LMC6492BEM NSC [National Semiconductor], LMC6492BEM Datasheet - Page 13

• Manufacturer Part Number: LMC6492BEM
• Description: CMOS Rail-to-Rail Input and Output Operational Amplifier
• Manufacturer: NSC [National Semiconductor]

Application Notes
The designer should be aware that when it is inappropriate
to lay out a PC board for the sake of just a few circuits, there
is another technique which is even better than a guard ring
on a PC board: Don’t insert the amplifier’s input pin into the
board at all, but bend it up in the air and use only air as an in-
sulator. Air is an excellent insulator. In this case you may
have to forego some of the advantages of PC board con-
struction, but the advantages are sometimes well worth the
effort of using point-to-point up-in-the-air wiring. See Figure
8 .
FIGURE 7. Typical Connections of Guard Rings
Non-Inverting Amplifier
Inverting Amplifier
Follower
(Continued)
DS012049-16
DS012049-14
DS012049-15
FIGURE 6. Examples of Guard
Ring in PC Board Layout
13
(Input pins are lifted out of PC board and soldered directly to components.
All other pins connected to PC board).
Application Circuits
Where: V
(V
1
+ V
DC Summing Amplifier (V
2
0
= V
(V
3
1
+ V
+ V
DS012049-13
4
) to keep V
2
− V
FIGURE 8. Air Wiring
3
– V
4
0
>
0V
DC
IN
0V
DC
and V
DS012049-17
DS012049-18
O
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V
DC