Reference about LDO without any off-chip compensation

[Analog_starter]

Hi all,

Who can give me some reference about a low dropout voltage regulator structure with internal compensation? And it will be stable under any load conditions.

Thanks a lot !!!

Analog_starter

 

[electronrancher]

I think Rincon-Mora wrote a paper about a simple cap multiplier he used on a pmos LDO for internal comp. It's probably NOT unconditionally stable, although it is probably stable for any output load with a given output cap. Generally, the LDO only uses a large output cap for compensation, and you keep your intermal poles high enough so they don't cause a phase shift at the heaviest load when Rout seem the smallest and load pole is highest.

 

[sunking]

Message is unavailable.

 

[huojinsi]

For LDO regulator,it need external compensation,and it can not be stable under any load conditions! u may look for keyword "LDO compensation" in Google.

 

[jinxingsun]

IEEE,JSSC,2003.10.a capacitor-free cmos low-dropout regulator with damping-factor-control frequency compensation

 

[Analog_starter]

Hi jinxingsun,

But this structure is not stable under small load current case if there is no output capacitance compensation, is it right?

Regards
Analog_starter

 

[jinxingsun]

Hi Analog_starter
I simulatated that circuit a long time ago! I find the DFC has a important effect on stability when the load current is very small!You are right. I think we must change the structure of DFC to have a large Miller cap. In the situation of small output current,the complex poles will destry the stability of circuit,and the zeros which is used to cancel the poles don't have much effect .
One of the capfree product is Philips's SA57000-XX. U can look for its data in google!
Thank U !

 

[Analog_starter]

Hi jinxingsun,

That is just a datasheet, not detail structure description. Any more
information about this?

Thanks & Regards
Analog_starter