The BQ2057 is an advanced linear charge controller for single or two-cell Li-Ion or Li-Pol applications. Figure 10-1 shows the schematic of charger using a PNP pass transistor. Figure 10-2 is an operational state diagram, and Figure 10-3 is a typical charge profile. Figure 10-4 shows the schematic of a charger using P-channel MOSFET.

Figure 10-1 Low Dropout Single- or Two-Cell Li-Ion/Li-Pol Charger

Figure 10-2 Operation Flowchart

Figure 10-3 Typical Charge Profile