Compact, High-Efficiency, Dual-Output
Step-Up and LCD Bias DC-DC Converter
MAX1677
Typical Operating Characteristics
(Circuits of Figures 2 and 3, T
A
= +25°C, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
(V
OUT
= 3.3V)
MAX1677-01
EFFICIENCY vs. LOAD CURRENT
(V
OUT
= 5V)
MAX1677-02
MAXIMUM LOAD CURRENT
vs. BATTERY INPUT VOLTAGE
(PWM MODE)
MAX1677-03
100
PFM MODE
A = V
IN
= 2.4V
B = V
IN
= 1.2V
90
EFFICIENCY (%)
A
C
100
D
A
700
600
LOAD CURENT (mA)
500
400
300
200
100
0
V
OUT
= 3.3V
V
OUT
= 5V
80
EFFICIENCY (%)
E
F
60
80
B
D
B
40
C
PWM MODE
A: V
IN
= 3.6V
B: V
IN
= 2.4V
C: V
IN
= 1.2V
PFM MODE
D: V
IN
= 3.6V
E: V
IN
= 2.4V
F: V
IN
= 1.2V
70
PWM MODE
C = 2.4V
D = 1.2V
60
0.1
1
10
100
1000
LOAD CURRENT (mA)
20
0
0.1
1
10
100
1000
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
EFFICIENCY vs. LOAD CURRENT
(LCD V
OUT
= 12V)
MAX1677-04
EFFICIENCY vs. LOAD CURRENT
(LCD V
OUT
= 20V)
MAX1677-05
REFERENCE VOLTAGE
vs. REFERENCE CURRENT
MAX1677-06
100
90
EFFICIENCY (%)
80
A
70
60
50
40
0.1
1
10
B
C
CIRCUIT OF FIGURE 2
A: V
IN
= 3.6V
B: V
IN
= 2.4V
C: V
IN
= 1.2V
100
CIRCUIT OF FIGURE 2
A: V
IN
= 3.6V
B: V
IN
= 2.4V
C: V
IN
= 1.2V
1.2550
90
EFFICIENCY (%)
REFERENCE VOLTAGE (V)
100
1.2525
80
A
B
60
C
50
1.2500
70
1.2475
1.2450
0.1
1
10
0
20
40
60
80
100
LOAD CURRENT (mA)
REFERENCE CURRENT (µA)
100
LOAD CURRENT (mA)
LOAD CURRENT
vs. START-UP VOLTAGE
MAX1677-07
NO-LOAD SUPPLY CURRENT vs.
INPUT VOLTAGE (LCD OFF)
MAX1677-08
NO-LOAD SUPPLY CURRENT vs.
INPUT VOLTAGE (LCD ON)
1.0
0.9
SUPPLY CURRENT (mA)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
V
OUT
= 3.3V
PFM MODE
V
LCD
= -20V
MAX1677-09
450
400
350
LOAD CURRENT (mA)
300
250
200
150
100
50
0
0
0.5
1.0
1.5
2.0
2.5
PFM
V
OUT
= 3.3V
TESTED WITH
RESISTIVE LOAD
0.20
0.18
0.16
SUPPLY CURRENT (mA)
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0
V
OUT
= 3.3V
PFM MODE
LCD OFF
1.1
PWM
3.0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
START-UP VOLTAGE (V)
INPUT VOTAGE (V)
INPUT VOLTAGE (V)
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5
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
