General > General Technical Chat
LDO current limiter
(1/5) > >>
--Oz--:
The lm317 is an adjustable linear voltage regulator and typically connected like pic 1.
It can also be connected to provide constant current and works very well and only two components, pic 2.

The LM317 is a 1.5A to-220 part, I want a 1A C.C. circuit, so using a 1.25 ohm resistor works, but it requires 3.3V total dropout voltage across both parts.

I am looking for a dropout voltage of 2.5V max (hopefully lower) at 1A,
something like +/-25mA C.C. regulation,
Vin minimum 5V (hopefully more),
Through hole for dead bug wiring (no pcb),
low cost, low component count, TIA!
fourfathom:
How precise and stable do you need?  A simple two-transistor, two-resistor current limiter can have a sub-1V dropout, but the limiting will be soft and the tempco and precision may be found wanting.
SiliconWizard:
https://www.onsemi.com/products/power-management/linear-regulators-ldo/ncp692
--Oz--:

--- Quote from: fourfathom on August 20, 2022, 01:36:21 am ---How precise and stable do you need?  A simple two-transistor, two-resistor current limiter can have a sub-1V dropout, but the limiting will be soft and the tempco and precision may be found wanting.

--- End quote ---
Good question. I am thinking of +/-25mA of the 1A C.C. mode.
Do you have a link to that circuit?
--Oz--:

--- Quote from: SiliconWizard on August 20, 2022, 02:09:17 am ---https://www.onsemi.com/products/power-management/linear-regulators-ldo/ncp692

--- End quote ---
Looking at the DS, it has current limiting, not really a C.C. mode. I looked for applications for the chip and there is none, just typical C.V. circuit.
And, I plan on this to be dissipating the heat, so a little qfn package is not ideal, plus needs a circuit board, I was thinking through hole and something like to-220 so i can burn some watts (at least 5W or more), I will add to my 1st post. Thanks for the reply.
Navigation
Message Index
Next page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod