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TPS43330-Q1: Quiscent Current and Input transient pulse information

ANIKET
Prodigy 340 points
Part Number: TPS43330-Q1
Other Parts Discussed in Thread: TPS43330A-Q1

Hi,

We are checking the feasibility to use TPS43330 in one of our  requirements. Regarding this IC , I have below query. Could you please provide the below info at the earliest?

1)      Quiescent current when boost and both buck converters are active.

2)      Duration of the input transient pulse up to 60V? Will this device be able to handle the transient pulse of 58V for 300ms?

 

Regards

TPS43330

  • 0
    TI__Genius 16410 points
    Hello,

    Thanks for reaching out to us. I've assigned this post to the appropriate apps engineer, he will respond to your questions.

    Regards,
    Karl
  • 0
    TI__Genius 9310 points

    Hello,

      Your answer to question 1, is not as straight forward as a single value. The LPM quiescent current for the buck converters is about 55uA, and the operating current for the bucks are about 7.6mA. The boost quiescent current however is some what negligible. The controllers quiescent current is already accounted for in the buck quiescent current and when the boost is off there is no switching current.

    The boost will only be active below the input voltage threshold of about 7V. To determine the assumed quiescent current of all of the converters, you have to determine the input voltage and efficiency at that voltage for the boost. Worst case would be around 3V input and assuming 8V out of the boost. The efficiency of the boost will be around 60%. Your boost input current will be about 2.7 times higher than the output in order to step up the voltage, plus the loss due to the efficiency, and you will see an input current about 3.8 times the output current. Take your load (the two buck converters) operating at a no load current of 7.6mA, and the boost will have about 29mA on the input. This does not count the peak switching currents from driving the mosfet, but those currents will be averaged into the input current over time. A good input filter will handle that and won't add up to more than a few milliamps.

    As you can see it's not a simple answer and requires a lot of information to process. Normally you wont be operating over time in this state. The boosts primary function is to supply current during load dumps and other normal car transients that would normally cause a restart of the electronics in the car. However there are a lot of other applications that the TPS43330A-Q1 can operate in.

    Your second question is difficult as well. The TPS43330A-Q1 is rated for a max voltage of 40V. Any voltages over this abs max limit will effectively reduce the life of the part. Yes this part has been tested to ISO standards and specifically Test Pulse 5a. TI can't guarantee proper operations above the abs max limit of 40V, however this part can withstand higher transient voltages. I would recommend adding filters or transient suppressors as needed to protect your system, and most importantly test your system and self certify your design under these conditions. you will feel much more confident in your design if you do.

    I hope this answers your questions. Thank you for using E2E.

      

  • 0 in reply to Gordon Varney
    TI__Prodigy 340 points

    Thanks Gordon.

    My customer has further query as below:

    1. Can the device handle pulse5a at 58V for 300mS? We are using a TVS at the input (to protect the circuits from Pulse5a) whose clamping voltage is 58V. [While the datasheet indicates that the device can handle transient voltage upto 60V, it does not qualify on the duration of the transient voltage]

    Regards

  • 0 in reply to ANIKET
    TI__Genius 9310 points
    I understand your concern and your question. As I pointed out, the ABS max for this part is 40V. Any voltage over ABS max will degrade the life of the part. With that point I will add that the part was tested to ISO Test Pulse 5a but not certified. Please look up the ISO test method to understand the ISO specification for the Test Pulse 5a.
    Remember that any transient over the 40V will have an effect on the life of the part. If you continuously ran Test Pulse 5a over and over at some point the part will cease to function. It is up to the customer to test this part to determine if it can withstand 58V for 300ms. It is also up to the customer to determine how many 58V 300ms transients the part can handle.
    Ti will only verify operations up to 40V as the data sheets specifies. Please work with the customer to complete a self certification program for the stated transient pulse. If the part fails this transient pulse test, then decrease the TVS voltage to a level that will allow the part to tolerate the pulse.