Hi guys, the reason i rite this topic is to ask for some guidance in term of choosing a mosfet or transistor for my perticular set up i have this ic call TLC5940, I know that it is a current sink IC and it is really a great ic. I want to use a Mosfet or a transistor to amplify the current running thru a string of LED maybe you could say im doing an LED Strip around maybe 50 led per strip. My question are : 1) Is it better to use a mosfet or transitor? 2) if mosfet which would be better (N type or P type) or If transistor (PNP or NPN)? 3) I will ofcouse drive the Mosfet or transistor into saturation to reduce heat and lost.
You no this changes the whole ball game these chips can only sink current. But can be done there a appnote that shows how to do this.
To help you we need more info like how much you want to drive the leds, voltage,
Not all mosfet or bj are the same and voltage and load are needed to help you.
1) A MOSFET is a transistor. ( Metal-Oxide–Semiconductor Field-Effect Transistor ) 2) You'd need a P channel if you're using the TLC5940
I ended up using the NDP6020p for my TLC work initially, this ended up being a bit of a pain to drive since I was operating at 12v, so I switched over to a UDN2981 darlington array and that worked pretty well until I blew all my TLCs up :grin:
Yep these chips are nice but there a lot better chips for driving a bunch of leds. That one pin gray scale looks nice and is but it was made for Led arrays not led strings.
is there any way that i could control 4 of this http://www.superbrightleds.com/moreinfo/component-leds/1-watt-rgb-led-130-degree-viewing-angle-43-lumens/637/ while using one of this https://www.sparkfun.com/products/10616 i thought of using the ic alone to supply enough current but as i see the full capability of the ic is only 60mA per pin, what i want is to supply 250mA per led colour
Yes there is I’ll post you something today. You can sink 120 mA with a 5 volt supply
No you don’t want 250mA. This chip gives 120 mA your led is good for 150mA Constant-Current
You can’t drive them at 250mA Constant-Current that’s pulsed 250mA the TLC is pumping of the current to give you a full 120 if you set it for that.
Now if you want more read this http://sonicrobots.com/wp-content/uploads/2012/07/arduino-tlc-5940.png