Datasheet

3IN
4IN
6VCC
2STAT1
19STAT2
5PG
7 TTC
16CE
10VSS
13FB
OUT 1
OUT 20
PGND17
PGND18
SNS15
BAT 14
ISET18
ISET29
TS12
VTSB11
V
IN
L
C
TTC
C
IN
C
OUT
R
SNS
0.1W
1.5KW 1.5KW 1.5KW
Charge
DoneAdapter
Present
7.5KW
20KW
9.31KW
442KW
RT1
103AT
Battery
Pack
Pack-
Pack+
0.1 Fm
0.1 Fm
0.1 Fm
0.1 Fm
10 Fm
10 Hm
10 Fm
BQ24105
R
ISET2
R
ISET1
200KW
143KW
RT2
VTSB
OUT
MMBZ18VALT1
D1
bq24100, bq24103, bq24103A
bq24104, bq24105, bq24108, bq24109
bq24113, bq24113A, bq24115
www.ti.com SLUS606O –JUNE 2004–REVISED MARCH 2010
Using bq24105 to Charge the LiFePO
4
Battery
The LiFePO
4
battery has many unique features such as a high thermal runaway temperature, discharge current
capability, and charge current. These special features make it attractive in many applications such as power
tools. The recommended charge voltage is 3.6 V and termination current is 50 mA. Figure 19 shows an
application circuit for charging one cell LiFePO4 using bq24105. The charge voltage is 3.6 V and recharge
voltage is 3.516 V. The fast charging current is set to 1.33 A while the termination current is 50 mA. This circuit
can be easily changed to support two or three cell applications. However, only 84 mV difference between
regulation set point and rechargeable threshold makes it frequently enter into recharge mode when small load
current is applied. This can be solved by lower down the recharge voltage threshold to 200 mV to discharge
more energy from the battery before it enters recharge mode again. See the application report, Using the
bq24105/25 to Charge LiFePO
4
Battery (SLUA443), for additional details. The recharge threshold should be
selected according to real application conditions.
Figure 19. 1-Cell LiFePO4 Application
Copyright © 2004–2010, Texas Instruments Incorporated Submit Documentation Feedback 27
Product Folder Link(s): bq24100 bq24103 bq24103A bq24104 bq24105 bq24108 bq24109 bq24113 bq24113A
bq24115