LMC6032 Datasheet, PDF (9/13 Pages) National Semiconductor (TI) – CMOS Dual Operational Amplifier

Application Hints (Continued)
DS011135-11
(Input pins are lifted out of PC board and soldered directly to components.
All other pins connected to PC board.)
FIGURE 7. Air Wiring
BIAS CURRENT TESTING
The test method of Figure 8 is appropriate for bench-testing
bias current with reasonable accuracy. To understand its op-
eration, first close switch S2 momentarily. When S2 is
opened, then
DS011135-12
FIGURE 8. Simple Input Bias Current Test Circuit
A suitable capacitor for C2 would be a 5 pF or 10 pF silver
mica, NPO ceramic, or air-dielectric. When determining the
magnitude of I_b−, the leakage of the capacitor and socket
must be taken into account. Switch S2 should be left shorted
most of the time, or else the dielectric absorption of the ca-
pacitor C2 could cause errors.
Similarly, if S1 is shorted momentarily (while leaving S2
shorted)
where C_x is the stray capacitance at the + input.
Typical Single-Supply Applications (V⁺ = 5.0 V_DC)
Additional single-supply applications ideas can be found in
and R4 = R7.
the LM358 datasheet. The LMC6032 is pin-for-pin compat-
ible with the LM358 and offers greater bandwidth and input
resistance over the LM358. These features will improve the
performance of many existing single-supply applications.
Note, however, that the supply voltage range of the
LMC6032 is smaller than that of the LM358.
= 100 for circuit shown.
For good CMRR over temperature, low drift resistors should
be used. Matching of R3 to R6 and R4 to R7 affects CMRR.
Gain may be adjusted through R2. CMRR may be adjusted
through R7.
Instrumentation Amplifier
Sine-Wave Oscillator
if R1 = R5;
R3 = R6,
DS011135-14
DS011135-15
Oscillator frequency is determined by R1, R2, C1, and C2:
f_OSC = 1/2πRC
where R = R1 = R2 and C = C1 = C2.
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