LM2402T datasheet(6/11 Pages) NSC

6 / 11 page

Application Hints (Continued)

cathode pin of the CRT connector. This is done to minimize

the length of the video path between these two components.

The direct video path is shown in by a dark gray line through

the components and the PCB traces. Note also that D24,

D25, R58 and D19 are placed to keep the size of the video

nodes to a minimum (R58 is located under D19). This mini-

mizes parasitic capacitance in the video path and also en-

hances the effectiveness of the protection diodes. The traces

in the video nodes to these components are shown by the

white line. The anode of protection diode D25 is connected

directly to the ground plane giving a short and direct path to

the LM2402 ground pins. The cathode of D24 is connected

to V

CC very close to decoupling capacitor C78 (Figure 13)

which is connected to the same section of the ground plane

as D25. The diode placement and routing is very important

for minimizing the voltage stress on the LM2402 during an

arc-over event. Lastly, notice that S3 is placed very close to

the blue cathode and is tied directly to CRT ground.

LM2402T Scheda tecnica(PDF) 6 Page - National Semiconductor (TI)