Category: Hardware
Product Number: MAX17701
Software Version: N/A
I have a new design using the MAX17701 to charge a 500F, 13.5V ultracapacitor string. Due to input power limitations, as the ultracapacitor voltage increases, i decrease the ILIM signal to keep the output power constant. This is important to the design.
When the duty cycle on the inductor gets around 50%, I experience a classic case of subharmonic oscillation. Long pulse then a short pulse. I am running at 350kHz with an input voltage of 24V. The instability occurs around 12.8V, or when Vout/Vin is slightly greater than 50%.
The traditional approach to resolve this problem is slope compensation, but it doesn't appear that the device has this capability. Can you suggest an alternate approach to resolve the problem?
