5V/3.3V or Adjustable, High-Efficiency,
Low-Dropout, Step-Down DC-DC Controllers
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Current-Limit Trip Level
(V+ to CS)
CS Input Current
Switch Maximum On-Time t
ON
(max)
Switch Minimum Off-Time t
OFF
(min)
EXT Rise Time
EXT Fall Time
Maximum Duty Cycle
SYMBOL
V
CS
3V
≤
V+
≤
16V
3V
≤
V+
≤
16V
V+ = 12V
V+ = 12V
C
EXT
= 0.001µF, V+ = 12V
C
EXT
= 0.001µF, V+ = 12V
t
ON
x 100%
t
ON
+ t
OFF
95
24
0.8
32
1.1
25
25
96.5
CONDITIONS
MIN
80
TYP
110
MAX
140
±1
40
1.8
UNITS
mV
µA
µs
µs
ns
ns
%
MAX1649/MAX1651
__________________________________________Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
MAX1649-TOC06
SHUTDOWN CURRENT
vs. TEMPERATURE
MAX1649-TOC05
EXT RISE AND FALL TIMES
vs. TEMPERATURE (1nF)
55
50
t
RISE
& t
FALL
(ns)
C
EXT
= 1nF
MAX1649/51-01
80
78
76
I+ (µA)
V+ = 16V
4.0
3.5
3.0
V+ = 16V
2.5
I+ (µA)
60
45
40
35
30
25
V+ = 5V, t
RISE
74
72
70
V+ = 10V
2.0
1.5
V+ = 8V
1.0
V+ = 5V, t
FALL
V+ = 4V
68
66
-60 -40 -20 0
20 40 60 80 100 120 140
TEMPERATURE (°C)
0.5
V+ = 4V
0
-60 -40 -20 0
20 40 60 80 100 120 140
TEMPERATURE (°C)
V+ = 15V, t
RISE
V+ = 15V, t
FALL
-60 -40 -20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
20
15
EXT RISE AND FALL TIMES
vs. TEMPERATURE (5nF)
MAX1649/51-02
EFFICIENCY
vs. LOAD CURRENT (V
OUT
= 5V)
V
OUT
= 5V
CIRCUIT OF
FIGURE 1
MAX1649/51-A1
220
200
t
RISE
& t
FALL
(ns)
180
160
140
120
100
80
60
40
C
EXT
= 5nF
V+ = 5V, t
RISE
90
EFFICIENCY (%)
80
70
60
50
90
EFFICIENCY (%)
80
70
60
50
40
0.1
V
OUT
= 3.3V
CIRCUIT OF
FIGURE 1
V+ = 5V, t
FALL
V+ = 15V, t
RISE
TOP TO
BOTTOM:
TOP TO
BOTTOM:
V+ = 15V, t
FALL
-60 -40 -20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
V
IN
= 6V
V
IN
= 8V
V
IN
= 10V
V
IN
= 12V
V
IN
= 15V
0.1
1
10
100
1k
LOAD CURRENT (mA)
10k
V
IN
= 4.3V
V
IN
= 5V
V
IN
= 8V
V
IN
= 10V
V
IN
= 12V
V
IN
= 15V
1
10
100
1k
LOAD CURRENT (mA)
10k
40
_______________________________________________________________________________________
3
MAX1649/51-A2
240
100
EFFICIENCY
vs. LOAD CURRENT (V
OUT
= 3.3V)
100
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
