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problem on compensation of a LDO?

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ken_cn

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Hi, all
I am designing a LDO. But when I simulated the open loop gain and phase, I found that the dc gain, unity gain frequency and phase margin are different in different loading condition.
How can I deal with it? Could you give me some suggestions?

Thank you!


Ken
2007/08/0.6
 

paley

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yes, dc gain, unity gain frequency and phase margin are different in different loading condition.

because the load res will changed the output pole,and the ESR will add a zero,if your regulator have a large output cap,you must simulation the condition of max output current
 

szekit

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if your load is the second pole, worst case stability is at min output current and max output cap.
 

iamxo

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i think you need to compensate your LDO to insure your LDO will be stable under all load condition!

good luck.
 

edwintsu

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Ken, u can refer to the below patent.

B/R
Edwin
 

txdydhr

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hi, szekit! u say worst case stability is at min output current and max output cap,
why the worst case stability is at these case? could u plz give a detailed commentate, thanks!
 

liuyonggen_1

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put the dominant pole at the output, and consider the worst case, everything is OK
 

lokay

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liuyonggen_1 said:
put the dominant pole at the output, and consider the worst case, everything is OK
But it's hard to do that? How can you achieve?
 

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