LP5907 Inrush current

" ... LP5907 ... output inrush current ..."

The in-rush current is due the delay time required after the EN pin goes high, for all the internal circuitry, including the current limit circuitry, to power-up and stabilize.

The Isc current limit applies when the device is already fully powered-up, operating normally, and then short is applied to the output.

Your test results appear to be typical/normal behavior for LP5907.

Hi Donald,

Thanks for the reply.
What value is the typical the delay time required after the EN pin goes high to make sure the current limit circuitry to power-up and stabilize?

Does this inrush current damage LP5907?

Thanks.

Prescott

This behavior is not something that has been fully characterized.

Typically, customers are reporting, and I have observed on the LP5907 EVMs, that the in-rush current typically peaks in the range of 30 to 60 microseconds after the EN pin goes high.

There appears to be some variation In this time due to Vin and/or Cout. This has not been fully documented.

The closest ensured specification would be Turn-On time. Not exactly the same

"... Does this inrush current damage LP5907? ..."

No.

The following image is an extreme case, well outside the recommended operating range, but it clearly shows the transition from the momentary in-rush current to the controlled current limit (Isc). The Isc current is held until either the LP5907 Thermal Shutdown is activated, or the output voltage is reached.

Hi Donald,

Thanks for your support.

Customer ask us to provide the Maximum Safe Operating Area of  LP5907 internal MOSFET like below.

Do we have this information? 

Thanks.

Prescott

No, we do have not any chart SOA like this.
The LP5907, like most modern LDO's, have internal active circuitry that will protect the device by limiting the maximum current and/or the maximum junction temperature.
It is the customers responsibility to assure that the maximum input voltage is not exceeded.

Hi Donald,

Customer want to make sure the 10us output inrush current don't damage LP5907.

We want to know the Maximum Ratings of output inrush current.

Thanks.

Prescott

" ... We want to know the Maximum Ratings of output inrush current..."

The LP5907 in-rush current is not a ensured, tested, or characterized, parameter. The in-rush current value depends on Vin at power-up or enable, and the Cout value being charged.

" ... Customer want to make sure the 10us output inrush current don't damage LP5907...."

The in-rush current will NOT damage the LP5907. However, it might pull down the Vin supply momentarily.

See my reply on 08-August above :

      "... Does this inrush current damage LP5907? ..."

      No.