Rainbow Electronics MAX8724 - Manual (Page 9)

MAX1908/MAX8724
Low-Cost Multichemistry Battery Chargers
_______________________________________________________________________________________ 9
INDUCTOR
CURRENT
500mA/div
V DCIN
10V/div
V BATT
500mV/div
LINE-TRANSIENT RESPONSE
MAX1908 toc04
10ms/div
ICTL = LDO
VCTL = LDO
ICHARGE = 3A
LINE STEP 18.5V TO 27.5V
-1.0
-0.8
-0.9
-0.6
-0.7
-0.4
-0.5
-0.3
-0.1
-0.2
0
0 2 3 4 1 5 6 7 9 8 10
LDO LOAD REGULATION
MAX1908 toc05
LDO CURRENT (mA)
V
LDO
ERROR (%)
V
LDO
= 5.4V
-0.05
-0.03
-0.04
-0.01
-0.02
0.01
0
0.02
0.04
0.03
0.05
8 12 14 16 10 18 20 22 26 24 28
LDO LINE REGULATION
MAX1908 toc06
V IN (V)
V
LDO
ERROR (%)
I LDO = 0
V LDO = 5.4V
-0.10
-0.07
-0.08
-0.09
-0.06
-0.05
-0.04
-0.03
-0.02
-0.01
0
0 200 100 300 400 500
REF VOLTAGE LOAD REGULATION
MAX1908 toc07
REF CURRENT (µA)
V
REF
ERROR (%)
-0.10
-0.04
-0.06
-0.08
-0.02
0
0.02
0.04
0.06
0.08
0.10
-40 10 -15 35 60 85
REF VOLTAGE ERROR vs. TEMPERATURE
MAX1908 toc08
TEMPERATURE (°C)
V
REF
ERROR (%)
90
0
0.01 10 1 0.1
EFFICIENCY vs. CHARGE CURRENT
30
10
70
50
100
40
20
80
60
MAX1908 toc09
CHARGE CURRENT (A)
EFFICIENCY (%)
V BATT = 16V
V BATT = 8V
V BATT = 12V
0
100
50
250
200
150
300
350
450
400
500
0 4 6 2 8 10 12 14 16 18 20 22
FREQUENCY vs. V IN - V BATT
MAX1908 toc10
(V IN - V BATT ) (V)
FREQUENCY (kHz)
I CHARGE = 3A
VCTL = ICTL = LDO
3 CELLS
4 CELLS
-0.4
-0.1
-0.3
-0.5
0
0.2
0.3
0.4
0.5
0 1 2 3 4
OUTPUT V/I CHARACTERISTICS
MAX1908 toc11
BATT CURRENT (A)
BATT VOLTAGE ERROR (%)
0.1
-0.2
2 CELLS
3 CELLS
4 CELLS
0
0.02
0.01
0.03
0.06
0.07
0.05
0.04
0.08
0 0.2 0.3 0.4 0.5 0.1 0.6 0.7 0.8 0.9 1.0
BATT VOLTAGE ERROR vs. VCTL
MAX1908 toc12
VCTL/REFIN (%)
BATT VOLTAGE ERROR (%)
4 CELLS
REFIN = 3.3V
NO LOAD
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V
DCIN
= 20V, T
A
= +25°C, unless otherwise noted.)