional gain of up to 1600 mV_PP swings. When using swings in excess of 1200 mV, there will be an increase in
rise and fall times.
Table 1-1. Output Swing vs. Supply and Termination Voltage
AV_DD (V)
AV_DDTERM (V)
Maximum Swing
(Single-ended mVp–p)
2.5–3.3 V
3.3 V
1200 mV
2.5–3.3 V
5.0 V
1600 mV
Minimum Swing
(Single-ended mVp–p)
500 mV
500 mV
6
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