Charge pump regulator, when Vin is larger tha Vout ?

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ahgu

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charge pump regulator

REG71055

it says input range is 1.8v to 5.5v for Vout=5.5v
I wonder what if the input is larger than 5.5v? will that still work for charge pump regulator? What will be the characteristics for chage pump regulator when vin is larger than Vout?

thanks
ahgu
 

Re: charge pump regulator

it can work.
use pmos as switch.
if vin>vout, it work as a regulator in linear mode
 

Re: charge pump regulator

I have to put a pmos? or it is already in there?
 

Re: charge pump regulator

Hi
I find some CMOS charge_pump usually use Vin=2.7~5 Vo=5.5v
Io=100ma .. why have 2.7v limit ??

and if I want to design 1.2v -> 5.5v Io=100ma , how large size pmos
switch will be use ? (assume cmos 5v 0.5um process )
someone tell me pmos need large reduce Rds_on ..
but I use (20/0.5 )* 20 cmos switch
I find Vo have limit when vin=2.5 vo=4.4 not 5v
 

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