1
\$\begingroup\$

I am working on designing a current source for a LED driver, which can work up to max:16A, as long as stays On less than 500msec. Actually, the leds circutry is a Dome-light which is divided in 4 sectors. The 4 sectors have a common ground and they are trigger in PNP mode(24Vdc) individually.

DOME light, 4 sectors

I am using a current sense-resistor of 10mOhm resistance, between a n-channel mosfet`s source terminal and ground. The voltage measured on the current sense-resistor is feed to a differencial OpAmp which output controls the mosfet´s gate voltage. Nothing new here, it is the simplest current source circuit. I am using a digital rheostat to create a voltage divider which sets the OpAmps reference voltage on the non-inverting terminal: enter image description here Components: - TLV2372IP (Op Amp) - MCP4162 (Digital Rheostat) - STP55NF06L (Mosfet 60V,55A,Rds-On 18mOhm) - Current sense-resistor 10mOhm/0.1% tolerance.

Basic schematic:

schematic

simulate this circuit – Schematic created using CircuitLab

Questions:

  • The circuit drives the current to the leds array with stability. The power supply is a Meanwell DR-120-24/5A. Why can I get 4,6,8 or 15 Amps currents?If the power supply is rated 5 Amps max? (I didn´t have a higher current rated power supply at hand).
  • I found in internet that a N-Channel or P-Channel MOSFET High-Side Drive should be more stable and worth to try. But How? I don´t know how to go about it. Could you give me some ideas, please?

This circuit it is for using the Dome_light for a photometric stereo machine vision application. Actually, I am a machine vision programmer. I am not an electronics engineer, sorry for not giving more information. Thanks in advanced

EDIT:IMPORTANT!

I have said that the circuit drives current with stability. But I know that this low-side driver will be unstabled if there is noise in the power supply or noisy enviroment like in a factory.It works steady only by chance. It is why I will need to change the circuit to work in high-side, I think... Also as you can see, in the real circuit I have used a voltage follower with a second opamp which gives the sense resistor voltage-drop to the differential opamp.

\$\endgroup\$
0
\$\begingroup\$

I have said that the circuit drives current with stability. But I know that this low-side driver will be unstabled if there is noise in the power supply or noisy enviroment like in a factory. It is why I will need to change the circuit to work in high-side, I think... Also as you can see, in the real circuit I have used a voltage follower with a second opamp which gives the sense resistor voltage-drop to the differential opamp.

\$\endgroup\$
  • 1
    \$\begingroup\$ This isn't an answer to your question. Why did you put it in the "Your Answer" box rather than edit into your question? \$\endgroup\$ – Transistor Jun 24 at 19:14
  • \$\begingroup\$ So don't leave it here :-) Instead, please edit the question, add this update wherever it is appropriate into the question (perhaps add it at the end?) and delete this "non-answer" from here ASAP, before a moderator has to delete it for you. Thanks. \$\endgroup\$ – SamGibson Jun 24 at 19:45
  • \$\begingroup\$ Thanks for your suggestions. \$\endgroup\$ – Xabier Fernandez Jun 24 at 20:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.