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INA214: the propagation delay time of Input to output

Harry Ma
Intellectual 2200 points
Part Number: INA214
Other Parts Discussed in Thread: INA216, , INA281, INA280, INA181

Hi Team

My customer is using INA214A as the 12V output current sense Ap. they find the response time delay is different when they do dynamic load test. you can find the detailed test waveform and set-up.

Customer's questions are: why the delay for different input?  Can you explain the root-cause of this phenomenon?

INA214AIDCKR_Input&output delay.pdf

  • 0
    TI__Mastermind 32395 points

    Hey Harry,

    This phenomenon is explainable. The delay time (which is actually an overload recovery time) is inversely proportional to the load step amplitude. The reason is that as the load amplitude increases, the faster and harder the Vout is pushed out of saturation (Vout < 5mV = saturation). And if you push Vout of saturation faster, then the overload recovery delay time becomes shorter.

    Sincerely,

    Peter

  • 0 in reply to Peter Iliya
    TI__Intellectual 2200 points

    Hi Peter

    Thanks for your sharing, it helps a lot.

    You mentioned that Vout<5mv=saturation, you mean that INA216's output saturation voltage is 5mV? 

    so if Vin*G>5mv, the output will be saturation?

  • 0 in reply to Harry Ma
    TI__Mastermind 32395 points

    Hey Harry, 

    We guarantee that maximum swing to ground output voltage is 5 mV for all gain variants. So if VOUT > 5 mV, then output will be out of saturation, although it might not be linear or accurate.

    Sincerely,

    Peter

  • 0 in reply to Peter Iliya
    TI__Intellectual 2200 points

    Hi Peter

    Thanks! the system spec requires 10us delay, and the INA214 already has 8.5us nearly on full-load condition. Is there any way to optimized overload recovery time?

    Or Do you have any other recommendation with fast recovery time? I can promote it to customer. P2P is better. 

    How about INA281's recovery time? Do you have date of it? they also use this part for High CM voltage feature.

  • 0 in reply to Harry Ma
    TI__Mastermind 32395 points

    Hey Harry,

    The only way to improve this for INA214 is to provide a small reference voltage to REF pin (> 50mV). This will ensure OUT is always in linear region.

    The other option is to simply use a faster device such as INA181, INA280, or INA281. The INA181 is pin-to-pin compatible and has much better bandwidth and slew rate. You can also see that INA181 clearly recovers from inverting overloads much faster than INA214 (by about one order of magnitude) when comparing datasheet curves Figure 5-19 (INA214) and 6-33 (INA181)

    The INA280/INA281 (1 MHz BW) will have very fast response times as long as the input shunt voltage is not going negative (negative current). Here is a post where my colleague measured response times from 0mA to be < 1us.

    https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/1048966/ina293-q1-current-sense-amplifier-rise-time-prop-delay-and-response-time-data