How to regulate a negative rail with TL431? - Page 2

andy_c · 4th September 2004, 05:05 AM

Oh, just one more thing. If your load current varies a lot, you should consider using a series regulator like the LM337 instead. The TL431 is great for replacing low-power zener diodes, but your load current might spike to a high value and cause the TL431 to turn off. You haven't said what your application is, so it's hard to say.

JoeBob · 4th September 2004, 06:10 AM

Just regulating the voltage feeding a low power opamp. Never toyed with the TL431, and I thought now would be a good time to try it out.

I don't think that the current draw will spike enough to affect the TL431 (should be rather low) so I hope I'll be fine. Otherwise I can always revert to a series reg, just wanted to try a shunt this time around though

.

Oh, and again, thanks alot for all your help, I'm almost done my board and I'll see how it works soon enough.

Raj1 · 4th September 2004, 08:43 AM

Hi,

I think there was a series of tests on TNT audio with series and shunt regs. In these types of low current apps the shung regs outperformed the series regs, they genrated less noise. So for low current opamps these regs are probably a good bet.

Thanks
Raja

jackinnj · 4th September 2004, 12:56 PM

You can always use the TL431 to drive the base of a PNP or NPN power transistor. Then you don't have to worry (as much)about frying the critter.

Ambient isn't always "ambient" -- as in the case where you put the device in a box with other devices which are heating.

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4th September 2004, 05:05 AM	#11
andy_c Banned Join Date: Apr 2003	Oh, just one more thing. If your load current varies a lot, you should consider using a series regulator like the LM337 instead. The TL431 is great for replacing low-power zener diodes, but your load current might spike to a high value and cause the TL431 to turn off. You haven't said what your application is, so it's hard to say.

4th September 2004, 06:10 AM	#12
JoeBob diyAudio Member Join Date: Nov 2001 Location: Montreal, Canada	Just regulating the voltage feeding a low power opamp. Never toyed with the TL431, and I thought now would be a good time to try it out. I don't think that the current draw will spike enough to affect the TL431 (should be rather low) so I hope I'll be fine. Otherwise I can always revert to a series reg, just wanted to try a shunt this time around though . Oh, and again, thanks alot for all your help, I'm almost done my board and I'll see how it works soon enough.

4th September 2004, 08:43 AM	#13
Raj1 diyAudio Member Join Date: Jan 2003 Location: UK	Hi, I think there was a series of tests on TNT audio with series and shunt regs. In these types of low current apps the shung regs outperformed the series regs, they genrated less noise. So for low current opamps these regs are probably a good bet. Thanks Raja

4th September 2004, 12:56 PM	#14
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	You can always use the TL431 to drive the base of a PNP or NPN power transistor. Then you don't have to worry (as much)about frying the critter. Ambient isn't always "ambient" -- as in the case where you put the device in a box with other devices which are heating.

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