LMC6042IM/NOPB National Semiconductor, LMC6042IM/NOPB Datasheet - Page 10

• Manufacturer Part Number: LMC6042IM/NOPB
• Description: IC OP AMP CMOS DUAL MICRO 8-SOIC
• Manufacturer: National Semiconductor

Specifications of LMC6042IM/NOPB

• Amplifier Type: General Purpose
• Number Of Circuits: 2
• Output Type: Rail-to-Rail
• Slew Rate: 0.02 V/µs
• Gain Bandwidth Product: 100kHz
• Current - Input Bias: 0.002pA
• Voltage - Input Offset: 1000µV
• Current - Supply: 26µA
• Current - Output / Channel: 40mA
• Voltage - Supply, Single/dual (±): 4.5 V ~ 15.5 V, ±2.25 V ~ 7.75 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• -3db Bandwidth: -
• Other names: *LMC6042IM; *LMC6042IM/NOPB; LMC6042IM

Applications Hints
(Continued)
simple. First, the user must not ignore the surface leakage of
the PC board, even though it may sometimes appear accept-
ably low, because under conditions of high humidity or dust
or contamination, the surface leakage will be appreciable.
To minimize the effect of any surface leakage, lay out a ring
of foil completely surrounding the LMC6042’s inputs and the
terminals of capacitors, diodes, conductors, resistors, relay
terminals etc. connected to the op-amp’s inputs, as in Figure
4. To have a significant effect, guard rings should be placed
on both the top and bottom of the PC board. This PC foil
must then be connected to a voltage which is at the same
voltage as the amplifier inputs, since no leakage current can
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flow between two points at the same potential. For example,
Inverting Amplifier
Ω, which is nor-
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a PC board trace-to-pad resistance of 10
mally considered a very large resistance, could leak 5 pA if
the trace were a 5V bus adjacent to the pad of the input. This
would cause a 100 times degradation from the LMC6042’s
actual performance. However, if a guard ring is held within 5
Ω would
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mV of the inputs, then even a resistance of 10
cause only 0.05 pA of leakage current. See Figure 5 for
typical connections of guard rings for standard op-amp con-
figurations.
01113710
Non-Inverting Amplifier
01113709
Follower
FIGURE 5. Typical Connections of Guard Rings
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FIGURE 4. Example of Guard Ring
in P.C. Board Layout
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