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INA3221 function issues

Mickey Zhang
Genius 12080 points
Other Parts Discussed in Thread: INA3221, INA250, INA226

Hi Team,

The customer wants to use INA3221. 

Q1:  Is INA3221 able to monitor the power supply voltage and to detect if there is sharp drop at some moment?

Q2: Is it fast enough to capture a sudden sharp drop in voltage?

Q3: As in the user guide, there is no timing information shows on the software interface. But if they need to record the voltage against time, is the timing information available from this design?

Q4: He needs to detect the voltage and the current are as belows. +5V/7A; +24V/2.7A;+12V/2.9MA;+24v/2.7MA.  Can INA3221 be OK?

  • 0
    TI__Genius 15760 points
    Hi Mickey,

    Q1: Yes. INA3221 is able to monitor bus voltages from 0V to 26V. They can use the PV (Power Alert) to detect chnages in the bus. The device should be configured on continuous conversion mode to be able to detect voltages changes.

    Q2: How fast it is done....depends in conversion time selection.

    Q3: In the software, you can press USB Controls (Top Left) > Start Graph Log. This will create an csv file and you should be able to see your data log.

    Q4: Please note that INA3221 is only 3 channels, not 4. He was looking for a single device solution? INA3221 can handle all those bus voltages that you have listed and if they chose appropriate shunt resistors they will be able to measure the currents they have.

    Hope this is helpful!
    Regards
  • 0 in reply to Mayrim Verdejo
    TI__Genius 12080 points

    Hi Mayrim,
    Thanks for your reply.

    Q1:I see ADC conversion time in 7.5 Electrical Characteristics of the data sheet. Is the conversion time what you said ADC conversion time? If not, please indicate which is the conversion time in the data sheet.

    Q2: I want to know which the measured current range is for INA3221. Does it depend on shunt resistors ?
    If it does, how to select the value of the shunt resistors when the customer measure the currents they have(7A,2.7A,2.9mA,,2.7mA). What is the range for the shunt resistors?

    Q3: Look the attachment. How does INA3221 detect the  current? What is Load1, Load2 and Load3? Are Load1, Load2 and Load3 the resistors? Why  Load1  needs to be connected to the R1? Can Load1 be removed? Is R1 the shunt resistor?

  • 0 in reply to Mickey Zhang
    TI__Genius 15760 points
    Dear Mickey,

    Some of the questions relates on how an INA works I already provided to you in previous post. We have a training series videos that I would like you to review if you have the time. It will help you understand customer requirements related to current sensing. If not you can give me a call and I am happy to walk you through the main features.
    This is the link to the previous post where I shared with you how INAs measure current and why the current is dependent on the shunt resistor:
    e2e.ti.com/.../1954418

    Q1) Correct, that is the conversion time I am referring to.
    Q2) As I mentioned in previous post, only the INA250 have a current range due to Rshunt inside of the device. The other INAs current range depends on the shunt selection. There are few considerations that need to be taken in consideration when selecting the shunt. Please share with your customer so they decide/chose shunt resistor based on their parameters.
    training.ti.com/getting-started-current-sense-amplifiers-session-4-how-choose-appropriate-shunt-resistor

    Q3) The INA3221 performs two measurements on up to three power supplies of interest. The voltage developed from the load current passing through a shunt resistor creates a shunt voltage that is measured between the IN+ and IN– pins. The customer could use the value of the shunt resistor and divide it by the shunt resistor (in their coding) and that will give them the current. We have other digital devices such as INA226 that have a Current Register, meaning the current value is calculated internally in the INA but it requires user configuration (Also, INA226 is single channel). Load 1,2,and 3 represents the load the customer have on their system. R1 is the shunt resistor.

    Why you selected INA3221? They want a digital output device?
  • 0 in reply to Mayrim Verdejo
    TI__Genius 12080 points
    Hi Mayrim,
    Thanks for your reply. That is the customer selects INA3221.