Good day.My project uses Vin 9 ... 28 V. Lead acid battery 6 cells .. Charge current 5 A. Load current 10A.I am faced with the problem of strong heating of the coil with a load of more than 3 A, the coil heats up> 70 degrees. The coil used is such a SRP1770C-4R7M. All mosfet Sir664.
Could it be caused by incorrect compensation work? And can I calculate the denominations of the compensation components for the LTC4020 in the LTPowerCAD program using a project for example for the LTC3780, how true will this be?
I tried to change the ratings of the parts, the voltage does not jump at the ITH terminal, but the coil still heats up with a load of 3 Amperes. Please help me identify my problem. The operating frequency is set to 100 kHz, the resistor is 261 kOhm.
I increased the frequency to 250 kHz, put in a PQ2614BLA-6R8K choke and changed the compensation circuit. The situation has improved a little, but the throttle still continues to warm up at 10 amperes. On the oscillogram, the choke current, I do not like ripple, what could be the problem?
I can study this further. (I do not like the inductor-current ripple either.) Can you post a schematic of your circuit? See the attachment which describes how best to attach your schematic.
I don't use R56, only R2 is set to 0.010.
L1 - PQ2614BLA-6R8K
Thank you for posting the schematic. I have some comments on the circuit.
For the compensation I suggest you try these values for the compensation at VC.
If you still have problems, please send oscilloscope pictures of SW1, SW2, inductor current. A horizontal sweep of 1µs/division is a good setting to analyze the waveforms.
LTC4020 RNG_SS Control_gbcomp.asc