# LM317 Voltage Regulator

I want to regulate a voltage suppose 60 V, but I only have an LM317 (or any similar voltage regulator IC) with voltage regulation range of 30 V max.

Is there any way I can use a combination of two or more LM317s to make a voltage regulator that can regulate 60 V (or more)?

Can I feed the positive output of one LM317 as ground in the 2nd LM317, and measure the voltage between the output of the 2nd LM317 and ground of the 1st LM317?

I do not have any particular use or reason to ask this question. I am just curious if I can do that. This is just a hypothetical situation.

• No, use something rated for 60 volt input. Commented Mar 20, 2021 at 22:25
• Indeed no, I also think you need to educate yourself on how to do voltage regulation and what it means. For example: is that 60 V input or output voltage? What is the load current? Why 60 V? First get some experience with those LM317 below 30 V. Commented Mar 20, 2021 at 22:32
• How much you want output voltage range? As each LM317 goes up to about 40V differential voltage, they could be arranged to drop down from 60V down. Commented Mar 20, 2021 at 22:34
• Does this answer your question? Variable power supply 200V Commented Mar 21, 2021 at 12:48
• Hm, I wrote a rather lengthy answer to your 200 V variable power supply question. All the same things still apply to 60 V; is it possible that either your accuracy requirements back then were totally out of proportion, or you're really just looking for an easy solution to a hard problem? Commented Mar 21, 2021 at 12:49

Any way? Yes there is. But if you require high currents they will get very hot:

Image source: Figure 15: Tracking Preregulator Circuit from Texas Instruments LM317 datasheet

This is suggested by the TI datasheet. You can also use a BJT or MOSFET with a Zener to replace the first one by a simpler tracking regulator.

• The tracking regulator will blow if the output is adjusted to a low value with a 60 V input. Commented Mar 20, 2021 at 23:39

The LM317 is, in normal operation, only limited to 30V across its terminals, and that does not, technically, mean that it cannot regulate a 60V output, given 70V input; after all, there's no grounded pin on the IC. That's only ten volts applied to the LM317.

This is not recommended, however, because the LM317 is not completely protected in such a situation against an output short, or other transient situations that may occur on startup.

Yes you could, but suboptimal. Have you thought about searching distributor stock on specs? Do this 1st next time and define ALL your specs 1st! DIRTFT(Do It Right The First Time).!

Can you use a TL783 with a heatsink? We aren’t supposed to do shopping for you.

• I mentioned clearly i want to use lm317 only!! Commented Mar 22, 2021 at 15:50