Datasheet
MAX1649/MAX1651
5V/3.3V or Adjustable, High-Efficiency,
Low-Dropout, Step-Down DC-DC Controllers
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
SYMBOL MIN TYP MAX UNITSCONDITIONS
3V ≤ V+ ≤ 16VCS Input Current ±1 µA
C
EXT
= 0.001µF, V+ = 12VEXT Rise Time 25 ns
C
EXT
= 0.001µF, V+ = 12VEXT Fall Time 25 ns
Current-Limit Trip Level
(V+ to CS)
mVV
CS
3V ≤ V+ ≤ 16V 80 110 140
t
ON
t
ON
+ t
OFF
x 100%
Maximum Duty Cycle 95 96.5 %
80
66
SUPPLY CURRENT vs. TEMPERATURE
68
78
I+ (μA)
76
74
-60 -20 60 140
MAX1649-TOC06
TEMPERATURE (°C)
20 100-40 0 8040 120
72
70
V+ = 10V
V+ = 16V
V+ = 4V
4.0
0
SHUTDOWN CURRENT
vs. TEMPERATURE
0.5
3.5
I+ (μA)
3.0
2.5
-60 -20 60 140
MAX1649-TOC05
TEMPERATURE (°C)
20 100-40 0 8040 120
2.0
1.5
V+ = 8V
V+ = 16V
V+ = 4V
1.0
V+ = 12VSwitch Maximum On-Time 24 32 40 µst
ON
(max)
V+ = 12VSwitch Minimum Off-Time 0.8 1.1 1.8 µst
OFF
(min)
-60 -20 60 140
EXT RISE AND FALL TIMES
vs. TEMPERATURE (1nF)
MAX1649/51-01
TEMPERATURE (°C)
t
RISE
& t
FALL
(ns)
20 100-40 0 8040 120
60
55
50
45
40
35
30
25
20
15
V+ = 15V, t
FALL
V+ = 15V, t
RISE
V+ = 5V, t
FALL
V+ = 5V, t
RISE
C
EXT
= 1nF
1 10 10k
LOAD CURRENT (mA)
EFFICIENCY (%)
100
90
80
70
60
50
40
100 1k
0.1
MAX1649/51-A1
EFFICIENCY
vs. LOAD CURRENT (V
OUT
= 5V)
V
OUT
= 5V
CIRCUIT OF
FIGURE 1
TOP TO
BOTTOM:
V
IN
= 6V
V
IN
= 8V
V
IN
= 10V
V
IN
= 12V
V
IN
= 15V
__________________________________________Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
40
-60 -20 60 140
EXT RISE AND FALL TIMES
vs. TEMPERATURE (5nF)
80
MAX1649/51-02
TEMPERATURE (°C)
t
RISE
& t
FALL
(ns)
20 100-40 0 8040 120
60
100
140
120
160
200
180
240
220
V+ = 15V, t
FALL
V+ = 15V, t
RISE
V+ = 5V, t
FALL
V+ = 5V, t
RISE
C
EXT
= 5nF
1 10 10k
LOAD CURRENT (mA)
EFFICIENCY (%)
100
90
80
70
60
50
40
100 1k
0.1
MAX1649/51-A2
EFFICIENCY
vs. LOAD CURRENT (V
OUT
= 3.3V)
V
OUT
= 3.3V
CIRCUIT OF
FIGURE 1
TOP TO
BOTTOM:
V
IN
= 4.3V
V
IN
= 5V
V
IN
= 8V
V
IN
= 10V
V
IN
= 12V
V
IN
= 15V