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Transmitter Design

Posted by admin on March 8, 2013

Our transmitter is using the Vishay TSUS5202 IR LED. For best range, we wish to push through the highest current possible; to determine this we check out the data sheet:

current.PNG

 We're driving the transmitter at 38kHz, which means the period is 26us. We run at 50% duty cycle, so pulse duration is 13us. Reading from the 0.5 tp/T line we find If is 300mA.

Supply voltage is 3.3V. From the spec sheet voltage drop is 1.3V; however I have measured at 1.05V. That's at a zero-current state though.

For 300mA, that means we need a current limit resistor at 6.6ohm.