LM1205N National Semiconductor, LM1205N Datasheet - Page 19

• Manufacturer Part Number: LM1205N
• Description: IC VIDEO AMP 130MHZ RGB 28DIP
• Manufacturer: National Semiconductor

Specifications of LM1205N

• Applications: General Purpose
• Number Of Circuits: 3
• -3db Bandwidth: 130MHz
• Current - Supply: 90mA
• Current - Output / Channel: 28mA
• Voltage - Supply, Single/dual (±): 10.8 V ~ 13.2 V
• Mounting Type: Through Hole
• Package / Case: 28-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: *LM1205N

Applications of the LM1205
is added to the Blank Gate and Clamp Gate inputs These
two resistors also limit the current during a voltage surge A
larger resistor is required because these inputs are DC cou-
pled allowing the current to continuously flow into these
inputs before the monitor is turned on 100
not recommended at the video inputs because this resist-
ance value will start to roll off the frequency response of the
LM1205
Note that the layout shown in Figure 16 does have a very
extensive ground plane One must remember that the
LM1205 is a 130 MHz part and a single sided board is diffi-
cult to successfully design A ground plane similar to the
layout shown in Figure 16 must be provided for good per-
formance of the LM1205 when using either a single sided or
double sided board The layout of this board demonstrates
the importance of grounding The results of this layout is
shown in Figures 17a and 17b In these photographs the
rise time was 2 30 ns and the fall time was 3 40 ns The
output was a 4 V
PP
signal and the cutoff voltage was set to
FIGURE 15 Demonstration Board Schematic
(Continued)
resistors are
19
Figure 18 shows a design using a simple cascode CRT driv-
Systems John Wiley
2V This overshoot will subsequently be filtered out by the
loading effects of the CRT driver stage and the CRT itself
When the LM1205 is designed into a video board one must
keep the ground to the CRT driver stage separate from the
ground of the LM1205 connecting the two grounds together
only at one point National Semiconductor also manufac-
tures a line of CRT drivers Please contact National for addi-
tional information These drivers greatly simplify the driver
design allowing for shorter design cycles Of course the
LM1205 can also be designed with a discrete driver stage
er The LM1205 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
Sons New York 1976
TL H 11831 – 19