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Original question:

TINA/Spice/LM5022: LM5022 Vin pin is out of control

LM5022: LM5022 Vin pin is out of control

Nikhil Gupta (Product Folder Models)
Mastermind 39210 points
Part Number: LM5022

Customer wants to know the answer to the following question. Please refer to the "Related question" for background

"In reality VIN pin has some current level during soft-start. I need to know this value.

If you can not correct the model then at least discribe the nature of this value for instance for 14V Vin supply.

Regards,
Andrey"

  • 0
    TI__Guru* 78200 points
    Hi Nikhil,
    The major current consumption is in the gate drive, which is supplied by VCC, and which is supplied by VIN through the internal LDO. The gate drive current is Cg x Vcc x Fsw, where Cg is the MOSFET total gate charge. Add about 3.5 to 4mA internal use, then you will get the VIN current during startup.

    Thanks,
    Youhao
  • 0 in reply to Youhao Xi
    Prodigy 70 points
    Hi Youhao,
    is there some current limit for VIN pin.
    For example if Cvcc=10uF, then which maximum current will be for VIN to charge the Cvcc?

    thanks,
    Andrey
  • 0 in reply to Andrey Toropov
    TI__Guru* 78200 points
    There is no VIN input current limit. The Input current is determined by its load: VCC load plus up to 4mA used by other internal circuit, but the VIN pin current may appear to be limited owing to the VCC current limit. Cvcc=10uF sounds big, taking longer time to charge up. We usually recommend 1uF. Please refer to the datasheet Applications Information section.