Typical operating characteristics (continued) – Rainbow Electronics MAX1885 User Manual
Page 14
MAX1778/MAX1880–MAX1885
Quad-Output TFT LCD DC-DC
Converters with Buffer
14
______________________________________________________________________________________
2.45
2.47
2.49
2.51
2.53
2.55
2.5
3.5
3.0
4.0
4.5
5.0
5.5
MAX1778 toc33
V
IN
(V)
V
LDO
(V)
LINEAR-REGULATOR OUTPUT VOLTAGE
vs. INPUT VOLTAGE
(EXTERNAL LINEAR REGULATOR)
I
LDO
= 0
I
LDO
= 750mA
FIGURE 7
2.55
2.45
0.1
1
10
100
1000
2.47
MAX1778 toc34
I
LDO
(mA)
V
LDO
(V)
2.49
2.51
2.53
LINEAR-REGULATOR OUTPUT VOLTAGE
vs. LOAD CURRENT
(EXTERNAL LINEAR REGULATOR)
FIGURE 7
MAX1778 toc35
B
A
2.45V
250mA
2.55V
50mA
2.50V
100
µs/div
EXTERNAL LINEAR-REGULATOR
LOAD-TRANSIENT RESPONSE
A. I
LDO
= 50mA TO 250mA, 200mA/div
B. V
LDO
= 2.5V, 50mV/div
FIGURE 7
MAX1778 toc36
C
B
A
0.5A
0
2.5V
7.8V
8.0V
1A
10
µs/div
EXTERNAL LINEAR-REGULATOR
RIPPLE REJECTION
A. V
LDO
= 2.5V, I
LDO
= 200mA, 10mV/div
B. V
MAIN
= V
SUPL
= 8V, 200mV/div
C. I
MAIN
= 0 TO 750mA, 500mA/div
FIGURE 7
-2.5
-1.5
-0.5
1.5
0.5
2.5
0
2
4
6
8
10
12
14
MAX1778 toc37
V
CM
(V)
∆
V
OS
(mV)
INPUT OFFSET VOLTAGE DEVIATION
vs. COMMON-MODE VOLTAGE
V
SUPB
= 4.5V
V
SUPB
= 13V
-1.0
-0.6
-0.2
0.2
0.6
1.0
4
8
6
10
12
14
MAX1778 toc38
V
SUPB
(V)
∆
V
OS
(mV)
INPUT OFFSET VOLTAGE DEVIATION
vs. BUFFER SUPPLY VOLTAGE
V
CM
= V
SUPB
/ 2
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V
IN
= +3.3V, SHDN = IN, V
MAIN
= V
SUPP
= V
SUPN
= V
SUPB
= V
SUPL
= 8V, BUF- = BUFOUT,
BUF+ = FLTSET = TGND = PGND = GND, T
A
= +25°C.)