# Maximum load-current of LDO???

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#### letan

##### Member level 3
How to determine maximum load-current of LDO? Determine maximum load-current with load condition? Because Iload is dependent Rload, if Rload decrease -> Iload increase and vice versa.

Example:
If Iload,max=50mA and Vo=1.8v => Rload=36ohm. But, if Rload decrease -> Iload increase and vice versa.

Who can explain clearly for me?

I am going to design a Dynamic Voltage Detector circuit, i need some paper discuss about this problem. This circuit will detect two voltage level: 5.5v and 3.3v. Who can help me? My LDO and Voltage Detection circuit are on chip.

Thank you very much!

#### letan

##### Member level 3
Please, help me hurry up!!!

I need a shutdown crcuit for my LDO. Who can show me the paper or schematic?
Thanks.

#### spikeyang

##### Member level 5
The Maximu output current of LDO is the largest current it can provide. Normally the LDO is used with an RLoad bigger than it's smallest load.

When the RLoad is smaller, the rated output voltage will not sustain. Output voltage and output current determine the rated output power of the device.

So dont think you can lower the RLoad to what you want it to be. Be careful.

#### sethtalk

##### Member level 3
HI,letan,
in general, we defined Io,max by output voltage variance ,take TPS79301 (TI) as example ,
as it provide 200mA, it ratio ( [Vo,nom-Vo]/[Vo,nom]) increase to 1%,
(see figure 2 in spec.)
(Vo,nom: normal output voltage )
so , TI says the IP can provide max current to 200mA,
if you use the IP and you can tolerate the
ratio to 2%,for example, then you can use it up to
more than 200mA
try to see more IP provider's spec, you learn more form them!!

sethtalk

#### pmr9

##### Junior Member level 2
Hi , max current is that ldo can supply and beyond this ldo's pass transistor may not able to get quiescent I it need for proper operation. So Rload shudnt fall below certain value,if that is the case ur Vo wont maintain at req value.

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