I am making a circuit which has buck converter LM3671 inside: http://www.ti.com/lit/ds/symlink/lm3671.pdf Schematics are attached at the bottom of this post. In real application, power source is 3xAA/AAA batteries which should buck-convert voltage to 3.05V.
Input capacitor: 4.7uF
Output capacitor: 10uF
Inductor: 2.2uH (CDRH2D14NP-2R2NC)
Set output voltage(with resistor feedback network): 3.05V
The problem I am having is that output is always 0.2V lower than the input. It starts at very low voltage(below 2V) and continues up to 5V. At larger voltages, the output is 0.1V lower than the input. That is at the output current of 20mA.
At smaller output currents, the difference between input and output is even smaller.
I tried a lot of things, can not find the source of the problem. I am using suggested schematics from the datasheet and suggested components from it. What needs change so IC stops following voltage?