A Simple question for LED frequency
时间：04-06
整理：3721RD
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Hi, everyone
I get an infrared LED named SFH 4550. the datasheet says, it has a raise time 'tr' about 12 ns.
"Switching times, Ιe from 10% to 90% and from 90% to 10%, IF = 100 mA, RL = 50 Ω , tr, tf 12ns"
So, my question is if the forward current is only 1 mA, the frequency or let's say the rise time 'tr' will rise or decrease?
(I did some experiment, it shows when I give the current from 0.5 mA to 8 mA, the rise time is always 6 ns)
Thanks a lot !
I get an infrared LED named SFH 4550. the datasheet says, it has a raise time 'tr' about 12 ns.
"Switching times, Ιe from 10% to 90% and from 90% to 10%, IF = 100 mA, RL = 50 Ω , tr, tf 12ns"
So, my question is if the forward current is only 1 mA, the frequency or let's say the rise time 'tr' will rise or decrease?
(I did some experiment, it shows when I give the current from 0.5 mA to 8 mA, the rise time is always 6 ns)
Thanks a lot !
I think the rise/fall time will be roughly constant provided the load and reverse bias voltage stay the same. If you use 1mA rather than 100mA then you would think the rise time would be 100 times slower, but the signal only has to rise 1/100th of the amount, so you end up with the same actual time from 10% to 90% of your output signal.
Keith