LM2437 National Semiconductor Corporation, LM2437 Datasheet - Page 6

• Manufacturer Part Number: LM2437
• Description: LM2437 - Monolithic Triple 7.5 NS CRT Driver, Package: to 220, Pin Nb=9
• Manufacturer: National Semiconductor Corporation

www.national.com
Application Hints
good example of a layout that can be used as a guide for fu-
ture layouts. Note the location of the following components:
The routing of the LM2437 outputs to the CRT is very critical
to achieving optimum performance. Figure 12 shows the
routing and component placement from pin 1 of the LM2437
to the blue cathode. Note that the components are placed so
that they almost line up from the output pin of the LM2437 to
the blue cathode pin of the CRT connector. This is done to
• C55 — V
• C43, C44 — V
• C53–C56 — V
and ground pins
8 and ground
V
CC
clamp diodes. Very important for arc protection.
CC
bypass capacitor, located very close to pin 4
BB
CC
bypass capacitors, located close to pin
bypass capacitors, near LM2437 and
(Continued)
6
minimize the length of the video path between these two
components. Note also that D14, D15, R29 and D13 are
placed to minimize the size of the video nodes that they are
attached to. This minimizes parasitic capacitance in the
video path and also enhances the effectiveness of the pro-
tection diodes. The anode of protection diode D14 is con-
nected directly to a section of the the ground plane that has
a short and direct path to the LM2437 ground pins. The cath-
ode of D15 is connected to V
pacitor C55 (see Figure 12 ) which is connected to the same
section of the ground plane as D14. The diode placement
and routing is very important for minimizing the voltage
stress on the LM2437 during an arcover event. Lastly, notice
that S3 is placed very close to the blue cathode and is tied
directly to CRT ground.
CC
very close to decoupling ca-