Project Files of INA128 Instrumentation Amplifier Library for Proteus Simulation

INA128 INSTRUMENTATION AMPLIFIER LIBRARY FOR PROTEUS - V1.0 (an INA128 with a pop-up, for Proteus simulation)
Designed by The Engineering Projects
www.TheEngineeringProjects.com

IMPORTANT LINKS
Article (read it first - pictures, step by step, every feature explained):
  https://www.theengineeringprojects.com/2026/11/ina128-instrumentation-amplifier-library-for-proteus.html
Report a bug or suggest a feature (our forum):
  https://www.theengineeringprojects.com/forum/category/ina128-proteus-library
The demo runs on our Arduino UNO V4.0 (included) - working LEDs, RESET and a
built-in serial monitor, no Virtual Terminal to wire - its own article:
  https://www.theengineeringprojects.com/2026/10/arduino-uno-library-for-proteus-v40.html
Support us (the libraries are free):
  https://www.theengineeringprojects.com/donate

FILE STRUCTURE
INA128-TEP-v1.0/
|-- Proteus Library Files/
|   |-- ArduinoV4TEP.LIB                              201.9 KB   TEP Arduino boards V4.0 (UNO) -> LIBRARY
|   |-- TEPINA128.LIB                                  12.3 KB   the library -> LIBRARY folder
|   |-- TEPRESISTOR.LIB                               306.9 KB   a part the demo uses -> LIBRARY folder
|-- Proteus Model Files/
|   |-- TEPARDUINO.DLL                                883.5 KB   the Arduino board model -> MODELS folder
|   |-- TEPINA128.DLL                                 307.0 KB   the model -> MODELS folder
|   |-- TEPRESISTOR.DLL                               311.0 KB   its model -> MODELS folder
|-- Proteus Simulation/
|   |-- INA128_Demo.hex                                15.6 KB   the demo firmware
|   |-- INA128-Bridge-ArduinoUnoV4.pdsprj              23.3 KB   the demo project
|   |-- TEPARDUINO.DLL                                883.5 KB   copy of the board model
|   |-- TEPINA128.DLL                                 307.0 KB   copy of the model
|   |-- TEPRESISTOR.DLL                               311.0 KB   copy of its model
|-- Arduino Code/
|   |-- INA128_Demo/INA128_Demo.ino                     2.5 KB   the demo sketch (source of the .hex)
|-- README.txt                                        ~14.2 KB   this file
Total: 3.50 MB (unzipped). The C++ source code of the models is not included.

WHAT IS IT?
The INA128 instrumentation amplifier as the PDIP-8 chip itself, drawn at true scale (9.81 x 6.35 mm)
- our own drawing:
  * The black body on its side (the notch left, pin 1 bottom left): RG VIN- VIN+ V- along the
    bottom, RG V+ VO REF along the top, the pin
    names printed small inside (the two RG pins are RG1 and RG8 in the netlist).
  * The three-op-amp design as TI's datasheet gives the INA128 (the PDIP grade): the gain set by the
    resistor YOU wire between pins 1 and 8,
    G = 1 + 50 k / RG (open: G = 1), measured back from its current; VO = REF + G (VIN+ - VIN-); REF
    loaded by the internal 80 k; the
    internal amplifiers 2 V from each rail (the common-mode range), the output 1.4 V from each rail;
    offset 10 uV + 100 uV / G; CMRR 86 -
    130 dB; bandwidth 1.3 MHz (G = 1) to 20 kHz (G = 1000); 4 V/us; supply 4.5 - 36 V.
  * Click it at Run for the pop-up: the three amplifiers live, RG and the gain, VO - REF against G x
    the input over the last 3 s.
The body is drawn as on the real part and to true scale against our Arduino.
The TEP signature and the pop-up are TEP additions.

ONE DEVICE (search "INA128" in Pick Devices):
  INA128TEP     "INA128 Instrumentation Amp V1.0" in TEPINA128.LIB (Lab ICs > Instrumentation Amps),
  prefix U, model TEPINA128.DLL (analog).
The demo also uses our Resistor parts (TEPRESISTOR.LIB / TEPRESISTOR.DLL, in this package).

THE POP-UP
Click the part at Run. Tabs:
    Amplifier  A1 and A2 with RG and the 25 k feedback, A3 with REF and VO, their live voltages (red
    when the inside is at its limit),
               VO - REF against G x (VIN+ - VIN-) over 3 s, and eight live values (gain and RG,
               input, output, common mode, A1 / A2,
               CMRR, REF and supply).
    Graphs     the live values over the last 2, 6 or 15 s. Live / Freeze.
    Event log  every change and warning; filters All / Changes / Warnings, Pause, Clear
    Check      what the part is doing and what to look at, each with a verdict (green = fine, amber
    = check, red = wrong)
    Settings   theme, text size, open at Run, window size
    Help       report a bug, suggest a feature, article, updates, donate, forum; Copy diagnostics
    for a bug report

TEST STATUS
V1.0: verified in Proteus 8.5 on 7 Nov 2026 (the demo project as shipped: an A4 sheet, an Arduino UNO V4.0).
What the runs showed (the model's own numbers and the sketch's monitor):
  * The project loads and starts cleanly; the demo runs 13 simulated seconds in under three minutes
    on our PC (the pop-up open).
  * RG = 510 ohm between pins 1 and 8: the model measured RG 510.00 ohm from its current and G =
    99.0393 (1 + 50 k / 510 = 99.039).
  * D5 HIGH (220k into BP): VIN+ - VIN- = 5.6437 mV (the resistor sum: 5.669 mV; the rest is the
    UNO's pins loading BP); A1 2.2228 V,
    A2 2.7828 V; VO 3.0602 V, REF 2.5002 V: VO - REF = 0.5600 V = 99.04 x (5.6437 mV + the 10 uV
    offset) + 100 uV. The sketch: the bridge
    alone read 4.9 mV (one UNO step), the INA128's output 562.1 mV = 5.675 mV at the input; D5 LOW
    -562.1 mV. In the loop (13.04 s,
    D5 LOW): -5.6685 mV in, VO - REF -0.5603 V.
  * D6 HIGH (2.2M): the sketch read 53.8 mV = 0.543 mV at the input (0.568 mV by the resistors; one
    UNO step is 49 uV at the input).
  * Common mode (D7 + D8 through 10k into both sides): both inputs at 2.6188 V (+119 mV), the
    difference -13.8 uV: VO - REF -0.27 mV;
    the CMRR term at 125 dB (G = 99) is +6.7 uV at the output. The sketch read 0.0 mV for +119 and
    -119 mV.
  * D9 HIGH (47k): 26.304 mV asks for 2.6 V, but A2 reached 3.816 V and A1 1.210 V against the 2.00
    - 3.00 V the inside allows on 5 V:
    VO stopped at 3.5004 V, VO - REF +1.0001 V (the sketch: 1002.0 mV, -1002.0 mV for D9 LOW; the
    bridge alone read 24.4 mV). One
    input-stage limit logged (held 50 us or more), linear again when D9 was released.
  * REF from two 100 ohm, a stiff divider (50 ohm against the chip's 80 k): 2.5000 - 2.5003 V.
  * The pop-up: Amplifier (the three amplifiers live, RG and the gain measured, VO - REF against G x
    the input over 3 s), Graphs, Event
    log, Check - all four followed the run.

INSTALLATION (about 2 minutes)
1. Close Proteus. Extract the WHOLE ZIP to a normal folder (e.g. Desktop).
2. Copy everything in "Proteus Library Files" (TEPINA128.LIB, TEPRESISTOR.LIB and our Arduino
library V4.0, ArduinoV4TEP.LIB, with the ARDUINO UNO V4.0 used by the demo) to the LIBRARY folder of
Proteus, for example:
     C:\Program Files (x86)\Labcenter Electronics\Proteus 8 Professional\LIBRARY
   (use the folder that already holds Proteus's own .LIB files).
3. Copy TEPINA128.DLL, TEPRESISTOR.DLL and TEPARDUINO.DLL from "Proteus Model Files" to the MODELS
folder (...\Proteus 8 Professional\MODELS).
4. Delete TEPINA128.IDX from the LIBRARY folder if it is there (Proteus makes a new index).
5. Start Proteus. In Pick Devices (P) search "INA128".

RUN THE DEMO
"Proteus Simulation\INA128-Bridge-ArduinoUnoV4.pdsprj" (an A4 sheet) - keep the .hex file and the
DLLs beside the project.
  ARD1:   Arduino UNO V4.0 running INA128_Demo.hex, its serial monitor built in (window "TEP Arduino
  UNO - ARD1").
  U1:     the INA128 on 5 V. R1 - R4 1k: a Wheatstone bridge (BP = VIN+, BN = VIN-, both 2.5 V); R5
  510 ohm = RG (G = 99.04);
          R11 / R12 100 ohm: REF at 2.5 V.
  The UNO unbalances the bridge: D5 through R6 220k (+-5.67 mV), D6 through R7 2.2M (+0.57 mV), D7
  and D8 through R8 / R9 10k into
  both sides (+-119 mV common mode), D9 through R10 47k (+-26.3 mV - too much on 5 V). A0 reads VO,
  A1 REF, A2 BP, A3 BN.
  The sketch prints the bridge as the UNO sees it alone and the INA128's output for each state, then
  flips D5 every 300 ms.
Closed the monitor? Click the UNO's USB port.

WIRING (the same in Proteus and on a real board)
  V+ 4.5 - 36 V (the UNO's 5 V here), V- ground (or a negative supply); RG between pins 1 and 8; REF
  to a low impedance
  (ground, a reference or a buffered divider); keep both inputs and G x the input inside the range
  the pop-up shows.
REAL HARDWARE:
 * On a single 5 V supply the INA128's inside needs 2 V from each rail: the inputs must stay near
   2.5 V and the output within about +-0.5 V
   of REF at high gain; for 5 V systems a rail-to-rail part (INA333, INA826) fits better.
 * Drive REF from a low impedance: a reference or an op-amp buffer. A plain divider adds gain error
   and costs CMRR.
 * Low RG values for high gain make the wiring resistance part of RG.
 * The input bias current needs a path: a floating input (a thermocouple, AC coupling) needs a
   resistor to a mid voltage.

THE DEMO SKETCH ON THE SERIAL MONITOR (INA128_Demo V1.0, 9600 baud)
There are no commands. The sketch unbalances the bridge state by state, prints, then flips D5
forever.
EXPECTED MONITOR OUTPUT
  INA128 Instrumentation Amp - TEP
  D5 HIGH:    bridge 4.9 mV, out 562.1 mV = 5.675 mV in
  D6 HIGH:    bridge 0.0 mV, out 53.8 mV = 0.543 mV in
  CM +119 mV: bridge 0.0 mV, out 0.0 mV = 0.000 mV in
  D9 HIGH:    bridge 24.4 mV, out 1002.0 mV = 10.117 mV in

PROPERTIES (double-click the part > Edit Properties)
  Input offset voltage (VOS)           the input-referred offset, uV (10; the datasheet: 10 typical,
  50 max; the output adds 100 uV / G)
Every run starts again from the properties.

LINKS.INI (OPTIONAL)
The Help page cards of the pop-up open web pages. To point them somewhere else without a new DLL,
put a text file named links.ini next to TEPINA128.DLL with lines KEY=URL, for example:
  ARTICLE=https://www.theengineeringprojects.com/...
Keys: WEBSITE, FORUM, BUG_REPORT, FEATURE_REQUEST, ARTICLE, USER_GUIDE,
UPDATE_CHECK, DONATE. Only http:// and https:// links are used; lines starting
with # are comments.

TROUBLESHOOTING
* NO SUPPLY: V+ - V- is under 4 V; a warning below 4.5 V.
* G = 1: nothing between pins 1 and 8 - fit RG.
* INPUT STAGE AT ITS LIMIT: an internal amplifier needs more than the supply allows - lower the
  gain, or bring the inputs to mid-supply.
* OUTPUT AT ITS LIMIT: VO is within 1.4 V of a rail - move REF or lower the gain.
* The output is offset: REF is not where you think - measure it; a divider without a buffer sags.
* The part is not simulated: TEPINA128.DLL is missing from MODELS and from the project folder. No
  UNO / no monitor window: TEPARDUINO.DLL is missing, or click the UNO's USB port.

BUG REPORTS AND FEATURE REQUESTS
Please post them in our forum with a screenshot, the Serial Monitor text, the
simulation log and the pop-up's Copy diagnostics text:
  https://www.theengineeringprojects.com/forum/category/ina128-proteus-library

SUPPORT US
This library is free. If it saves you time, please support our work:
  https://www.theengineeringprojects.com/donate

WEBSITE
  https://www.theengineeringprojects.com/

LICENCES AND THIRD-PARTY NOTES
* The model (TEPINA128.DLL), the symbols and artwork, the other parts of ours in the demo and the
  Arduino Library V4.0 (ArduinoV4TEP.LIB / TEPARDUINO.DLL, with its built-in TEP Serial Monitor
  Advance) are made by The Engineering Projects. The models use only standard Windows libraries; no
  Visual C++ redistributable is needed.
  The C++ source code is not included.
* Arduino UNO V4.0 (ArduinoV4TEP.LIB / TEPARDUINO.DLL, our Arduino Library V4.0 - its
  microcontroller is Proteus's own AVR model): The Engineering Projects,
  https://www.theengineeringprojects.com/2026/10/arduino-uno-library-for-proteus-v40.html
* The .hex file is built from the demo sketch and the Arduino AVR core 1.8.6, which includes
  LGPL-licensed code; its source code is available at
  https://github.com/arduino/ArduinoCore-avr/tree/1.8.6
* Proteus is a product of Labcenter Electronics and is not included. Arduino is a trademark of Arduino SA.
  This library is not made or endorsed by Arduino or Labcenter.

REBUILDING THE FIRMWARE (OPTIONAL)
The HEX file is supplied; Arduino IDE is not needed to run the demo. To edit the sketch, open
Arduino Code\INA128_Demo\INA128_Demo.ino, select Arduino Uno and use Sketch > Export Compiled
Binary. Replace the simulation's .hex with the exported HEX. The sketch needs 5,674 bytes of flash
and 453 bytes of RAM.

MODEL SCOPE AND LIMITS
Modelled: the gain from the real RG (any value, open = 1), the internal amplifiers' range, the
output swing, REF's 80 k load, the
offset, the CMRR by gain, the bandwidth by gain, the slew rate, the bias current, the supply
current; limits logged when they last 50 us.
Not modelled: noise, drift, PSRR, the input protection, the output current limit (over 15 mA is
reported), the exact hexagon shape of
the common-mode range (a rectangle: 2 V from each rail inside, 1.4 V at the output).

VERSION
TEP INA128 library V1.0 (Nov 2026). Device INA128TEP (TEPINA128.LIB / TEPINA128.DLL). Demo sketch
INA128_Demo V1.0. Demo board: ARDUINO UNO V4.0 (TEP Arduino Library V4.0) with its built-in serial
monitor.