Constant current (10A) buck converter?

[Artlav]

My old nemesis, the Xenon Arc Lamp, we meet again.
You want 8A of constant current at around 17V.
I tried to feed you from 12V by stepping up, but it was foiled again and again, for there ain't such thing as constant current boost converter.
But be afraid, since i now got 24V, and am not afraid to use them...

Ahem.
I'm looking for a simple/modern way of making a constant current regulator, that would take 24V input and provide 8-10A on the output, by stepping the voltage down.
Essentially, a buck converter with current feedback.
I can think of several ways to make it using TL494 with P-MOSFET or IR2125 or similar shenanigans, but maybe there is some neat and common regulator/controller IC nowadays that does just that without the extra complications (like dealing with either 20V gate voltage limit on P-FETs or high side driving of N-FETs)?

[ovnr]

Just look for a somewhat flexible LED driver controller - Linear has a few which are incredibly nice.

On which note: Yes there are constant-current boost converters. A bunch of 'em.

[langwadt]

My old nemesis, the Xenon Arc Lamp, we meet again.
You want 8A of constant current at around 17V.
I tried to feed you from 12V by stepping up, but it was foiled again and again, for there ain't such thing as constant current boost converter.
But be afraid, since i now got 24V, and am not afraid to use them...

Ahem.
I'm looking for a simple/modern way of making a constant current regulator, that would take 24V input and provide 8-10A on the output, by stepping the voltage down.
Essentially, a buck converter with current feedback.
I can think of several ways to make it using TL494 with P-MOSFET or IR2125 or similar shenanigans, but maybe there is some neat and common regulator/controller IC nowadays that does just that without the extra complications (like dealing with either 20V gate voltage limit on P-FETs or high side driving of N-FETs)?

There are plenty of LED drivers that are constant current boost converters

if your load can be floating you can turn a buck upside down and avoid the pfet/highside driving

http://spritesmods.com/rgbledlamp/weirdbuck.png

[Artlav]

On which note: Yes there are constant-current boost converters. A bunch of 'em.

More precisely, i have repeatedly failed to make a constant current boost converter.
http://www.edaboard.com/thread300483.html
https://www.physicsforums.com/threads/boost-converter-switch-node-spiking.716486/page-2#post-4543001
In the end, it is absolutely unstable:
https://www.physicsforums.com/threads/constant-current-boost-converter-problems.749692/

Maybe i just don't know how to make one?

There are plenty of LED drivers that are constant current boost converters

The few i know off ebay have a response time measured in many seconds.
The voltage rise slowly.
It won't drive an arc lamp like that, which goes 1000000000 Ohm to 1 Ohm in 200 nanoseconds upon ignition, give or take a few milliseconds for the output capacitor to discharge.

if your load can be floating you can turn a buck upside down and avoid the pfet/highside driving

That is actually a neat idea.
Feels like it would emit a ton of EMI, however, with the whole reflector assembly being the switching node.

[ovnr]

if your load can be floating you can turn a buck upside down and avoid the pfet/highside driving

http://spritesmods.com/rgbledlamp/weirdbuck.png

Do be warned that that topology generates a shitton of EMI if you have long wires (or any wires at all); after all, the LED cathode is flipping between the input voltage and some intermediary voltage every switching cycle, with a not insignificant amount of current flowing. It's going to be a mess.

[eneuro]

http://spritesmods.com/rgbledlamp/weirdbuck.png

Put in series with inductor a few turns of wire over cut toroid core (or even printed on PCB) with SS495A radiometric hall sensor in the gap and you have galvanic insulated feedback to your MPU ADC to adjust output current and make "software fuse"-when current moveing average from 1ms is above eg. 15A - turn off PWM and help to do not change your cicuit into a few hundreds wats toaster depending on type of failure and how powerfull your PCB tracks and mosfets are 

[langwadt]

if your load can be floating you can turn a buck upside down and avoid the pfet/highside driving

http://spritesmods.com/rgbledlamp/weirdbuck.png

Do be warned that that topology generates a shitton of EMI if you have long wires (or any wires at all); after all, the LED cathode is flipping between the input voltage and some intermediary voltage every switching cycle, with a not insignificant amount of current flowing. It's going to be a mess.

it is no more or less than a regular buck, the switching node is at the transistor not the cathode
it is just referenced to supply instead of ground which in AC terms should be the same

[langwadt]

On which note: Yes there are constant-current boost converters. A bunch of 'em.

More precisely, i have repeatedly failed to make a constant current boost converter.
http://www.edaboard.com/thread300483.html
https://www.physicsforums.com/threads/boost-converter-switch-node-spiking.716486/page-2#post-4543001
In the end, it is absolutely unstable:
https://www.physicsforums.com/threads/constant-current-boost-converter-problems.749692/

Maybe i just don't know how to make one?

There are plenty of LED drivers that are constant current boost converters

The few i know off ebay have a response time measured in many seconds.
The voltage rise slowly.
It won't drive an arc lamp like that, which goes 1000000000 Ohm to 1 Ohm in 200 nanoseconds upon ignition, give or take a few milliseconds for the output capacitor to discharge.

if your load can be floating you can turn a buck upside down and avoid the pfet/highside driving

That is actually a neat idea.
Feels like it would emit a ton of EMI, however, with the whole reflector assembly being the switching node.

a boost is not as stable as a buck

the reflector assembly will not be the switching node, it'll be the output voltage just like a regular buck

[LaserSteve]

See page 34.

http://www.excelitas.com/Downloads/Cermax_Eng_Guide.pdf

Kind of minimalist but it works.

Work hard to keep the ringing ignite pulse out of your circuitry using LC low pass filters!!! If the lamp does not fire the pulse gets reflected into the PSU.

Steve