• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 47 subscribers
  • Views 4574 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Help with INA333 ECG Circuit

Richard Norling
Prodigy 10 points
Other Parts Discussed in Thread: TINA-TI, INA333, OPA333

6712.ECG_circuit.TSC

I've attached the TINA-TI circuit I've been working on. Im no expert in the electronics field or the medical engineering so I am having a hard time figuring out how to construct my ECG circuit. This signal will be connected to an Arduino, so i want the Vout to lie between 0V and 5V, to use the whole workspace of the A2D in the Arduino.

A couple i things i wonder about:

When i run a Transient-analysis, the graph tells me that my Vout is between 2.50V and 2.50V and i cant seem to figure it out. I want the signals virtual ground to be 2,5V (or maybe less) and the signal to swing from 0V to 5V.

Im also unsure about the supply minus voltage on the INA333 and the OPA333. Which should be me virtual ground, which should be ground or if some should be negative Vcc. As I've already mention my electronics skills are not good, so excuse me for any obvious mistakes.

Please help me achieve my project goal!

Sincerely // Richard

  • 0
    TI__Mastermind 25865 points

    Hello Richard,

    Here are a few observations:

    a)  Your inputs (ECG, LF Noise, and HF Noise) do not have any reference.  Typically the body is driven to a known voltage.  It is common practice to use a right-leg drive circuit, as shown here:


    b)  The INA333 and OPA333's are powered with 'VCC' and 'VGND' where VCC=5V and VGND=2.5V.  This would mean that the output can only swing between 2.5V and 5V.  Generally it's advisable to power the devices with 5V (or 3.3V) and ground (0V).

    Here is a link to a Wiki that you may find useful:

    http://e2e.ti.com/support/amplifiers/precision_amplifiers/w/design_notes/2437.ecg-heart-signal-acquisition.aspx

    It has some links at the bottom with a lot of additional information.  

    Also, here is a link to a university design team that we sponsored who built and tested a similar ECG circuit.  Perhaps you will find their documents useful.

    http://www.egr.msu.edu/classes/ece480/capstone/spring13/group03/index.html



    I hope this helps!