high current o/p from 7805 ?

[ful babu]

7805 high current

other than that one is specified in the data sheet of 7805, how abt connecting some 7805s in parellel is it possible to get higher current ?

like below ?

 

[IanP]

high current 7805

This is not a good idea as you never connect independent voltage sources in parallel. The way to avoid this situation would be to use equalizing resistors of, say, 0.1Ω at all three outputs of the 7805s, but you will be loosing good voltage regulation and voltage will fluctuate with the increase or decrease of the drawn current ..
Regards,
IanP

 

[checkmate]

7805 current ratings

If you look at the datasheet for the regulator
http://www.datasheetcatalog.com/datasheets_pdf/L/M/7/8/LM78XX.shtml
Several application circuits exist for using increasing the current output via an external transistor.

 

[Johnson]

7805 high output current

LM7805 is not good for this job, if you need more current it is better to use new LDO devices, like SPX1580. Those are capable foras high as 7A of current!

 

[sysco_stevens]

7805 output current

That's no big problem, because though each 7805 has some different output

voltage, but 7805 has current limiting function, if output current is

less than a 7805's output capacity, then only the 7805 with highest output

voltage provide the output current, when output current become larger,

the 7805 with highest output voltage will go into current limiting state and

decrease output voltage, when the output voltage fall below to some extent,

other 7805 become to conduct and provide extra current.

the result is each 7805 will output different current, and the output voltage

will has some little step when a 7805 become to conduct.

best regards




if output current is large

other than that one is specified in the data sheet of 7805, how abt connecting some 7805s in parellel is it possible to get higher current ?

like below ?

 

[SkyHigh]

7805 current

ful babu,

7805 has many types with S, L, H etc. I think L comes in 100mA and many people choose 78L05, S or H comes in other current rating like 1A or 500mA. You need to check with Fairchild, National, etc because some types might not be in production anymore or the types could be obselete.

You can modify your rectifier circuit such as full-wave rectifier instead of bridge rectifier to double the load current from the supply.

Instead of using 7805 which regulates voltage, not current, try checking LM317 which is a current regulator. Reference circuit designs with LM317 might just give you an idea on how to increase and vary load current.

 

[olemp]

7805 more current

here is a desing idea:

High-current supply uses
standard three-terminal regulator

**broken link removed**

 

[nvd]

datasheets of regulator ic 7805s

Connect one diode at the output of each regulator to protect them from the voltage stress if they differ a little in the output voltage.