eanema
Member level 2
Hi,
I am currently attempting to design a power supply for a battery charger project. I require a constant current in the range of a few amps. I originally intended to use an LM317 but linear regulators get really hot. What I'd like to do is use a switching voltage regulator to create a constant current source.
I found the LT1074 switching regulator (here) that can supply up to 5 amps, and has an input voltage of up to 64v. I expect that if I modify the feedback circuit to represent the current instead of the voltage then I should be able to regulate the current.
I propose to insert a 1 ohm current sense resistor in the output path and measure the voltage across it using an instrumentation amplifier. The gain of the inst. amp will be proportional to the current set point, Gain=2.21v / (Iout * Rsense) The 2.21v is from the error amplifier inside the package. See the attached image
I'm also hoping to power this circuit off of mains voltages using a rectifier bridge. I am wondering if this modification should work or if there is a better option, or a package that is specifically designed for this purpose.
Any and all comments and pointers would be appreciated
I am currently attempting to design a power supply for a battery charger project. I require a constant current in the range of a few amps. I originally intended to use an LM317 but linear regulators get really hot. What I'd like to do is use a switching voltage regulator to create a constant current source.
I found the LT1074 switching regulator (here) that can supply up to 5 amps, and has an input voltage of up to 64v. I expect that if I modify the feedback circuit to represent the current instead of the voltage then I should be able to regulate the current.
I propose to insert a 1 ohm current sense resistor in the output path and measure the voltage across it using an instrumentation amplifier. The gain of the inst. amp will be proportional to the current set point, Gain=2.21v / (Iout * Rsense) The 2.21v is from the error amplifier inside the package. See the attached image
I'm also hoping to power this circuit off of mains voltages using a rectifier bridge. I am wondering if this modification should work or if there is a better option, or a package that is specifically designed for this purpose.
Any and all comments and pointers would be appreciated