help with current from PIC

[rina_1220]

Hey all. I'm working on a project in which I need to control 2 leds from a PIC. The only problem is that one of the leds needs 120mA, and the other 60mA for the project to work fine. But PIC only can provide 25mA per port.
How would I do that, considering that my spacing limits are very restrict? I mean, i cannot use so many components and the components i chose must be small. any ideas on how to do solve this problem?

 

[IanP]

Then you have to use external current "boosters" ..
You may consider 2N7000-series mosfets (SOT-23) for this job (no gate resistors required) .. https://www.fairchildsemi.com/ds/2N/2N7000.pdf

Regards,
IanP

 

[rina_1220]

that'd be a good choice. But these transistors are really hard to find in my town. I'd prefer to work with something in which the components would be easier to find.
Any other suggestion, please?

 

[nguyennam]

You should use the bipolar transistor instead of a MOSFET, it must be every where. A n-p-n (2N2222 in TO-92 or SMD package must be OK) or p-n-p (2N2907 in TO-92 or SMD) choice depends on your circuit: the LED connected directly to the + terminal or to the - terminal of the power supply.

You will need 2 more resistors, 1 for the base circuit of the transistor and connected to the PIC output pin, 1 for the collector circuit in series with the LED.

nguyennam