| Electronics > Beginners |
| Controlling led strip with a uC |
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| 24ariel3:
Hi, I want to control a 12V 100mA led strip with a microcontroller, what is the best way to do it, darlington transistor, MOSFET or other way? Thanks |
| macboy:
NPN transistor: emitter to ground, collector to the - side of the LED strip. LED strip + connected to 12 V supply +. Connect 1 kOhm resistor from micro output pin to NPN base pin. Output high = LED On. 12 V and micro (5 V?) must have their ground (-) connected together. Use any 'jellybean' NPN like 2N2222, 2N3904, BC547, any of them can handle 100 mA when saturated. |
| 24ariel3:
What about voltage drop over the npn, won't it make the led strip abit dimmer? (The uC is 3.3V) |
| macboy:
Drop will be equal to VCE(sat) at 100 mA, which should be around 0.35 V. If that is a problem, then you can replace the NPN with a small logic-level N-channel MOSFET, as long as the output voltage of the micro is higher than the turn-on threshold of the MOSFET, and keep the RDSON low (like < 1 ohm) to minimize voltage drop. Something like BSH103 would work. They cost more than a simple NPN, and its a SMT part. |
| 24ariel3:
Mosfet sound good. What about SSR or is it an overkill? When to consider to use SSR? |
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