Battery Charger and Step-Down
Converter for Portable Applications
Typical Characteristics – Battery Charger
Constant Charging Current
vs. Set Resistor Values
1000
600
500
AAT2556
Charging Current vs. Battery Voltage
(V
ADP
= 5V)
R
SET
= 3.24kΩ
I
CH
(mA)
I
CH
(mA)
100
400
300
200
100
R
SET
= 5.62kΩ
R
SET
= 8.06kΩ
R
SET
= 16.2kΩ
R
SET
= 31.6kΩ
10
1
1
10
100
1000
0
2.7
2.9
3.1
3.3
3.5
3.7
3.9
4.1
4.3
R
SET
(kΩ)
Ω
V
BAT
(V)
End of Charge Battery Voltage
vs. Supply Voltage
4.206
End of Charge Voltage Regulation
vs. Temperature
(R
SET
= 8.06kΩ)
Ω
4.23
4.204
R
SET
= 8.06kΩ
V
BAT_EOC
(V)
6.5
4.22
4.21
4.20
4.19
4.18
V
BAT_EOC
(V)
4.202
4.200
4.198
4.196
4.194
R
SET
= 31.6kΩ
4.5
4.75
5
5.25
5.5
5.75
6
6.25
4.17
-50
-25
0
25
50
75
100
V
ADP
(V)
Temperature (°C)
Constant Charging Current vs.
Supply Voltage
(R
SET
= 8.06kΩ)
Ω
220
210
Constant Charging Current vs. Temperature
(R
SET
= 8.06kΩ)
Ω
210
208
I
CH
(mA)
200
190
180
170
I
CH
(mA)
6.5
V
BAT
= 3.3V
V
BAT
= 4V
205
203
200
198
195
193
190
V
BAT
= 3.6V
4
4.25
4.5
4.75
5
5.25
5.5
5.75
6
6.25
-50
-25
0
25
50
75
100
V
ADP
(V)
Temperature (°C)
2556.2006.05.1.0
9