Hi everyone,
I've created a simple board that uses a fixed output 3.3V TPS63001 switch mode regulator. According to the datasheet, I've chosen a 2.8A shielded wire-wound inductor (TDK SPM-LR Series Type 3015 Shielded Wire-wound SMD Inductor with a Metal Core, 2.2 μH Wire-Wound 2.8A Idc, RS Australia stock number 123-3132), input capacitors are 10uF and 100nF, output ones are two 10uF ones, size is 0805. The issue I'm having is that if I connect even one 6.8Ohm 5W resistor - I'm getting a voltage drop on output of about 300-500mV, if I connect two 6.8Ohm resistor to ramp up current to about 1A - I'm getting only about 3.1V output. Input is connected to a lab power supply set to 3.7V and 1.5A of output. On lab power supply I can see that it stays in CV mode and consumption current is about 0.95A-1.1A. I'm measuring output directly at wires connected to resistor(s). According to TPS63001 datasheet output should stay stable at 3.3V up to 1.2A of current supposing input stays at or above 3.6V. Am I doing something wrong in measuring this or there can be something else? Thanks a lot for your help in advance!
P.S. I don't have an oscilloscope at the moment, but ordered one to see what's going on inductor and output pins. Maybe inductor is not beefy enough? 2.8A should be sufficient though.