Today got a message from GTP-bot that TL431 is extremely slow. Not sure it may be good to believe A.I. as it makes mistakes very often, so I started to check a datasheet. Datasheet has two versions, old one to 3 MB and new one for 240 kB. Nor in one, nor in another was no a single word for how fast is TL431. Probably some of You have any hint what to expect? Technically, its not so large job to measure that time of response, but let it stay for the role of last measure if none will have any idea.

 

This slide deck might have some good information.

 

I think this graph is the only hint- from P24 of data sheet

 

Ya`akov. Thanks a lot. Both versions 1K and 6.3K is at least orientating me!
Sensacell! Thanks for that graph also. I read about 50 to 70 usec the shift.

 

Today got a message from GTP-bot that TL431 is extremely slow. Not sure it may be good to believe A.I. as it makes mistakes very often, so I started to check a datasheet. Datasheet has two versions, old one to 3 MB and new one for 240 kB. Nor in one, nor in another was no a single word for how fast is TL431. Probably some of You have any hint what to expect? Technically, its not so large job to measure that time of response, but let it stay for the role of last measure if none will have any idea.

Hi,

"Extremely slow" is a relative term and without a reference it's hard to understand exactly what the chat program was referring to.
To get a better idea, ask it about the LM358 and see if it says the same thing about that. The LM358 would be considered slow compared to the much faster op amps, but would be considered fast compared to some of the chopper stabilized op amps. Asking about other products may give you a better idea of what the silly AI program was meaning.
I've had my problems with it too it doesnt seem to know some of the standard math notation so you will often get very ambiguous math results from it.

That said, i would consider the LM431 to be a bit slow also, and maybe slower than the LM358 even. It all depends on how you intend to use it though.
The dynamic impedance is decently low but starts to go up after about 50kHz, which is considered low by today's standards. At 100kHz it may not be useable for an application that has to be able to regulate faster.

The thing about this product though is that there are other considerations such as the required load capacitance, and since the current would be limited the only way to know if it will work in a given application is to test it. That's because there does not seem to be any data on load capacitance vs speed. In order to get this thing to be stable you may have to add a lot of load capacitance and that will slow it down. A larger capacitance will of course slow it down.
Also, the gain goes down with frequency too so that means the ability to regulate becomes impaired with increasing frequency. That's the same with the LM358 where the 0db gain is around 1MHz and the slew rate is only around 0.5v/us which is considered slow by today's standards. However, this as well as the LM431 are still useable in many applications and work very well if you know how to use them.

If you have a scope i would advise to do a few little tests to see how it responds to various stimuli, such as a quick change in input voltage and a quick change in load current demands. This has to be with several values of load capacitance though with the device working in a stable condition for a given application.

 

I thought that TL431 is a precision voltage reference while LM358 is a dual op-amp.

 

Speed is not usually a critical application characteristic for a precision voltage reference, such as the TL431, unless possibly if it is being used as a voltage-sensitive comparator.

 

I thought that TL431 is a precision voltage reference while LM358 is a dual op-amp.

Hi,

Yes, but the speed issues are similar and that was the point of the question.

Incidentally, there is another IC with both the LM431-type voltage reference and an LM358-like op amp (or two). Nice IC. LM432. It might be discontinued.