MAX1779 Maxim, MAX1779 Datasheet - Page 6

• Manufacturer Part Number: MAX1779
• Description: Low-Power Triple-Output TFT LCD DC-DC Converter
• Manufacturer: Maxim

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