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Design >> Analog Design >> what is meant by bleed current for an LDO regulator?
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Message started by vamshikrishna on Jul 23^rd, 2009, 8:28am

Title: what is meant by bleed current for an LDO regulator?
Post by vamshikrishna on Jul 23^rd, 2009, 8:28am

thanks
vamshi

Title: Re: what is meant by bleed current for an LDO regulator?
Post by thechopper on Jul 24^th, 2009, 8:41pm

I guess a min current consumption provided by a bleeding resistor beyond the actual load that has to supply the voltage for....if the load is purely capacitive then you need a min load current in order to bias the regulator...

Regards
Tosei

Title: Re: what is meant by bleed current for an LDO regulator?
Post by NeoLearner on Sep 3^rd, 2009, 4:01am

It's most likely a current that flows through the differential input pair but is not mirror to the second stage.
So it's like having a current source in parallel with your current mirror.

Because of the increased current, the input pairs have a bigger gm. Thus, the complete opamp has higher gain.
Because the current is not mirrored, it does not cause an increase in current consumption of the second stage.

Title: Re: what is meant by bleed current for an LDO regulator?
Post by loose-electron on Sep 5^th, 2009, 11:56am

It is the minimum current going out thru the pass transistor with external current load set to zero, while still maintaining a stable system.

This can be internally set (thru a load) or externally required (it varies with the design)

Not to be confused with the ground pin current - wich is all the current to run the internal LDO circuits (bandgap and feeddback control system typically)

Mind you, I dont think there is an ISO or IEEE standard definition here so a vendor may define this a little differently.

Title: Re: what is meant by bleed current for an LDO regulator?
Post by vamshikrishna on Sep 7^th, 2009, 1:16am

Thanks for the replies.