LPC660AI National Semiconductor Corporation, LPC660AI Datasheet - Page 10

• Manufacturer Part Number: LPC660AI
• Description: LPC660 - Low Power CMOS Quad Operational Amplifier, Package: Soic Narrow, Pin Nb=14
• Manufacturer: National Semiconductor Corporation

www.national.com
Application Hints
This would cause a 100 times degradation from the
LPC660’s actual performance. However, if a guard ring is
held within 5 mV of the inputs, then even a resistance of
10
perhaps a minor (2:1) degradation of the amplifier’s
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
11
ohms would cause only 0.05 pA of leakage current, or
(a) Inverting Amplifier
(c) Follower
FIGURE 4. Example of Guard Ring in P.C. Board Layout using the LPC660
(Continued)
FIGURE 5. Guard Ring Connections
DS010547-20
DS010547-22
10
performance. See Figure 5a , Figure 5b , Figure 5c for typical
connections
configurations. If both inputs are active and at high
impedance, the guard can be tied to ground and still provide
some protection; see Figure 5d .
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
(d) Howland Current Pump
(b) Non-Inverting Amplifier
of
DS010547-19
guard
rings
for
standard
DS010547-23
DS010547-21
op-amp