# 5V (3 to 5A) switcher regulator (single chip) exist?

#### GopherT

Joined Nov 23, 2012
8,012
Does anyone know of a stand-alone chip (no external inductor or diode required). Essentially the same as a 7805 linear but much less heat with switching setup.

Input is 8.4v lithium battery to the regulator and output 5V of 2 to 3 amps.

TO-220 or smaller package is preferred.

#### #12

Joined Nov 30, 2010
18,210
I have one that's good for half an amp, but its a small circuit board with the inductor and control chip soldered on it. It plugs into a place for a 7805, but it doesn't have the current you need and it isn't a single chip in a TO-220 package. I believe it is impossible to, "print" enough inductor on silicon to do what you asked for. Maybe there's a way to do it in PWM, but I haven't seen one.

#### crutschow

Joined Mar 14, 2008
25,121

#### crutschow

Joined Mar 14, 2008
25,121
It's able to get buy with a small inductor in the package since the PWM switching voltage is 2MHz and the required inductance value is inversely proportional to the switching frequency..

#### AnalogKid

Joined Aug 1, 2013
8,487
If the only problem with the original 7805 circuit is output current capability, what about adding 2 resistors and going with an LM350? No inductors expressed or implied, same mounting, and the heat load is exactly the same as what you have now with the 7805.

ak

#### GopherT

Joined Nov 23, 2012
8,012
If the only problem with the original 7805 circuit is output current capability, what about adding 2 resistors and going with an LM350? No inductors expressed or implied, same mounting, and the heat load is exactly the same as what you have now with the 7805.

ak
Thank you! I completely forgot about the LM350 as a 3-pin TO-220 package. Sometimes I get knee deep in a problem and reasonable solutions are forgotten (especially with a panicked teacher and disappointed students looking over my shoulder). I just checked - I have two of the old TO-3 tin can packages and a nice unused TO-220 package buried in my parts boxes. The motors were re-routed to non-regulated last night (easy). The LM7805 was still overheating after about 45 seconds and causing some problems. Anyhow, I think a few resistors can be hung directly on the LM350 and the part can be inserted at a 90-degree angle to swap the output and adj pins in positions 2 and 3 (pin 3 (Adj) inserted in the middle position) - at least that is how envision it could fit onto the board for now.

Thanks again.

#### cmartinez

Joined Jan 17, 2007
7,010
FWIW, I've been using these for years. There are also 1 and 2 amp versions out there, for your consideration.

EDIT: hey... I think I might have just posted something useful... finally

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#### crutschow

Joined Mar 14, 2008
25,121
I thought you wanted a switching regulator.
A higher current linear regulator won't affect the heat problem.

#### GopherT

Joined Nov 23, 2012
8,012
I thought you wanted a switching regulator.
A higher current linear regulator won't affect the heat problem.
I do not have a thermometer so I was not sure if the issue was over temp or over current. Hopefully it was over current and the 3A capabilities of the LM350 will take care of it. If not, it is a heat issue and we are back to the option of removing regulation for more of the project, or a switcher.

#### crutschow

Joined Mar 14, 2008
25,121
I do not have a thermometer so I was not sure if the issue was over temp or over current. Hopefully it was over current and the 3A capabilities of the LM350 will take care of it. If not, it is a heat issue and we are back to the option of removing regulation for more of the project, or a switcher.
The current limit in the LM78XX series works instantly.
If it takes 45s to limit the current, then it's a heat problem, not a current problem.