Voltage regulator question?

[curry87]

Hi looking for some advice im looking for a 5v dc voltage regulator which has < .5v dropout and can supply >= 200 ma ?


I was thinking of using 2x le50cz each can supply 100ma so two in parallel will get me 200 ma would this work?


thanks

 

[Reloadron]

I would look to a solution similar to this rather than trying o parallel regulators. Less adding components to parallel regulators bad things have a way of happening. Each voltage regulator, though nominally rated at the same voltage, will in practice output a slightly different voltage. This tiny difference in voltage has the disastrous consequence of making the regulator with the lowest output voltage trying to carry all of the current. This will cause it's internal thermal protection to trigger (as the regulator overheats) effectively removing that regulator from the circuit and kicking off a chain reaction up through the remaining parallel-connected regulators. Everything gets ugly real quick. While this problem can be overcome by adding more components my choice would be a regulator along the lines of what I have linked to.

Just My Take
Ron

 

[duffy]

^ Yes, there are some odd things that do not work in parallel the way you might expect - regulators, leds, transformers, etc. You can parallel batteries because of an odd thing with the internal resistance (it increases as it goes flat) but with regulators one will wind up trying to supply all the current while the other does nothing.

 

[curry87]

Would running a voltage regulator up to say 80-90% of its total safe output current 24 hours 7 days a week be pushing it ?

thx

 

[duffy]

^ No, they are rated for less than they can really do.

 

[Reloadron]

With proper heat sinking and installation the chip is designed and built to run at its rated current. It is designed and built to do so 24/7/365 so while running a component like a voltage regulator below its maximum ratings is a nice to have, it is not a requirment. During design phase I personally like to keep components below 75 to 80% of their ratings but is it a requirement? Nope.

Ron

 

[alec_t]

You could build a reg from discrete components if you're feeling masochistic. The attached simulated circuit has a drop-out of ~ 40mV at 1A load current.

 

[bountyhunter]

Hi looking for some advice im looking for a 5v dc voltage regulator which has < .5v dropout and can supply >= 200 ma ?

You can easily build one with the LP2975 controller. Paralleling linears is a pain.

 

[Mr RB]

There are plenty of low dropout 5v 500mA regulators in SMD packs, I like the SOT-223 pack as it has 0.1" pin spacing and you can easily use it in stripboard or a breadboard.