TINA-TI

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.

INA333

Virtual instruments offer users the ability to select

(FREE DOWNLOAD SOFTWARE)

input waveforms and probe circuit nodes, voltages,

and waveforms, creating a dynamic quick-start tool.

Using TINA-TI SPICE-Based Analog Simulation

Program with the INA333

Figure 38 and Figure 39 show example TINA-TI

circuits for the INA333 that can be used to develop,

TINA is a simple, powerful, and easy-to-use circuit

modify, and assess the circuit design for specific

simulation program based on a SPICE engine.

applications. Links to download these simulation files

TINA-TI is a free, fully functional version of the TINA

are given below.

software, preloaded with a library of macromodels in

addition to a range of both passive and active

NOTE: these files require that either the TINA

models. It provides all the conventional dc, transient,

software (from DesignSoft) or TINA-TI software be

and frequency domain analysis of SPICE as well as

installed. Download the free TINA-TI software from

additional design capabilities.

the TINA-TI folder.

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.

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

Figure 38. Low-Power Log Function Circuit for Portable Battery-Powered Systems

(Example Glucose Meter)

To download a compressed file that contains the TINA-TI simulation file for this circuit, click the following link:

Log Circuit.

16

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Product Folder Link(s): INA333