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INA226: INA226 ALERT response time

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Replies: 3

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Part Number: INA226

Hi team,

 

I can only found little description on response time of INA226 Alert pin(when over current or voltage happened), the only description is as below:

 

And it`s seem not right, when CT time is 1.1ms, alert response time is about 100us, but when CT time is 140us, response time is 1ms.

I don`t know if this data is right, and do you have response time description of INA226 alert pin@ different CT time?

Thanks very much.

 

Best Regards,

Sunny 

  • Hello Sunny,

    You are correct. The conversion times for Figures 28 and 29 need to be swapped in the datasheet. So Figure 28 is for when conversion time is 140us and Figure 29 is for 1.1ms conversion time.

    You can refer to Figure 19 to see that the ALERT limit is being checked after every single conversion. So if device is only measuring shunt voltage, the absolute maximum alert response time will always be < 2*t_ct. If the bus voltage is being measured, then the maximum alert response time for a shunt voltage limit event is < 2*t_ct_shunt + t_ct_bus.

    Usually the alert will respond within one conversion cycle as seen in Figures 28 and 29, but theoretically it could be more than one conversion cycle if the shunt voltage is very close to the limit and ramping up to the limit very slowly causing the ADC to read an average value just below the limit for the first cycle. For the second cycle the ADC will have the full conversion time to measure a shunt value greater than the limit.This phenomenon should be heavily dependent upon how the limit is set by the engineer and how the load current reaches its over current condition.

    I hope this helps.

    Sincerely,

    Peter

  • In reply to Peter Iliya:

    Hi Peter,

    Many thanks for your detail comments, it`s very clear.

    Regards, Sunny

  • In reply to Sunny Qin:

    Hey Sunny,

    You're welcome.

    Best,

    Peter