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OPA388-Q1: Simulation - High speed over current detection

Dierk Bronner
Intellectual 1675 points
Part Number: OPA388-Q1
Other Parts Discussed in Thread: OPA388, TLV3201

Hello GPAMPs team,

my customer is interested in simulatie the High speed over current detection concept based on the application note 

https://www.ti.com/lit/an/snoa987a/snoa987a.pdf

They have a very short 1µs pulse signal and are not able to get reasonable simulation results.

I tried to simulate this concept, but it is not working for the PWM 304Hz and shortest PWM=1uS

I am getting negative voltage output

Kind regards

Dierk Bronner | Senior FAE Automotive

  • 0
    TI__Guru 66241 points

    Hi Dierk,

    Dierk Bronner said:
    They have a very short 1µs pulse signal and are not able to get reasonable simulation results.

    The snoa987a.pdf application note is designed for transient current response <10usec, where OPA388 has BW at approx. 10MHz. 

    For overcurrent detection concept and simulation, you would need BW > 100MHz op amp in order to sense <1usec pulse using the similar detection scheme. The max. PRAMPS  products are limited to 50MHz. I think that you may have to go to HS op amp team for support. 

    You may simulate voltage or current pulses from the simulated example below. 

     

    PWM Voltage Pulse 04252024.TSC

    If you have other questions, please let me know. 

    Best,

    Raymond

  • 0
    Prodigy 20 points

    Hello Raymond, correct me if i am wrong...

    Which meansOPA388Q1 can't be used for short pulses<10uS? confirm me please ,,,,in that case in over current detection example <10uS transisent pulses given here is not correct with opa388q1? document https://www.ti.com/lit/an/snoa987a/snoa987a.pdf. we should use any other differential amplifier which is high bandwidth?also i tried to simulate TLV3201 as a ideal comparator...still i am getting negative voltage 

  • 0 in reply to Raymond Zhang1
    Prodigy 20 points

    Hello Raymond, correct me if i am wrong...

    Which meansOPA388Q1 can't be used for short pulses<10uS? confirm me please ,,,,in that case in over current detection example <10uS transisent pulses given here is not correct with opa388q1? document https://www.ti.com/lit/an/snoa987a/snoa987a.pdf. we should use any other differential amplifier which is high bandwidth?

    Also i tried to simulate TLV3201 as a ideal comparator still it is not working

  • 0 in reply to PRIYADHARSINI SUDHARSANAN
    TI__Guru 66241 points

    Hi ,

    The comparator is able to detector the pulse rate, because of the comparator. 

    However, OPA388 does have the BW to detector < 1usec voltage pulse as shown in the simulation below. 

    OPA388 Detecting Ipulse BW 04292024.TSC

    Please specify how the overcurrent pulse is occurred at the Rsense analog front end. The application note is a bit misleading. The simulation is shown that the nominal current is approx. 0.8A, below the threshold of 1A, When the "overcurrent" exceeds 1A (not pulse, rather a step function), then the overcurrent detection is able to response <10usec. 

    If the nominal current is 0A and current pulse is over 1A, then the simulation will get different response time. So it is not clear what your current pulses look like. Thus, it depends how the current pulse amplitudes and the nominal current (PWM average current) looks like in your application.  Below is the simulation from the app. note. 

    OPA388 + TLV3201 It 10usec app note 04292024.TSC

    If you are talking about fast current pulse at Rsens detection, you may have to submit the query to the HS Op Amp Team.

    Best,

    Raymond