This component is a step up converter. I am confused after reading the datasheet http://www.ti.com/product/TPS61041 . It says adjustable voltage upto 28V. But i am not sure if this can be hooked to a microprocessor. My objective is to feed 5v to tps61041 and get 0-28V in output from it based on microprocessor signal. Is this possible?
It's adjustable by means of the resistor divider used to sense the output voltage and compare to the internal reference. There's no digital interface to adjust the output voltage.
One way to adjust the output voltage via microcontroller is to use a resistor to sum an external voltage (generated by a DAC via the micro) into the FB pin node. This will allow you to shift the voltage up and down by changing the DAC voltage.
Here's an example of how this would look (From Maxim):
Resulting in the following equations:
You could experiment with a PWM DAC instead of an actual DAC to see if you can get the performance you are looking for.
Output voltage in this (and many other) converter is determined by voltage divider around feedback input. There are methods to vary the value of resistor R2
Normally it is done by using a DAC with CURRENT STEERING mode, because the R2 should be a purely resistive element as much as possible, otherwise parasitic capacitance of the DAC IC might break stability of the regulator.
A nice example of I2C-controlled DC-DC converter can be found in MAXIM APP-5058 application note, using DS4432 chip.