• Resolved

LP38512: inrush current

Guru 19140 points

Part Number: LP38512

Hello,

In the customer, the inrush current is larger than the short protection current for LP3965 and LP38512.
Please see the following conditions as inrush current.
Is this current acceptable?

<LP38512>
Vout=1.8V or 1.0V
Inrush current, about 3.6A, 0.3ms
Continuous current is about 0.1A
There is no voltage drop in output/input of the device.

<LP3965>
Vout=3.3V
Inrush current, about 6.1A, 0.3ms
Continuous current is about 0.1A
There is no voltage drop in output/input of the device.

Best Regards,
Ryuji

  • Hi Ryuji,

    Inrush current is the extra current drawn primarily by the output capacitors when the regulator first turns on. There is a period before the internal current limit engages where inrush current is allowed. If the output capacitors are not fully charged during this period, the current limit will engage and the capacitors will continue to charge at the current limit. If the inrush current is higher than desired you may be able to reduce the output capacitance.

    Very Respectfully,
    Ryan
  • Guru 19140 points

    In reply to Ryan Eslinger:

    Hi Ryan san,

    Thank you for the reply. I understood that there is the delay at the start up for current limit.
    I want to know whether there is no damage to the device even if there is inrush current and whether the specification is guaranteed.

    Best Regards,
    Ryuji
  • In reply to Ryuji:

    Hi Ryuji-san,

    Inrush current is normal and expected; however, we are not able to specify inrush current as the amount of inrush current varies due to application specific conditions (size of output capacitors, load current, etc). Due to the limited duration of inrush current the risk of damage to the IC is low.

    Very Respectfully,
    Ryan