lmc662c-mdc National Semiconductor Corporation, lmc662c-mdc Datasheet - Page 9

• Manufacturer Part Number: lmc662c-mdc
• Description: Cmos Dual Operational Amplifier
• Manufacturer: National Semiconductor Corporation

Application Hints
dard op-amp configurations. If both inputs are active and at
high impedance, the guard can be tied to ground and still
provide some protection; see Figure 9.
FIGURE 7. Guard Ring Connections: Non-Inverting
FIGURE 6. Guard Ring Connections: Inverting
FIGURE 5. Example, using the LMC660,
of Guard Ring in P.C. Board Layout
Amplifier
Amplifier
(Continued)
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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
insulator. 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
10.
(Input pins are lifted out of PC board and soldered directly to components.
All other pins connected to PC board.)
FIGURE 9. Guard Ring Connections: Howland Current
FIGURE 8. Guard Ring Connections: Follower
FIGURE 10. Air Wiring
Pump
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