• State Resolved
  • Locked Locked
  • Replies 9 replies
  • Subscribers 49 subscribers
  • Views 2154 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.

AMC3302: AMC3302 Didn't Work

Ulin
Prodigy 220 points

Part Number: AMC3302
Other Parts Discussed in Thread: AMC1301, OPA376

Dear Expert

I Just bought Isolated Amplifier AMC3302  (±50-mV Input, Reinforced Isolated Amplifier With Integrated DC/DC Converter), planned to be connected directly to 250uOhm Shunt Resistor for Motor Control Amplication.

I have previous experience with AMC1301 and it works very well with +-250mV input, I inject directly to INP & INN with function generator (sinusiodal waveform)

 

but since i change the design with AMC3302 the IC's output just stay 1.65V DC voltage means, the amplifier didn't recognize input signal (generated with function generator), maybe my schematic just wrong and need tobe corrected. please have review and give feedback. thank you

  • 0
    TI__Guru**** 182761 points

    Hi Abdin,

    I'm sorry to hear that you are having trouble with the AMC3302!  I'm not familiar with this these PCB's, are they your own design?

  • 0 in reply to Tom Hendrick
    Prodigy 220 points

    Dear Tom

    Yes, sure, I have design it by my self

    Thanks

    BR

    Abdin

  • 0 in reply to Ulin
    TI__Guru**** 182761 points

    Hi Abdin,

    I take it back, I see that you have OUTn tied to ground, please cut that trace.  The AMC3302 has a true differential output and they should not be shorted directly to ground.

  • 0 in reply to Tom Hendrick
    Prodigy 220 points

    Hi Tom

    Ok i will cut it with a cutter then try to powering up again this afternoon, i  will let you know the result, hope this will solved the problem. my previous experience with AMC1301 i just connected OUTN to Gnd to have single ended differential since uC also has single ended ADC. but its OK i will give it try.

    Thank you

    BR
    Abdin

  • 0 in reply to Ulin
    Guru 140200 points

    Hi Abdin,

    and - to achieve proper common mode rejection and suppression of switching noise - don't forget to add a differential amplifier to the output of AMC3302 like shown here:

    or here:

    This is mandatory :-)

    Alternatively, an ADC with differential inputs can also be connected, of course.

    Kai

  • 0 in reply to Ulin
    Prodigy 220 points

    Dear Tom

    still didn't work, i let the OUTN just floating, i measure OUTP with ground reference and still get flat signal, i also attached PDF file my report in attachment or as shown below (maybe to small please download the attachment)

    Thanks

    BR

    Abdin

    The input signal 50mV VPP.pdf

  • 0 in reply to Ulin
    TI__Guru 60022 points

    Hi Abdin,

    As an early debug step, try shorting both inputs to GND and verify that VOUTP is 1.44V.

    You may need to drop the signal from the signal generator across a resistor instead of direct connection to the inputs. The differential input resistance of the AMC3302 is significantly lower compared to the AMC1301 and your signal generator may be struggling to source that much current. 

  • 0 in reply to Alexander Smith
    Prodigy 220 points

    Dear Tom, Kai and Alex

    I made very big mistake with my function generator. it setting with offset 1.65V :)  -- (LoL)

    I just  set it back to 0.00V offset. the schematic and circuit already correct at first place, just how to test the AMC it wasn't

    I know the consequence just using OUTP only would not get the true potential of fully differential output (i got just 1VPP sine signal because i measure OUTP refer to gnd instead OUTP and OUTN) the next hardware revision would be equiped with OPA376 or equivalent to get full swing of 0 - 3.3V sine signal.

    Thank you very much guys for helping me and give lot reference, i appreciate it very much

    BR

    Abdin

  • 0 in reply to Ulin
    Guru 140200 points

    Good luck :-)

    Kai