dc1977a-a DC1977A-A LTC4121EUD-4.2 Demo Board | 400mA Sync Buck Li-Ion Battery Charger, VIN = 4.4V to 40V Demonstration circuit 1977A is the demonstration board for LTC4121EUD-4.2/LTC4121EUD, a 400mA Synchronous Buck Battery Charger. The DC1977A supports the Maximum Power Point Tracking (MPPT) feature on the LTC4121EUD, for use with Photovoltaic (PV) cells or highly resistive sources. DC1977A-A