Hello!
So I wanted to design a driver for my laser diodes and flashlight LEDs up to 4A. I found this "LED2001PHR" ic and it seemed very convincing until I tried it out. I copied the circuit from ST EdesignSuite (https://www.st.com/content/st_com/en/support/resources/edesign.html):
I created my PCB using EasyEDA because it is easy-to-use and offers free shipping on the first order. Here is my schematic:
And I created a PCB design using this schematic:
And the bottom layer:
My main goals are small size (10*15mm) and the 4A maximum output current.
I can set the output current with the R_S resistor (Iout = 100mV/R_S). I tried to make the ground lines as thick as possible to minimize the trace resistance around the sense resistor (by my calculations it is around 3.5mΩ). I ordered every possible combination of inductors and capacitors to be able to build the most efficient circuit for every LEDs from 1A to 4A. If I put a 30mΩ resistor, the resulting resistance considering the PCB trace resistance is ~33.5, and the output is 3A. I tried 4 other R_S values and I always got the correct Iout by using the 100mV/(R_S+3.5mΩ) formula.
So basically it works great until I cross 3A. If I put a 22, 25, 27mΩ sense resistor the whole thing stopped working. I use my adjustable power supply to test the circuit, with the 30mΩ resistor, the current consumption was 1-1.1A on 15V (I used a 5V, 3A diode) and if I put the 27 or 25mΩ resistor and set the current limit to 4.3A, the consumption is 4.3A on 6.5V (5V 4A diode). I tried to set the current limit to 5A, then the whole thing burned. First I thought that the Chinese supplier sent some trash sense resistors, so I ordered 22, 25 and 27mΩ resistors from a local store and the results were the same. I also considered that they accidentally sent me LED2000 ICs (similar to LED2001 with 3A maximum output current), but the label clearly says LED2k1.
I destroyed 10 ICs now, so I have no idea what to do.
So, my question is: does anybody know what am I missing here?
Thanks in advance
So I wanted to design a driver for my laser diodes and flashlight LEDs up to 4A. I found this "LED2001PHR" ic and it seemed very convincing until I tried it out. I copied the circuit from ST EdesignSuite (https://www.st.com/content/st_com/en/support/resources/edesign.html):
I created my PCB using EasyEDA because it is easy-to-use and offers free shipping on the first order. Here is my schematic:
And I created a PCB design using this schematic:
And the bottom layer:
My main goals are small size (10*15mm) and the 4A maximum output current.
I can set the output current with the R_S resistor (Iout = 100mV/R_S). I tried to make the ground lines as thick as possible to minimize the trace resistance around the sense resistor (by my calculations it is around 3.5mΩ). I ordered every possible combination of inductors and capacitors to be able to build the most efficient circuit for every LEDs from 1A to 4A. If I put a 30mΩ resistor, the resulting resistance considering the PCB trace resistance is ~33.5, and the output is 3A. I tried 4 other R_S values and I always got the correct Iout by using the 100mV/(R_S+3.5mΩ) formula.
So basically it works great until I cross 3A. If I put a 22, 25, 27mΩ sense resistor the whole thing stopped working. I use my adjustable power supply to test the circuit, with the 30mΩ resistor, the current consumption was 1-1.1A on 15V (I used a 5V, 3A diode) and if I put the 27 or 25mΩ resistor and set the current limit to 4.3A, the consumption is 4.3A on 6.5V (5V 4A diode). I tried to set the current limit to 5A, then the whole thing burned. First I thought that the Chinese supplier sent some trash sense resistors, so I ordered 22, 25 and 27mΩ resistors from a local store and the results were the same. I also considered that they accidentally sent me LED2000 ICs (similar to LED2001 with 3A maximum output current), but the label clearly says LED2k1.
I destroyed 10 ICs now, so I have no idea what to do.
So, my question is: does anybody know what am I missing here?
Thanks in advance
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