Driving LEDs from logic output of the DS1620 thermostat

jessica

Hello

I'm a propeller user and I·would like to know please what are the most appropriate mosfet or transistor to use
to drive Leds from the TCOM, TH and TL output of the DS1620 thermometer.

Because if I drive the led directly from the output the DS1620 is overheating and so
as noticed on the appnote I·need a buffer like a mosfet or a darlington to operate the led properly.

I only know a few things about those parts and I don't know the best one to sue.

thanks a lot for your help and excuse me for my english (i live in france)

jessica

Leon

Did you put a current-limiting resistor in series with the LED? You could try a high-brightness LED with a 1k resistor. That should be bright enough and won't provide much of a load.

Leon

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Amateur radio callsign: G1HSM

jessica

Thanks for the advice.

It works fine, the DS1620 is not heating so much but I think I can't escape using a mosfet or a transistor if I want to drive a 12v fan for example ...?
I dont know exactly what kind of precise components to use ?
thanks for help ?

Mike Green

The outputs of the DS1620 will sink 4mA or source 1mA. I suggest you use an NPN Darlington like an MPSA14 or equivalent. This will switch 500mA at up to 30V. You'd want a base resistor of 3.3K to 10K.