Hi Everyone,I have a quick question. I'm hoping to create a small IR emitter (and detector) board using the Arduino Pro Mini 3.3V 8MHz board driven by a 3V CR2032 coin cell battery. I'm trying to make this as small as possible, which is why I went with the Pro Mini and coin cell battery. However, my concern is the current draw from a typical IR LED. As far as I can tell, this will draw around 50mA from the Arduino... which is more than each pin can handle.
Ok. So, do I even need a transistor circuit? Will the CR2032 not be able to provide enough current (ever) to power a single IR emitter? I only need this first prototype to run for 1 hr max... so I was hoping a small battery could work. Plus, the LED wont be on the whole time (small pulses is all I'll be sending... and not incredibly frequently). I can jump up to a larger power supply if necessary...
Although each I/O port can source more than the test conditions (20mA at VCC = 5V, 10mA at VCC = 3V) under steady state conditions (non-transient), the following must be observed:ATmega48A/PA/88A/PA/168A/PA/328/P:1] The sum of all IOH, for ports C0 - C5, D0- D4, ADC7, RESET should not exceed 150mA.2] The sum of all IOH, for ports B0 - B5, D5 - D7, ADC6, XTAL1, XTAL2 should not exceed 150mA.If IOH exceeds the test condition, VOH may exceed the related specification. Pins are not guaranteed to source current greater than the listed test condition.
Is it right to connect three pins to one output :~(will it not burnt arduino pro mini 3.3v?) and if yes then is that current limiting resistance will run through each pin to output.Please clarify it?
Is it better alternative for transistor to amplify current to IR LED output from arduino?
That's true... a coin cell may not be appropriate... but the form factor will be important here, plus this is just for an initial prototype. I can always jump up to a Lipo or some other battery source if power consumption becomes an issue. But, are there any issues running the transistor breakout board off of 3V? And do you think there will be any clock issues with 8MHz resonator to control a 38KHz blinking IR LED?Thanks,Andy