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LM7480-Q1: System Inrush Current

Ömer K.

Prodigy 225 points

Part Number: LM7480-Q1

Hello,

According to my calculation, I limited the inrush current of the MOSFET (Q1) at the input to approximately 0.173A, but I see that it draws 0.381A when the system is first energized. Is this because of the current drawn by the charge pump? Or does this current also pass through the mosfet? What is the reason why it draws 0.381A?

best regards

over 1 year ago

0 Ömer K. over 1 year ago

Prodigy 225 points

Also, there are 5-10mA spikes on the power line, do you know the reason for this?

0 Rakesh over 1 year ago in reply to Ömer K.

TI__Guru** 106201 points

Hi Omer,

Thanks for reaching out!

We are back from local holidays. we will go through this thread and get back to you soon.

Best Regards,

Rakesh

0 Shiven Dhir over 1 year ago

TI__Guru 52305 points

Hi Omer,

Can you short R1(10k) and test again.

We suspect that added Inrush current is due to the path shown below.

By doing this, Cvs will charge before HGATE turning on and Inrush wont show on top of value you calculated.

Thanks and Regards

Shiven Dhir

0 Shiven Dhir over 1 year ago in reply to Ömer K.

TI__Guru 52305 points

Hi Omer

Please share charge pump behavior also with current

Thanks and Regards

Shiven Dhir