LM1207AN National Semiconductor, LM1207AN Datasheet - Page 21

• Manufacturer Part Number: LM1207AN
• Manufacturer: National Semiconductor

Specifications of LM1207AN

• Power Supply Requirement: Single
• Dual Supply Voltage (typ): Not RequiredV
• Dual Supply Voltage (min): Not RequiredV
• Dual Supply Voltage (max): Not RequiredV
• Mounting: Through Hole
• Lead Free Status / RoHS Status: Not Compliant

Applications of the
LM1205A/LM1207A
turned on. 100 resistors are not recommended at the video
inputs because this resistance value will start to roll off the
frequency response of the LM1205A/LM1207A.
Note that the layout shown in Figure 16 does have a very ex-
tensive ground plane. One must remember that the
LM1205A/LM1207A is a 130 MHz/85 MHz part and a single
sided board is difficult to successfully design. A ground plane
similar to the layout shown in Figure 16 must be provided for
good performance of the LM1205A/LM1207A when using ei-
ther a single sided or double sided board. The layout of this
board demonstrates the importance of grounding. The re-
sults of this layout are shown in Figure 17 through Figure 20 .
In these photographs the LM1205A rise time was 2.25 ns
and its fall time was 3.00 ns. For the LM1207A, the rise time
was 4.10 ns and the fall time 3.85 ns. The output was a 4
V
*Note: All video inputs MUST have a series 30
PP
signal and the cutoff voltage was set to 2V. The over-
(Continued)
resistor for protection against EOS (Electrical Over Stress).
FIGURE 15. Demonstration Board Schematic
21
shoot will subsequently be filtered out by the loading effects
of the CRT driver stage and the CRT itself. When the
LM1205A/LM1207A is designed into a video board one must
keep the ground to the CRT driver stage separate from the
ground of the LM1205A/LM1207A, connecting the two
grounds together only at one point. National Semiconductor
also manufactures a line of CRT drivers. Please contact Na-
tional for additional information. These drivers greatly sim-
plify the driver design allowing for shorter design cycles. Of
course the LM1205A/LM1207A can also be designed with a
discrete driver stage. Figure 21 shows a design using a
simple cascode CRT driver. The LM1205A/LM1207A block
would be the same schematic as shown in Figure 15 .
REFERENCES
Zahid Rahim, “Guide to CRT Video Design,” Application
Note 861, National Semiconductor Corp., Jan. 1993
Ott, Henry W. Noise Reduction Techniques in Electronic
Systems, John Wiley & Sons, New York, 1976
DS012866-23
www.national.com