• State Resolved
  • Locked Locked
  • Replies 8 replies
  • Answers 1 answer
  • Subscribers 49 subscribers
  • Views 723 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.

AMC1301 &AMC1302.Why there is one difference in the two pictures below which been circled ?which one is correct?

long han
Prodigy 50 points
Other Parts Discussed in Thread: AMC1301

If it was neccessary to connected GND1 and VINN in the picture at the right hand?why it is not conectted in the picture at the left hand?

  • +1
    Guru 140200 points

    Have you noticed figure 52 of datasheet of AMC1301? As you see there's no absolute must to directly connect the negative input VINN to GND1.

    The right schematic is only an example showing how the inputs can be connected in a certain application.

    Kai

  • 0 in reply to kai klaas69
    Prodigy 200 points

    Hello,

    does it mean that I can swap VINN & VINP (Fig. 54)?

    If none of VINP/VINN is connected to GND1 (floating), then simple VINP/VINN swapping will cause opposite (inverter) polatity of sensed current (voltage across a shunt)?

    Please, could you confirm there is really NO NEED to connect VINN to GND1.

    Thanks

    Petr Kadanik

  • +1 in reply to Petr Kadanik
    Guru 140200 points

    Hi Petr,

    kai klaas69 said:
    Have you noticed figure 52 of datasheet of AMC1301? As you see there's no absolute must to directly connect the negative input VINN to GND1.

    I didn't say "floating". I said that there's no must to directly connect the negative input VINN to GND1.

    Look at figure 52 of datasheet to see what I mean. Try to understand the meaning of R3'.

    Kai

  • 0 in reply to Petr Kadanik
    TI__Guru 55152 points

    Hi Petr,

    Best practice is to connect at least one of the inputs to the device ground and allow the other input to swing +/- with respect to the other input and GND. This ensures that the input voltage remains in the common-mode input range of the device and does not violate the absolute maximum voltage input rating. This is especially important for current measurement applications where the absolute voltage magnitude across the shunt can shift rapidly. 

    As Kai said, this is not a hard requirement, but it is the easiest way to ensure proper device operation. Thanks Kai! 

  • 0 in reply to Alexander Smith
    Prodigy 200 points

    Hello Alexander,

    thanks for your reply.

    I understand the best practice recommending to ground one of the inputs. What I want to do is swapping VINP and VINN inputs, so VINP (positive) will be connected to GND1. I expect output signal polarity to be inverted after this modification. Moreovere, it also will make my PCB routing easier. However, I need to be 100% sure that this modification (swapping VINP & VINN; while VINP is connected for GND1) will not cause none performance and functional degradation, but output signal polarity inversion.

    Could you please confirm?

    Thanks

    Petr

  • 0 in reply to Petr Kadanik
    TI__Guru 55152 points

    Hi Petr,

    This is fine, there will be no degradation in performance, only polarity inversion as you indicated. 

  • 0 in reply to Alexander Smith
    Prodigy 200 points

    Thanks. I will swap it in my next PCB iteration.

    ... and I will get back to you in case it doesn't work :-)

    SOLVED.

    Thanks

    Petr