The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Design >> Analog Design >> comparison of two LDO structures !!
https://designers-guide.org/forum/YaBB.pl?num=1223434027

Message started by pllneil on Oct 7^th, 2008, 7:47pm

Title: comparison of two LDO structures !!
Post by pllneil on Oct 7^th, 2008, 7:47pm

Hi,all
I am designing a LDO with required output voltage of 3V and current ability of 50mA. There are two structure to choose ,
but i don't know what merit each has.
what difference are between them,and which is better?
Thanks in advance.

[img][/img]

Title: Re: comparison of two LDO structures !!
Post by Tlaloc on Oct 7^th, 2008, 9:48pm

These are identical structures, just with different flavors of inputs. Either one could be made to meet the specs that you've given, but there are so many trade-offs implied in your question. To answer the question as you stated it, but with a large amount of ambiguity, both have merit and both could be better at different times depending on the circumstance.

It really seems like you need to consult a text book first, and one popular one is "Analysis and Design of Analog Integrated Circuits" by Grey, Hurst, Lewis, and Meyer.

Title: Re: comparison of two LDO structures !!
Post by thechopper on Oct 12^th, 2008, 9:16am

The only difference between the two structures is the error amplifier used for the loop. As Tlaloc pointed out there are several trade offs usually invovled that should be considered when it comes to decide for the error amplifier's topolgy, that your question cannot be answered without more information about your circuit requirements.

Regards
Tosei