high ripple with buck using UC3843

[electrophysics]

Hi,
what is the most general and easily available chip in DIP package for buck converter with external mosfets either synchronous or non synchronous. I have simulated with UC3843 but high ripple at output. the UC3843 circuitry is attached. OR if any one can suggest how to improve ripple issue with UC3843. in actual circuit I may use IR2111 with this chip instead of E source. output voltage +5V and input +12V

 

[atripathi]

What is current ripple in %terms, and how much would you like to reduce it? You may also want to check the it is actually ripple or oscillation?

 

[mtwieg]

If there's a lot of ripple it's probably not the controller's fault. Ripple should just be a function of your switching frequency, duty cycle, and the inductor and capacitor sizing. If you're getting unexpectedly large amounts of ripple then I'd check to make sure your FETs are switching correctly with a decent amount of dead time.

For controllers, there are many available that are designed specifically for buck converters, and have built in bootstapped high side drivers so chips like the IR2111 aren't necessary. I did a quick search and linear tech makes the LTC1149 and LT3845 which both have that feature (including synchronous outputs) and are available in DIP-14.