[SOLVED] 12V/13V Switching Power Supply Design

[sole_developer]

I have though about making a power supply (Variable), switch for either 12V or 13V (some chips need 12V!)........The LM317.bmp LM317 structure, the one I have designed is in the pdf....Could you please help me with your experiance whether or not what I have designed will work...

THanks in advance!

(PS: I used the voltage calculator on LM317 Voltage Calculator - Electric Circuit)

PS: the '+13/+12' pin will be the output based on position of the switch PWR.

View attachment LM317.bmp
View attachment POWER BOARD.pdf

 

[kalbun]

One comment: from your board I see you have an input voltage of 15V. Did you check the datasheet to verify if the regulator can still work with only 2V of differential voltage?
Be careful because there are a lot of LM317 from several manufacturers, so you have to check exactly the type you intend to use.

 

[sole_developer]

From what I read online on the voltage regulator page is that you need the input to be 1.8v greate than the output......Other than what you have mentioned, can I make the board as I have shown it, will it have good stability...or do I need to add zener diodes or seomthing to improve that....!??? Or is it ok as it is ..... i have added resistors in series to get the correct vlaue for the resistors........And I was planning on using Tantalum Capacitors and a resistors of wattage 1/2......is that OK!??

Thank in advance

 

[kalbun]

If you want to be reasonably sure that everything works, I higly recommend you to simulate your circuit.
You can download LTSpice for free, and in less than one day you should be able to grab the essential elements to perform a simulation. Moreover you can find online models for many real-worlds devices, so that the simulation becomes very accurate.
The ability of using a simulator is a great plus for an engineer.

 

[mishra12]

12V/13V Switching Power Supply Design using micro controller ?

 

[kalbun]

hmm... I see your point. Well, let assume it's a power supply for a 12-V microcontroller 8O
But yes, sole_developer should move to the right forum

 

[sole_developer]

Yes actually it is a power supply for a Microcontroller....12V/13V switching power supply......I guess I should have posted in the other FORUM!! Thanks again guys!

 

[sahu]

Yes actually it is a power supply for a Microcontroller....12V/13V switching power supply......I guess I should have posted in the other FORUM!! Thanks again guys!

i think it is usefull for u

 

[memarian]

I have though about making a power supply (Variable), switch for either 12V or 13V (some chips need 12V!)........The LM317.bmp LM317 structure, the one I have designed is in the pdf....Could you please help me with your experiance whether or not what I have designed will work...

THanks in advance!

(PS: I used the voltage calculator on LM317 Voltage Calculator - Electric Circuit)

PS: the '+13/+12' pin will be the output based on position of the switch PWR.

View attachment 50408
View attachment 50409

Hi,

1) LM317 isn't a switching regulator , it's a linear regulator.

2) as kabun mentioned it , check your specific device datasheet ,for voltage difference at your maximum current. (in Linear regualtors , the minimum voltage difference that the device needs between input-output is variable with load current.)

3) add a 100uF Capacitor between the input pin and Ground. also increase the capacitor in output pin (25uF) to something like 47uF and add a 100nF ceramic capacitor in parallel with it. (both on output pin)

4) your capacitors should be as close as possible to regualtor pins.

Good Luck!

 

[sole_developer]

OK....actually, I have added a swtich, the LM317 can regulate voltage based on the two resistors (i have the datasheet attached), so when the switch is in one position, the correspoinding resistor values are connected...if it is in another position, likewise...........So, I have done the modifications like u told me (LM317-02.bmp)......Thank u again

 

[memarian]

Hi,

Everything is seems fine. but be careful, according to dropout voltage diagram, you will be fine until you keep your load current under 500mA . (Typical dropout voltage that regulator needs ,will be under 2V-also some chips aren't Typical) , but according to tables if you want full accuracy(Reference voltage) you should have at least 3V voltage difference between input & output. so at 13V maybe your circuit doesn't work as expected (0.1..0.2V lower or higher) with 15V input.if your load current is low <100mA, i think that you won't see any issue, this type of behavior usually appears in higher loads.

Good Luck!

 

[sole_developer]

Well, I am using this for a PIC Programmer ( I have developed one), and I don't think it will consume more than 100mA......most of the uC only consume <=50mA during programming.....so considering the LEDs and what not, I don't think the comsumption will be more than 100mA....but anyways.....you have made a very good point, and I will increase the input voltage.....

Thank You again........
(if you are interested I can also show you the PIC Programmer I have made...it uses an external power supply.)

 

[sole_developer]

I have not built the design yet, but thank you for everything........one more thing.....what do they call a course where you learn how to make stuff out of metal...(you know, like small boxes, frames.....out of metal or even carbon fiber, etc)....and I have been working with Orcad to try and simulate some circuits...its a pain to learn it....anyone know any good books/tutorials.........

Thanks in Advance

 

[memarian]

I have not built the design yet, but thank you for everything........one more thing.....what do they call a course where you learn how to make stuff out of metal...(you know, like small boxes, frames.....out of metal or even carbon fiber, etc)....and I have been working with Orcad to try and simulate some circuits...its a pain to learn it....anyone know any good books/tutorials.........

Thanks in Advance

Hi,

About that Course : I don't know about it.

About Orcad : If i remember correctly in Orcad 10.x , in Help Menu there was simple Learning Course with 15~16 Basic Lessons. (at least i saw it in Orcad Capture & Orcad Layout-Currently i don't have Orcad to verify)

I also used Orcad Manuals .In your Orcad start Menu, there is Online Manual Link, if you installed them on your HDD or Having your Installation Disk,there will be no problem (loading from Local Drive).as I remember ,in these Manuals (PDF Versions) they explain everything with Examples (that you can see them in your Installation folder/Example Directory). These Documents are the best Manuals that i saw for Orcad IMO.

Good Luck!

 

[sole_developer]

Thank u again for everything guys..........