RT9945 Datasheet, PDF (26/33 Pages) Richtek Technology Corporation – Power Management ICs for Handheld Device

RT9945
BATTERY CHARGE MANAGEMENT FUNCTION
The RT9945 supports charging of single-cell Li-Ion battery packs. The charge process is executed in three phases: pre-
charge (or preconditioning), constant current and constant voltage. A typical charge profile and flow chart are shown in
Figure 13 & 14.
Precharge
Phase
Programmed
Charge
Current
Fast Charge
Phase
4.2V
Constant
Voltage Phase
&
Standby Phase
Recharge
Phase
4.1V
Recharge
Threshold
1/10 Programmed
Charge Current
2.8V
Precharge
Threshold
Charge
Complete
Figure 13. Typical Charge Profile
UVLO > VIN < OVP
& I²C = ON &VIN >
BATT
YES
NO
Power Off State
PFET = OFF
Any State
if VIN < UVLO or
VIN > OVP or
I²C = OFF or
VIN < BATT
BATT < 4.1V
YES
0.5V < TS < 2.5V
BATT>2.8V
YES
Fast-CHG State
ICHG_fast = 1000mA
@RISET = 1.5kΩ
NO
NO
Pre-CHG State
ICHG_pre = 0.1 x
ICHG_fast
Check Thermal ^NO
Temp.<125°C
Decrease
ICHG_fast
Temp.<125°C
YES
Charge Done State
ICHG = 0A
YES _{ICHG<0.1*ICHG_fast}
NO
Figure 14. Charge Flow Chat
www.richtek.com
26
DS9945-01 April 2011