Demonstration circuit 1887 is a DC/DC supercapacitor buck-boost charger and balancer converter featuring the LTC3128. The DC1887A operates over 1.72V to 5.5V input and charges the output up to 5.5V. Also, the LTC3128 has 2% precision input current limit, which allows the circuit to operate effectively with current limited input power sources like the USB. The 1.2MHz switching frequency operation results in a small and efficient circuit. The converter provides high output voltage accuracy (typically ±2%) over a 1.72V to 5.5V input. The demonstration circuit can be easily modified to generate different output voltages.