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.
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: Components: - TLV2372IP (Op Amp) - MCP4162 (Digital Rheostat) - STP55NF06L (Mosfet 60V,55A,Rds-On 18mOhm) - Current sense-resistor 10mOhm/0.1% tolerance.
- 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
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.