Datasheet

MAX1925/MAX1926
Switch-Mode 1-Cell Li+ Chargers
6 _______________________________________________________________________________________
Typical Operating Characteristics
(Circuit of Figure 1, V
SUPPLY
= 5V, V
BATT
= 4V, T
A
= +25°C, unless otherwise noted.)
CHARGE-CURRENT ACCURACY
vs. SUPPLY VOLTAGE
MAX1925/26 toc01
V
SUPPLY
(V)
CHARGE-CURRENT ACCURACY (%)
11106 7 8 9
-15
-10
-5
0
5
10
15
20
-20
512
V
BATT
= 4V
CHARGE CURRENT
vs. BATTERY VOLTAGE
MAX1925/26 toc02
BATTERY VOLTAGE (V)
CHARGE CURRENT (A)
4.24.03.83.63.43.2
0.2
0.4
0.6
0.8
1.0
1.2
0
3.0 4.4
V
IN
= 12V
V
IN
= 10V
V
IN
= 8V
V
IN
= 5V
SEE THE DROPOUT
BEHAVIOR SECTION
FULL-BATTERY VOLTAGE
vs. SUPPLY VOLTAGE
MAX1925/26 toc03
V
SUPPLY
(V)
FULL-BATTERY VOLTAGE (V)
11105 6 7 8 9
4.196
4.198
4.200
4.202
4.204
4.206
4.208
4.210
4.194
412
SHUTDOWN BATTERY CURRENT
vs. BATTERY VOLTAGE
MAX1925/26 toc04
V
BATT
(V)
SHUTDOWN BATTERY CURRENT (µA)
4.03.83.63.43.2
1.5
2.0
2.5
3.0
3.5
4.0
0
1.0
0.5
3.0 4.2
EFFICIENCY vs. SUPPLY VOLTAGE
MAX1925/26 toc05
V
SUPPLY
(V)
EFFICIENCY (%)
11109876
75
80
85
90
95
100
70
512
V
BATT
= 4V
EFFICIENCY vs. BATTERY VOLTAGE
MAX1925/26 toc06
BATTERY VOLTAGE (V)
EFFICIENCY (%)
4.03.83.2 3.4 3.6
65
70
75
80
85
90
95
100
60
3.0 4.2
V
IN
= 12V
V
IN
= 8V
V
IN
= 5V
SWITCHING FREQUENCY vs. INDUCTANCE
MAX1925/26 toc07
INDUCTANCE (µH)
SWITCHING FREQUENCY (kHz)
10
100
1000
10
1001
V
IN
= 12V
V
IN
= 8V
V
IN
= 5V
V
BATT
= 4V
SWITCHING FREQUENCY vs. R
SENSE
MAX1925/26 toc08
R
SENSE
(Ω)
SWITCHING FREQUENCY (kHz)
0.10
100
1000
10
1.000.01
V
IN
= 12V
V
IN
= 8V
V
IN
= 5V
V
BATT
= 4V
SWITCHING FREQUENCY
vs. SUPPLY VOLTAGE
MAX1925/26 toc09
V
SUPPLY
(V)
SWITCHING FREQUENCY (kHz)
11108 976
50
100
150
200
250
300
350
400
450
500
0
512
V
BATT
= 4V