The LTC3128 is a 1-2 cell supercapacitor charger, similar to the LTC3110, but it has a higher charge current at 3A Vs. 2A. The other primary differences between the LTC3128 and the LTC3110 are: Backup capability is present on LTC3110 only due to its bi-directional architecture, higher minimum supercap charging voltage of 1.8V Vs. 0.1V on LTC3110, and Higher quiescent current. The automatic cell balancer on the LTC3110 is a linear Op-Amp based type Vs. an inductive-based type used on the LTC3128, PowerGood feature is present on the LTC3128 only, slightly higher maximum input/SYS voltage of 5.5V Vs. 5.25V on LTC3110, and slightly larger QFN footprint/package of 4mm x 5mm Vs. 4mm x 4mm for LTC3110.