TLV431 voltage maximums?

[treez]

Hello,
First page of TLV431 datasheet says that Vka can be up to 18V...so why then can it only produce an output voltage up to 6V (as it also says on page 1)?

TLV431 datasheet
https://www.ti.com/lit/ds/symlink/tlv431.pdf

So presumably we are not allowed to have an 19V rail, and then a series resistor down from there to the TLV431 cathode, with the cathode and ref pin tied together?

 

[FvM]

Review the datasheet thoroughly for difference between TLVH431 and TLV431.

 

[treez]

Thanks, I missed that....though I should have said in our application we are using the TLV431 as a 1.24V zener diode...so presumably we can connect it up to 40V via a series resistor.?..as in the attached...

 

[FvM]

Yes. The TLV431 voltage rating isn't needed in this circuit, it only matters for the adjustable configuration.

 

[treez]

Thanks, but do you think that at start up, when its still not really "woken up" yet, it may not be initially drawing current, and the full 40V may get through to the cathode pin, even if just for 100us or so?

 

[ZekeR]

You should be fine. There is an internal feed-forward capacitor inside the chip that begins current conduction before the chip "wakes up," and should prevent excessive voltage overshoot.