Datasheet

MAX639/MAX640/MAX653
5V/3.3V/3V/Adjustable, High-Efficiency,
Low I
Q
, Step-Down DC-DC Converters
_______________________________________________________________________________________ 3
__________________________________________Typical Operating Characteristics
(Circuit of Figure 3, internal feedback, L = 100µH, T
A
= +25°C, unless otherwise noted.)
100
50
10µ 100µ 1
EFFICIENCY vs.
OUTPUT CURRENT
60
MAX639-1
OUTPUT CURRENT (A)
EFFICIENCY (%)
70
80
90
1m 10m 100m
L = 100µH
V
+ = 9V
MAX639
MAX640
MAX653
100
50
10µ 100µ
EFFICIENCY vs.
OUTPUT CURRENT
60
MAX639-2
OUTPUT CURRENT (A)
EFFICIENCY (%)
70
80
90
1m 10m
MAX639, V+ = 6V
MAX640, V+ = 4.3V
MAX653, V+ = 4V
100m
L = 470µH
100
50
10µ 100µ
EFFICIENCY vs.
OUTPUT CURRENT
60
MAX639-3
OUTPUT CURRENT (A)
EFFICIENCY (%)
70
80
90
1m 10m
MAX639
MAX640
MAX653
100m
L = 470µH
V+ = 9V
Note 2: Output guaranteed by correlation to measurements of device parameters (i.e., switch on-resistance, on-times, off-times, and
output voltage trip points).
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 9V for the MAX639, V+ = 5V for the MAX640/MAX653, I
LOAD
= 0mA, T
A
= T
MIN
to T
MAX
, typical values are at T
A
= +25°C,
unless otherwise noted.)
PARAMETER
V
0.4 1.2
MIN TYP MAX
mAV
LBO
= 0.4V
UNITS
LBO Leakage Current 0.001 0.1 µAV
LBO
= 11.5V
LBO Delay 25 µs50mV overdrive
2.5
SHDN Threshold
0.80 1.15 2.00 V
SHDN Pull-Up Current
0.10 0.20 0.40
Ω
µA
SHDN = 0V
V
µA
T
A
= +25°C
T
A
= T
MIN
to T
MAX
MAX639
MAX640/MAX653
2.8
LX Switch Leakage
0.003 1.0
30.0
VFB Bias Current 4.0 15.0 nA
VFB Dual-Mode Trip Point
LX Switch On-Resistance
50
0.8 1.5
VFB Threshold
1.26 1.28 1.30
mV
1.24 1.28 1.32
LBI Bias Current 210
LBI Threshold
1.26 1.28 1.30
nA
1.24 1.28 1.32
LBO Sink Current
0.8 2.5
CONDITIONS
V+ = 6V, T
A
= T
MIN
to T
MAX
, MAX639
V+ = 4V, T
A
= T
MIN
to T
MAX
, MAX640/MAX653
V+ = 11.5V, V
LX
= 0V
VFB = 2V
V+ = 9V, T
A
= +25°C, MAX639/MAX640/MAX653
MAX6_ _C
MAX6_ _E/M
V
LBI
= 2V
MAX6_ _C
MAX6_ _E/M