Rset 2.5M

VoA2

VoA1

-

+

+

3

1

5

4

2

U5 OPA369

-

+

+

3

1

5

4

2

U6 OPA369

1/2ofmatched

monolithicdual

NPNtransistors

(example:MMDT3904)

Input I 10n

V

+

VM1

V1 5

uC Vref/2 2.5

Vdiff

Vout

+

-

+

U1 OPA335

R8 10k

+

RG

RG V+

V-

Ref

_

Out

2

1

8

3

6

7

5

4

U1 INA333

1/2ofmatched

monolithicdual

NPNtransistors

(example:MMDT3904)

NOTE: Temperaturecompensation

ofloggingtransistorsisnotshown.

Optionalbufferfordriving

SARconverterswith

samplingsystemsof

33kHz.

³

RELATEDPRODUCTS

Formonolithiclogarithmicamplifiers(suchasLOG112orLOG114)seethelinkinfootnote1.

21

INA333

www.ti.com

SBOS445C – JULY 2008 – REVISED DECEMBER 2015

Product Folder Links: INA333

Submit Documentation Feedback

Copyright © 2008–2015, Texas Instruments Incorporated

11 Device and Documentation Support

11.1 Device Support

11.1.1 Development Support

11.1.1.1 TINA-TI (Free Download Software)

Using TINA-TI SPICE-Based Analog Simulation Program with the INA333

TINA is a simple, powerful, and easy-to-use circuit simulation program based on a SPICE engine. TINA-TI is a

free, fully functional version of the TINA software, preloaded with a library of macromodels in addition to a range

of both passive and active models. It provides all the conventional DC, transient, and frequency domain analysis

of SPICE as well as additional design capabilities.

Available as a free download from the Analog eLab Design Center, TINA-TI offers extensive post-processing

capability that allows users to format results in a variety of ways.

Virtual instruments offer users the ability to select input waveforms and probe circuit nodes, voltages, and

waveforms, creating a dynamic quick-start tool.

Figure 41 and Figure 42 show example TINA-TI circuits for the INA333 device that can be used to develop,

modify, and assess the circuit design for specific applications. Links to download these simulation files are given

below.

NOTE

These files require that either the TINA software (from DesignSoft) or TINA-TI software be

installed. Download the free TINA-TI software from the TINA-TI folder.

(1) The following link launches the TI logarithmic amplifiers web page: Logarithmic Amplifier Products Home Page

Figure 41. Low-Power Log Function Circuit for Portable Battery-Powered Systems

(Example Glucose Meter)