Dual-Output (Positive and Negative),
DC-DC Converter for CCD and LCD
MAX685
Typical Operating Characteristics
(Circuit of Figure 3, V
OUT+
= 15V, V
OUT-
= -7.5V, T
A
= +25°C, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
(POSITIVE OUTPUT LOADED)
MAX685-01
EFFICIENCY vs. LOAD CURRENT
(NEGATIVE OUTPUT LOADED)
MAX685-02
EFFICIENCY vs. LOAD CURRENT
(BOTH OUTPUTS LOADED)
85
80
EFFICIENCY (%)
75
70
65
60
55
50
V
IN
= 5.0V
V
IN
= 3.3V
MAX685-03
90
V
IN
= 5.0V
EFFICIENCY (%)
80
V
IN
= 3.3V
85
V
IN
= 5.0V
80
75
EFFICIENCY (%)
70
65
60
55
V
IN
= 3.3V
90
70
60
0
2
4
6
8
10
LOAD CURRENT (mA)
50
0
1
2
3
4
5
6
7
8
9
10
LOAD CURRENT (mA)
0
2
4
6
8
10
LOAD CURRENT (mA)
NO-LOAD CURRENT vs.
INPUT VOLTAGE
MAX685-04
REFERENCE LOAD REGULATION
MAX685-06
2.0
1.250
NO-LOAD CURRENT (mA)
1.5
REFERENCE VOLTAGE (V)
1.0
1.249
0.5
0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
INPUT VOLTAGE (V)
1.248
0
5
10 15 20 25 30 35 40 45 50
LOAD CURRENT (µA)
LX SWITCHING FREQUENCY
vs. INPUT VOLTAGE
MAX865-07
REFERENCE VOLTAGE
vs. TEMPERATURE
MAX685-13
250
240
OSCILLATOR FREQUENCY (kHz)
230
1.254
1.252
REFERENCE VOLTAGE (V)
1.250
1.248
1.246
1.244
1.242
1.240
V
IN
= 3.3V
V
IN
= 5.0V
220
210
200
190
180
170
160
150
2.7
3.2
3.7
4.2
4.7
5.2
5.7
INPUT VOLTAGE (V)
SYNC = V
DD
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
4
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MAXIM [ MAXIM INTEGRATED PRODUCTS ]
