5V to 12V level convertion ?

Other Hardware General Electronics
1

Hi !

For my project based on an Arduino Mega 2560, i intend to use one (or more) of this peristaltic pump.
It runs at 12VDC (current: 200-300mA).
I would like to use the 5V pin of the Arduino to provide power to the pump, and i would like to avoid the use of an external power supply...
That's why i'd like to elevate 5V to 12V.
Is there a way to do it (components) ? Do you think it is do-able ?

Regards

2

There's no way to use a pin to drive the pump. Even in an ideal world, 200 mA at 12V = 480 mA at 5V, and there's no way a single pin could do that.

You could use a pin to switch a FET / relay, though. Then you could use a boost converter to raise the supply voltage from 5V to 12V - they're available commercially or you could make one:

It might be easier to start with a 12V supply and regulate it down to 5V for the Arduino instead.

3

ok to drive a FET/relay or maybe something like this ULN2803: 8 Channel Darlington Driver (Solenoid/Unipolar Stepper) [ULN2803A] : ID 970 : $3.95 : Adafruit Industries, Unique & fun DIY electronics and kits beacuse i intend to use more than one pump...but where are my 12V ? =( =(

4

but where are my 12V ?

They would be in the power supply that you buy, or scrounge.

5

kris92:
ok to drive a FET/relay or maybe something like this ULN2803: 8 Channel Darlington Driver (Solenoid/Unipolar Stepper) [ULN2803A] : ID 970 : Adafruit Industries, Unique & fun DIY electronics and kits beacuse i intend to use more than one pump...but where are my 12V ? =( =(

You could use the 2803 to drive relays, but fets are smaller, more reliable, and can be driven directly by the Arduino output. Choose "logic-level" fets so that the 5V from the Arduino can swtich the fet fully on, minimising any heat generated when current flows through it.

Paul

6

well ok...but i don't want a 5V power supply for the Arduino and a 12V power supply for each pump !! what an embedded system it will be :stuck_out_tongue:
Maybe we can consider the problem from the other side :
just one external 12V power supply, cutting wires, derivating one way to a 12V to 5V level down to power the arduino, and other way to power my pump with 12V.
Seems crazy ?

edit : sorry Paul, you answered while i was writing this post.
Ok for fets, but will i need an external power supply using fets ?

7

No, starting from a 12V supply and regulating down to 7.5V for the Arduino barrel jack, or 5V to the power header pin, is definitely the way to go.
Than Arduino can control transistors to switch pumps on & off.

8

Bob, why not feed 12V direct to the Arduino barrel connector?

9

is definitely the way to go.

I think you mean "definitely NOT" :slight_smile:

10

Bob, why not feed 12V direct to the Arduino barrel connector?

regarding the specs of the Mega seems possible :
Input Voltage (recommended) 7-12V

11

If the Arduino has much connected to it, the regulator can get quite warm.
I'd rather power the barrel jack from a lower voltage, or bypass the regulator altogether and power the 5V directly.

So starting with a 12V supply is definitely the way to go kris92.
Use a little switching regulator to make 5V and keep things cool:

12

For the fets, one thats often used is IRL520, but that's probably overkill. Something in a TO-92 package?

The other usual recommendaton is 10K to pull the gate low while the Arduino starts up.

13

Which version of IRL520?
Not a bad choice, can find parts with much lower Rds tho.

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