m21408 Mindspeed Technologies, m21408 Datasheet - Page 8

• Manufacturer Part Number: m21408
• Description: M21408/m21418/m21428 Sd, Hd/sd And 2xhd-sdi Cable Drivers
• Manufacturer: Mindspeed Technologies

1.2.2
The M21408/M21418/M21428 output buffer is an open collector buffer that is designed for a return loss of 15 dB at
SD and HD rates and 10 dB at 2xHD rates, using standard through-hole BNC connectors as typically employed in
broadcast video equipment. A typical output matching circuit is shown in
(ORL) is dependent on many factors such as the value and type of components used, PCB layout, PCB trace
lengths, and type of PCB di-electric, therefore, the recommendations in the figure below should be used as starting
guidelines only. Different output matching network topologies and different component values will result in different
ORL performance.
The M21408/M21418/M21428 has SD-SDI and HD-SDI rise/fall times that are typically faster than the legacy cable
driver devices but within the relevant SMPTE specification for additional margin in most designs. The faster output
slew rate results in a more open eye. The actual maximum output of the part depends on the applied IC voltage as
well as the external termination voltage for the load termination. The limitations are discussed in
Figure 1-3.
214x8-DSH-001-D
Typical Output Matching/Back-termination Circuit
High-speed Outputs
M21408
M21418
M21428
AV
DD
SDO
SDO
I
DD
Mindspeed Proprietary and Confidential
Mindspeed Technologies
75Ω
75Ω
I TERM
4.7 nH
4.7 nH
75Ω
75Ω
AV
DDTERM
4.7 uF
4.7 uF
®
Figure
BNC
BNC
1-3. The Output Return Loss
10 nF
Functional Description
Section
1.1.
3