Hi,
I have a SMPS circuit where the output voltage is regulated by adjusting the resistance in a voltage divider . The FB pin has a Vref of 0.6V, and it regulates Vout such that FB remains at 0.6V. To adjust the output voltage from 3-9 V, I used a digital potentiometer (MCP4131).
Its come to my attention that D Pots cant handle voltages higher than its supply voltage, which is what I've been noticing on my circuit (around 5.5V for Vout was the max).
I'm trying to find a workaround for this problem, and nothing practical has come to mind (i considered putting the pot on the lower side resistor, but the equation then becomes an inverse function, and as i approach 9V the slightest change in resistance would sway the voltage)
The output voltage equation for this chip is: R2 = R1( (x/0.6) -1 ), x being the desired output voltage, R1 the resistor between Vout and FB, and R2 between FB and GND.
Any suggestions?