Rainbow Electronics MAX1748 - Manual (Page 6)

MAX1748
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.)
8
10
18
20
12
16
14
22
24
5 8 7 9 6 10 11 12
MAXIMUM POSITIVE CHARGE-PUMP OUTPUT
VOLTAGE vs. SUPPLY VOLTAGE
MAX1748toc10
V SUPP (V)
V
POS
(V)
I POS = 10mA
V POS = 22V
I POS = 1mA
I POS = 20mA
0.80
0.85
0.90
1.05
1.00
0.95
1.10
1.15
1.20
2.5 3.5 3.0 4.0 4.5 5.0 5.5
SWITCHING FREQUENCY
vs. INPUT VOLTAGE
MAX1748toc11
INPUT VOLTAGE (V)
SWITCHING FREQUENCY (MHz)
MEASURED FROM THE
FALLING EDGE OF LX
V
MAIN
= 10V
I MAIN = 100mA
1.244
1.246
1.250
1.248
1.252
1.254
0 20 15 10 30 25 5 35 40 45 50
REFERENCE VOLTAGE
vs. REFERENCE LOAD CURRENT
MAX1748toc12
I REF ( µA)
V
REF
(V)
V IN = 3.3V
V MAIN
10mV/div
V NEG
10mV/div
V
POS
10mV/div
RIPPLE WAVEFORMS
MAX1748toc13
1 µs/div
V MAIN = 10V, I MAIN = 200mA,
V NEG = -5V, I NEG = 10mA,
V POS = 15V, I POS = 10mA
I MAIN
200mA/div
I LX
500mA/div
V MAIN
200mV/div
LOAD-TRANSIENT RESPONSE
MAX1748 toc14
100 µs/div
V IN = 3.3V, V MAIN = 10V,
R MAIN = 500 Ω TO 50Ω (20mA TO 200mA)
I MAIN
200mA/div
I LX
500mA/div
V
MAIN
200mV/div
LOAD-TRANSIENT RESPONSE
WITHOUT INTEGRATOR
MAX1748toc15
100 µs/div
V IN = 3.3V, V MAIN = 10V, INTG = REF,
R MAIN = 500 Ω TO 50Ω (20mA TO 200mA)
-11
-9
-10
-7
-8
-4
-5
-6
-3
5 8 6 7 9 10 11 12
MAXIMUM NEGATIVE CHARGE-PUMP
OUTPUT VOLTAGE vs. SUPPLY VOLTAGE
MAX1748toc07
V SUPN (V)
V
NEG
(V)
I NEG = 20mA
I NEG = 1mA
I NEG = 10mA
V NEG = -10mA
14.4
14.5
14.6
14.9
15.0
14.7
14.8
15.2
15.1
15.3
0 8 6 10 2 4 12 14 16 18 20
POSITIVE CHARGE-PUMP OUTPUT
VOLTAGE vs. LOAD CURRENT
MAX1748toc08
I
POS
(mA)
V
POS
(V)
V SUPN = 12V
V SUPN = 8V
V SUPN = 10V
40
50
80
60
70
90
100
0 8 6 10 2 4 12 14 16 18 20
POSITIVE CHARGE-PUMP EFFICIENCY
vs. LOAD CURRENT
MAX1748toc09
I
POS
(mA)
EFFICIENCY (%)
V SUPP = 12V
V SUPP = 8V
V SUPP = 10V