Typical operating characteristics (continued) – Rainbow Electronics MAX1779 User Manual
Page 6
4.0
µs/div
RIPPLE WAVEFORMS
MAX1779-14
A. V
MAIN
= 5V, I
MAIN
= 100mA, 10mV/div
B. V
NEG
= -8V, I
NEG
= 1mA, 5mV/div
C. V
POS
= 12V, I
POS
= 1mA, 5mV/div,
FIGURE 5
5V
12V
-8V
A
B
C
100
µs/div
LOAD TRANSIENT
(L = 10
µH, 500µs PULSE)
MAX1779-15
A. V
MAIN
= 5V, 50mV/div
B. V
MAIN
= 5mA to 50mA, 25mA/div
FIGURE 6
5.0V
0
4.9V
A
B
5.1V
50mA
MAX1779
Low-Power Triple-Output TFT LCD DC-DC
Converter
6
_______________________________________________________________________________________
Typical Operating Characteristics (continued)
(Circuit of Figure 5, V
IN
= +3.3V, T
A
= +25°C, unless otherwise noted.)
11.64
11.76
12.00
11.88
12.12
12.24
0
10
5
15
20
25
30
POSITIVE CHARGE-PUMP OUTPUT VOLTAGE
vs. LOAD CURRENT
MAX1779-10
I
POS
(mA)
V
POS
(V)
V
SUPP
= +7V
V
SUPP
= +6V
V
SUPP
= +5V
30
50
40
70
60
90
80
100
0
10
15
5
20
25
30
POSITIVE CHARGE-PUMP EFFICIENCY
vs. LOAD CURRENT
MAX1779-11
I
POS
(mA)
V
POS
(V)
V
SUPP
= +5V
V
SUPP
= +6V
V
SUPP
= +7V
V
POS
= +12V
200
220
240
260
280
300
2.5
3.5
3.0
4.0
4.5
5.0
SWITCHING FREQUENCY
vs. INPUT VOLTAGE
MAX1779-12
INPUT VOLTAGE (V)
SWITCHING FREQUENCY (kHz)
1.244
1.248
1.246
1.252
1.250
1.254
1.256
0
20
10
30
40
50
REFERENCE VOLTAGE
vs. REFERENCE LOAD CURRENT
MAX1779-13
I
REF
(
µA)
V
REF
(V)
50
60
70
80
90
100
0
100
50
150
200
250
EFFICIENCY vs. LOAD CURRENT
(BOOST CONVERTER AND CHARGE PUMPS)
MAX1779-07
I
MAIN
(mA)
EFFICIENCY (%)
V
MAIN
= +5V
TWO-STAGE
CHARGE PUMPS
V
MAIN
= +10V
SINGLE-STAGE
CHARGE PUMPS
V
NEG
= -8V, I
NEG
= 1mA
V
POS
= +12V, I
POS
= 1mA
-8.08
-8.04
-8.00
-7.96
-7.92
-7.88
-7.84
-7.80
-7.76
0
5
10
15
20
NEGATIVE CHARGE-PUMP OUTPUT VOLTAGE
vs. LOAD CURRENT
MAX1779-08
I
NEG
(mA)
V
NEG
(V)
V
SUPN
= +5V
V
SUPN
= +6V
V
SUPN
= +7V
30
50
40
70
60
90
80
100
NEGATIVE CHARGE-PUMP EFFICIENCY
vs. LOAD CURRENT
MAX1779-09
I
NEG
(mA)
EFFICIENCY (%)
0
5
10
15
20
V
SUPN
= +5V
V
NEG
= -8V
V
SUPN
= +6V
V
SUPN
= +7V