11

LMV321TP/LMV358TP/LMV324TP

40μA, 1.27MHz, Micro-Power Rail-to-Rail I/O Op Amps

www.3peakic.com.cn

REV A.02

A variation in temperature across the PCB can cause a mismatch in the Seebeck voltages at solder joints and

other points where dissimilar metals are in contact, resulting in thermal voltage errors. To minimize these

thermocouple effects, orient resistors so heat sources warm both ends equally. Input signal paths should contain

matching numbers and types of components, where possible to match the number and type of thermocouple

junctions. For example, dummy components such as zero value resistors can be used to match real resistors in

the opposite input path. Matching components should be located in close proximity and should be oriented in the

same manner. Ensure leads are of equal length so that thermal conduction is in equilibrium. Keep heat sources

on the PCB as far away from amplifier input circuitry as is practical.

The use of a ground plane is highly recommended. A ground plane reduces EMI noise and also helps to maintain

a constant temperature across the circuit board.

Instrumentation Amplifier

The LMV321TP/358TP/324TP OPA is well suited for conditioning sensor signals in battery-powered applications.

Figure 4 shows a two op-amp instrumentation amplifier, using the LMV321TP/358TP/324TP OPA.

The circuit works well for applications requiring rejection of Common Mode noise at higher gains. The reference

11

12

2

2

=(

)(1

)

OUT

REF

G

RR

V

V

V

V

RR









Figure 4

Gain-of-100 Amplifier Circuit

Figure 5 shows a Gain-of-100 amplifier circuit using two LMV321TP/358TP/324TP OPAs.

It draws 74uA total

current from supply rail, and has a -3dB frequency at 100kHz. Figure 6 shows the small signal frequency

response of the circuit.

90.9k

90.9k

10k

10k

-0.9V

+0.9V

Figure 5: 100k

Hz, 74μA Gain-of-100 Amplifier