Z
zenerbjt
Guest
Do you agree the attached schematic for the VOD207T opto is in error. The pullup resistor in the collector is too low value.
The VOD207T has a CTR of 100-200
However, fig 6, page 5 of the datasheet shows that when Vce=0.4V, then CTR could be as low as 0.55.
In the attached, I(diode) = 8.1mA
..therefore i(collector) can be a maximum of only 4.45mA. As such, V(collector) could be as high as 1.21V…..this is above the logic low threshold of the 3V3 fed micro.
https://www.mouser.co.uk/datasheet/2/427/vod205t-1767048.pdf
The VOD207T has a CTR of 100-200
However, fig 6, page 5 of the datasheet shows that when Vce=0.4V, then CTR could be as low as 0.55.
In the attached, I(diode) = 8.1mA
..therefore i(collector) can be a maximum of only 4.45mA. As such, V(collector) could be as high as 1.21V…..this is above the logic low threshold of the 3V3 fed micro.
https://www.mouser.co.uk/datasheet/2/427/vod205t-1767048.pdf