LMC6492 datasheet(14/18 Pages) NSC

14 / 18 page

Application Circuits (Continued)

This low-pass filter circuit can be used as an anti-aliasing fil-

ter with the same supply as the A/D converter. Filter designs

can also take advantage of the LMC6492/4 ultra-low input

current. The ultra-low input current yields negligible offset er-

ror even when large value resistors are used. This in turn al-

lows the use of smaller valued capacitors which take less

board space and cost less.

Dielectric absorption and leakage is minimized by using a

polystyrene or polypropylene hold capacitor. The droop rate

is primarily determined by the value of C

H and diode leakage

current. Select low-leakage current diodes to minimize

drooping.

In a manifold absolute pressure sensor application, a strain

gauge is mounted on the intake manifold in the engine unit.

Manifold pressure causes the sensing resistors, R1, R2, R3

High Input Z, DC Differential Amplifier

DS012049-19

For

(CMRR depends on this resistor ratio match)

As shown: VO = 2(V2 −V1)

Photo Voltaic-Cell Amplifier

DS012049-20

Instrumentation Amplifier

DS012049-21

If R1 = R5, R3 = R6, and R4 = R7; then

∴A

V ≈ 100 for circuit shown (R2 = 9.3k).

Rail-to-Rail Single Supply Low Pass Filter

DS012049-22

Low Voltage Peak Detector with Rail-to-Rail Peak

Capture Range

DS012049-23

Pressure Sensor

DS012049-24

Rf = Rx

Rf >> R1, R2, R3, and R4

LMC6492 Datasheet(PDF) 14 Page - National Semiconductor (TI)