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Original question:

INA232: How long for alert to assert during fault condition

INA232: The actual alarm time is twice as long as that indicated in the specification.

Nick Lu
Prodigy 40 points
Part Number: INA232
Other Parts Discussed in Thread: INA237, INA238, INA228

Tool/software:

Register Value：
0x00 = 0x4007
0x06 = 0x8000
0x07 = 0xFA0 (1A triggers alarm)
CH1：Current change 0-3A，0.3A/us，cycle = 10ms，Duty = 50%
CH2：Alarm status
Alarm response time is between 60us~354us
According to the specification, the theoretical maximum conversion time is 280us, and the actual maximum value is 354us. Is the information written in which register incorrect?
  • 0
    TI__Mastermind 23770 points

    Hello Nick,

    The maximum response time shown in the datasheet is for when there is only one conversion channel active. If you have conversions enabled on another channel, then you add that conversion time to the maximum response time. So in this case since you have conversion enabled for both shunt and bus, with 140µs on each, the response time would be less than 280µs + 140µs = 420µs.

    Regards,

    Mitch

  • 0 in reply to Mitch M
    Prodigy 40 points

    How to change: Set register 0x0 to 0x4005 and keep other settings unchanged?

  • 0 in reply to Nick Lu
    TI__Mastermind 23770 points

    Hey Nick,

    Yes, that would put the device in continuous shunt voltage only, and the alert would respond faster for the shunt voltage. However, then you would not have BUS voltage data. 

    If you are open to changing devices, then you could switch to the INA228, INA238, or INA237 which are faster devices, so you may be able to get shunt and bus voltage within your desired timeframe.

    Regards,

    Mitch

  • 0 in reply to Mitch M
    Prodigy 40 points

    OK，Thank you so much.

    I tested INA237EVM, the maximum alarm response time is 68us.

    （Current change 0-3A，0.3A/us，cycle = 10ms，Duty = 50%；Set 2.9A overcurrent trigger）

  • 0 in reply to Nick Lu
    TI__Mastermind 23770 points

    You're welcome!