LP5907 – About Output capacitor value & inrush current

Q1: "... Could you please let us know the behavior of device when the output capacitor is 200uF? ..."

A1: There is no characterization information available for LP5907 behaviour with Cout > 10uF. The use of any Cout >10uF is not recomended or encouraged. In any case, please define the 200uF capacitor type (Ceramic, Aluminum, Tantalum, or other). Unknown if there will be any oscillation, but the Load Pole ( 1 / (2 x pi x Cout x (Vout/Iout)) ) will be so low that some aspects of the LP5907 performance will be compromised. Note that there will be no assurance of device operation with Cout >10 uF as this is outside the ensured operating conditions, the customer is on their own.

Q2 : "... They would like to decrease the inrush current of the Figure 5 ..."

A2 : The in-rush current depends on the internal start-up (i.e. rise-time) of the reference voltage circuitry via the EN pin, the Cout value, and the internal current limit. There is no good work-around.

Hi Donald-san,

Thank you for your prompt reply.

Please let me ask an additional question.

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[Q1]

The Cout is the ceramic capacitor and the terms of use are as follows.

<use conditions>

Vin=5.0V

Vout=4.5V

Iout= around 200mA

Cout= around 200uF

How necessary is the load pole?

Please let us know if you have a recommended value.

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[Q2]

Thank you for the information!

I understood that the inrush current does not depend on the input voltage.

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Regards,

Kanemaru

Hi Donald-san,

Could you please let us know the current status?

I would appreciate your reply.

Regards,

Kanemaru

" ... How necessary is the load pole? ..."

No set answer for this. All depends on users expectations and the behavior of the load.