• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 47 subscribers
  • Views 313 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.

INA240: Use Cases

iConduct
Expert 5815 points
Part Number: INA240


Team,

Please see the customer's question below:


I want to use single setting with fixed Rsense and Fixed gain (20 to 200 which ever suits). Output voltage 1.0V-3.0V range where Rsense will be in series to load:


1. Power supply output 0.8V-3.0V. If Rsense is 5.0mohm and in high-side sensing. What is the minimum Load current  we can accurately sense. What would be the gain setting. Can REF1/REF2 be tied to GND?

2.  Power output 0.8V-3.0V. If Rsense is 5.0mohm.  and in high-side sensing. What is the maximum Load current we can accurately sense with the gain setting from #1.  Can REF1/REF2 follow #1 setting to GND.

3. Can INA240 drive high capacitive load? How high it can handle? Should there be a series R in output to handle 200pF-1000pF load? If so, what is Rseries in output? How this will be used in application (can you shown the connections). Will this high capacitive load works in #1 and #2.

4. Can I get spice models for this amp with all gain settings  (20-200).

5. How fast the output changes can be tracked? How much wait time needed in between measurement? What is amp's response time given lower 300KHZ bandwidth

Your support would be greatly appreciated.

Regards,

Sem Amesawu

  • 0
    TI__Mastermind 26335 points

    Hello iConduct,

    Thanks for reaching out on the forum.

    1. The INA240 needs a minimum supply of 2.7V. The minimum load depends on the amount of error you can tolerate.  All current measurements will have some error.  The error will increase as the load decreases.  Below shows an error curve for certain operating conditions.  How, I chose the upper load limit will be discussed in #2.  The error curve tool can be found on the right side of the product page.

    2. The maximum load is determined by your device supply, which is roughly equivalent to the max output.  For the largest load, you will need to use the smallest gain (20V/V).  Thereupon the max load is supply/gain/Rshunt = 3V/(20V/V)/(0.005ohm)=30A.  This is assuming your REF pins are tied to ground.  Otherwise max load will be (3V-REF bias point)/(20V/V)/(0.005ohm)

    3. We have a specification for the capacitive load in the electrical characteristics table of the datasheet. I am including it below.  For 1nF capacitive load or higher, I would add a resistor that coupled with the capacitive load creates a filter with satisfactory bandwidth for your customer's needs.

    4.  TINA spice models are available here.

    5. The slew rate is also available in the electrical characteristics table of the datasheet.  Figure 20 in the datasheet also has a measured step response of the INA240.