I've never taken a formal power electronic course and am trying to learn a little bit about boost converters.
I assume there are different boost converter designs based on what you're trying to do, and I believe I understand the basic principle for a simple step up DC-DC converter, however I'm struggling to understand how different variations operate. Specifically, I'm trying to understand how a boost converter that takes varying DC voltage levels and is able to maintain a constant output voltage.
Referring to this Texas Instruments DC-DC boost converter, you will see that it can take an input ranging anywhere from 0.9 - 6V. There are several different converters apart of the TPS6102x family, and I'm specifically interested in the TPS61025 which accepts a 0.9 - 6V input voltage, but will output a constant 3.3V. Other chips in the family allow for variable voltage output in which you can use a resistor divider to 'program' the output voltage.
In my case of using the TPS61025, I will not be using the 'FB' pin since the chip can't be programmed to output a certain voltage.
So getting to my question, when a DC-DC boost converter accepts varying input voltages, can it be assumed that there will always be some kind of internal feedback to maintain that output voltage? If a chip were designed to step up a precise voltage of 1.5V to 3.3V, I would assume that it could be implemented either open loop or closed loop since the chip can make the assumption that it will ONLY have one voltage (1.5V) to ever worry about. However in the case of accepting a wider range of voltage inputs, the chip can make no asssumption.
TLDR: Do DC-DC boost converters that accept a wide voltage range input always rely on internal feedback to maintain a constant voltage output?