Can TL431 be used as a bias transistor??

[Leolabs]

Since that TL431 does have low impedance characteristics,wonder can it be used as a bias transistor in a power amp???

 

[Ouroboros]

I use a TL431 (with a capacitor to bypass it) as the bias voltage source in my MOSFET-output current-dumping amplifier.

Don't forget that the minimum voltage produced is 2.5V, so it may not be useful in a bipolar-output amp, and also that the voltage doesn't vary with temperature, so it might not be appropriate for use in many cases.

 

[Corax]

I've done it with success at my "Alexander current feedback amplifier" with IGBTs (of type GT20D101 and GT20D201). The application can be found here:
http://www.analog.com/static/import...tes/58052492001115525484056221917334AN211.pdf

I finally replaced Q14/Q15 and Q16/Q17 also with a TL431, but had to increase the values of C1 and C2 to 47µF - otherwise the TL431 tends to oscillate.

After all it works just fine.

 

[lumanauw]

Nelson Pass use it in one of his Firstwatt amplifier

 

[jaycee]

It's used in Giovanni Stochino's fast MOSFET power amp, with 4 diode connected BD139's for temperature sensing.

 

[lineup]

Nelson Pass use it in one of his Firstwatt amplifier

In Firstwatt F4.
TL431 is used as a precision VBE multiplier.
As F4 works in Class A the insensitiveness to temp. is not a problem.
In Class A temperarture compensation can be less of a problem.
Usually after warm up for some time, the bias will stay very constant.