The design requirements include the following:
- Input supply = 5 V
- Battery is 1-cell
LiFePO4
- Fast charge current:
ICHG = 100 mA
- Charge voltage: VREG =
3.6 V
- Charge safety timer:
tSAFETY: 10 hr
- Termination current:
ITERM = 10% of ICHG or 10 mA
- Precharge current:
IPRECHG = 20% of ICHG or 20 mA
- TS – Battery temperature sense =
10-kΩ NTC (103AT)
- RS = 2.3 kΩ
and RP = 70 kΩ added to modify battery charging temperature
window to: -10ºC to 60ºC
- TS pin can be pulled down to
disable charging