Hi,
I've been looking at a few opto-coupler datasheet and I've really been struggling with some maker's way of giving me the data. Case in point, let's take the 4n37 (a pretty popular one).
I'm looking at Vishay's datasheet (http://www.vishay.com/docs/81181/4n35.pdf) and they claim that it has a CTR of 100% on the first page. But then if I scroll down to look at the graph of If vs CTR, I see in figure 5 that generally, the CTR won't be > 1.0 (100%) which seems to contradict what I read on the very first page.
What does make sense to me is a graph as it provided by Toshiba for the same part (http://pdf1.alldatasheet.com/datasheet-pdf/view/30834/TOSHIBA/4N37.html). In that diagram, (at-least for 10v) I do see that the CTR ranges from slightly less than 100% to 300%.
I would be surprised if these parts differed that much in spec that I'm assuming that I'm reading these wrong. What's even more puzzling to me is that the freescale part seems to suggest that the opto is actually significantly below 100% in figure 2 (http://pdf1.alldatasheet.com/datasheet-pdf/view/2850/MOTOROLA/4N37.html).
Any help in properly reading these datasheet would be appreciated,
Thanks
I've been looking at a few opto-coupler datasheet and I've really been struggling with some maker's way of giving me the data. Case in point, let's take the 4n37 (a pretty popular one).
I'm looking at Vishay's datasheet (http://www.vishay.com/docs/81181/4n35.pdf) and they claim that it has a CTR of 100% on the first page. But then if I scroll down to look at the graph of If vs CTR, I see in figure 5 that generally, the CTR won't be > 1.0 (100%) which seems to contradict what I read on the very first page.
What does make sense to me is a graph as it provided by Toshiba for the same part (http://pdf1.alldatasheet.com/datasheet-pdf/view/30834/TOSHIBA/4N37.html). In that diagram, (at-least for 10v) I do see that the CTR ranges from slightly less than 100% to 300%.
I would be surprised if these parts differed that much in spec that I'm assuming that I'm reading these wrong. What's even more puzzling to me is that the freescale part seems to suggest that the opto is actually significantly below 100% in figure 2 (http://pdf1.alldatasheet.com/datasheet-pdf/view/2850/MOTOROLA/4N37.html).
Any help in properly reading these datasheet would be appreciated,
Thanks