OBSOLETE

LM2402

SNOS445B – AUGUST 1999 – REVISED APRIL 2013

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TI Demonstration Board

Figure 12 and Figure 13 show routing and component placement on the TI LM2202/2402 demonstration board.

The schematic of the board is shown in Figure 11. This board provides a good example of a layout that can be

used as a guide for future layouts. Note the location of the following components:

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(Figure 12)

The routing of the LM2402 outputs to the CRT is very critical to achieving optimum performance. Figure 14

shows the routing and component placement from pin 1 to the blue cathode. Note that the components are

placed so that they almost line up from the output pin of the LM2402 to the blue 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

minimizes parasitic capacitance in the video path and also enhances 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

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.

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