BD139 - enough to be controlled from the Arduino's 0-5V PWM

Using Arduino General Electronics
1

Simple qn, as though I see the Base-Emitter voltage on the datasheet is 5v, wanted confirmation that it's spec is enough for what I need.

Will the PWM signal from an Arduino be sufficient to switch a BD139 on/off in order to control 0-5V on it's output?

I have a 5V silicone heating pad that I want to control the voltage of. Thanks

2

BD139 is a.......transistor then I take it? (you didnt provide a link to any datasheet)

How much current does it need/take for full saturation of the gate?

3

Hi x197

Apologies, didn't think I needed to add a link to a datasheet. I assumed if people knew what a BD139 was, they may be able to answer the question, and vice versa.

The power rating of the silicone heating pad I have is 4W 5V, so the max current is 800ma.

Edit: ... BD139 Datasheet

4

theMusicMan:
Will the PWM signal from an Arduino be sufficient to switch a BD139 on/off in order to control 0-5V on it's output?

An Arduino can certainly click an NPN transistor.
The BD139 alone may not have enough gain for the 800mA you anticipate.
But you could try.
Better use/spec a MOSFET (a low rDS(on), logic-level MOSFET).

5

Thanks for this, I will have a bash at this tomorrow!

6

theMusicMan:
Simple qn, as though I see the Base-Emitter voltage on the datasheet is 5v

You probably misunderstood.
Vbeo 5volt is the maximum reverse voltage between B and E.
It's in the max ratings (warning) section.
Vbe is 1volt max.

For switching, you need a base current of 1/10 of the collector current. An Arduino pin can't provide 80mA.
A darlington like the TIP120 could be used, but they have a high CE saturation voltage.
A logic mosfet might be the best solution.
Leo..

7

Wawa:
You probably misunderstood.
Vbeo 5volt is the maximum reverse voltage between B and E.
It's in the max ratings (warning) section.
Vbe is 1volt max.

For switching, you need a base current of 1/10 of the collector current. An Arduino pin can't provide 80mA.
A darlington like the TIP120 could be used, but they have a high CE saturation voltage.
A logic mosfet might be the best solution.
Leo..

Thanks Leo!
Yep, need to brush up on my understanding datasheet skills :o

8

You could try a two transistors stage.
BD139: emitter to ground, collector to -load, +Load to (external) supply.
BC547: emitter to BD139 base, collector via 33ohm resistor to Arduino 5volt, base via 1k resitor to Arduino pin.
Leo..