3.2 Lithium Battery Charger (U202)

A 4.2V, lithium battery connected to the 2-pin, 2 mm pitch right-angle male battery header can be charged using lithium battery charger (MCP73871-2CC) (U202) from the USB power supply at 100 mA fast charge current.

The battery management circuit automatically handles the selection between the USB power supply and battery supply. The current is shared between charging the battery (if connected) and powering the target application. For more details on the MCP73871 Lithium battery charger, refer to the Stand-Alone System Load Sharing and Li-Ion/Li-Polymer Battery Charge Management Controller Data Sheet (DS20002090).

Table 3-4. Battery Charger Status LED

LED Color

Function
Red (D201)
  • Connected to pin 8 (STAT1)/(LBO) (active low signal) of the MCP73871
  • STAT1 – Charge status indication. The LBO feature indicates when the battery is running low while operating with battery only. Triggered, if the voltage is < 3.1V.
  • The STA1/LBO is also connected to PIC32WM-BZ6204UE (PA3) to signal the battery charge status to the PIC32WM-BZ6204UE Module.

Blue (D203)
  • Connected to pin 6 Power Good (PG) (active low signal) of the MCP73871
  • The PG output is low whenever the input to the MCP73871 is above the Under Voltage Lockout (UVLO) threshold and greater than the battery voltage.

Green (D202)
  • Connected to pin 7 (STAT2) of the MCP73871
  • Indicates when the battery is fully charged