Hello I am attempting to make a battery charger based off the TI LM5175EVM-HP board. I am attempting to use this so I can charge a 12V lead acid battery off a variable input. My power source is going to be variable but capable of approximately 4V - 16V. need to be able to charge the battery at up to 20A.
I have already changed the board so it has a higher switching frequency ( about 300 kHz), lowered UVLO ( set to 4V now), changed my output voltage ( set to 13.8V), and changed the sense resistors to be able to accommodate the higher currents. So far everything is working ok when I am supplying a voltage on the top half of my range but it isn't working correctly at the low end.
Any suggestions on how to make this work? I think the issues at the low end are related to VCC maybe being to low for the mosfets.
Is there a different mosfet you know of i could replace these with to help?
Is it possible to supply the power to turn on the fets from the battery i would be charging since even when it is drained it will have a pretty high voltage and then use the incoming power from supply to still charge the battery? Sorry just throwing out ideas.
Any help is appreciated