Hello all,
I found a puzzling question lately in our project recently,
In the datasheet from TI, we can use TL431 as follows without connecting feedback resistor from output to input:
My question is what's the range of Von at the output?(In datasheet it says just around 2V).
How can it be set to around 2V when there's no negative free back from the output?
Please try help, thank you very much!
Best wishes,
Junwen
Hello Ronald,
Thank you very much for your reply.
But there's another question for this kind of usage as you said that we must limit the Iref in order the meet the specification.
Of course, this was the recommendation for the third test circuit in datasheet. I think the bottle neck of max current is due to the reliability of internal PN junction of transistor.(not causing too much voltage drift..)
Could you also help find the max current or the leakage current curve for this application also?
Best Regards,
Junwen Yuan
Junwen,
With input up to 2.5V, the input current is less than 4uA. For higher input voltage, current must be limited to less than 10mA. R[min] = (Vin - 2.5V) / 10mA. However it is best to use a lower maximum input current (<2mA).
