I've not used MOSFETs in circuits before. They look like ideal for what I want to do - PWM control some RGB LEDs.
The LED strips are rated 12V 1.2 Amp (they come pre-soldered, sets of 3 LEDs in a chain with a resistor, on flexible strip).
I'm using a PIC for the software, which I've got a handle on. I've been using just a basic 20mA LED on each pin with a resistor to test, so that's all working. The PIC runs at 5V and can sink 30mA per pin max.
Now I think I need to link MOSFETs to the PIC so it can drive the 1.2A 12V stuff.
I've found a MOSFET that I *think* will meet spec and is low cost - STP16NF06, N-channel MOSFET Transistor 16A 60V, 3-Pin TO-220
http://uk.rs-online.com/web/p/products/486-2206/
Not really understanding them though, I don't know if my thinking is right.
The PIC outputs 5V, which is my "VGS". If I'm reading the graph right, then if I were using a 15V "VDS", I could switch about 9Amp with a "VGS" of 5V. Since I'm only using 12V it would be less, but well over the 1.2A I need, and it looks like it would be about 3A at 4.5V, so even if the PIC output is a little lower I should be fine.
Spec sheet says max 45W power dissipation... well the whole circuit wont use that much (I calc about 15W total) so again I should be fine.
Have I got this right, or am I about to make things go "pop!" ?
The LED strips are rated 12V 1.2 Amp (they come pre-soldered, sets of 3 LEDs in a chain with a resistor, on flexible strip).
I'm using a PIC for the software, which I've got a handle on. I've been using just a basic 20mA LED on each pin with a resistor to test, so that's all working. The PIC runs at 5V and can sink 30mA per pin max.
Now I think I need to link MOSFETs to the PIC so it can drive the 1.2A 12V stuff.
I've found a MOSFET that I *think* will meet spec and is low cost - STP16NF06, N-channel MOSFET Transistor 16A 60V, 3-Pin TO-220
http://uk.rs-online.com/web/p/products/486-2206/
Not really understanding them though, I don't know if my thinking is right.
The PIC outputs 5V, which is my "VGS". If I'm reading the graph right, then if I were using a 15V "VDS", I could switch about 9Amp with a "VGS" of 5V. Since I'm only using 12V it would be less, but well over the 1.2A I need, and it looks like it would be about 3A at 4.5V, so even if the PIC output is a little lower I should be fine.
Spec sheet says max 45W power dissipation... well the whole circuit wont use that much (I calc about 15W total) so again I should be fine.
- The 12V supply goes to the LED + wire.
- The output pin of the PIC goes to the MOSFET G pin, and there should be a 1kohm pull-down resistor to ground.
- The MOSFET D goes to LED - wire.
- The MOSFET S pin is tied to ground.
Have I got this right, or am I about to make things go "pop!" ?