Datasheet

EFFICIENCY vs. OUTPUT CURRENT
(V
CC
= V
IN
= 5V)
MAX1951A toc01
OUTPUT CURRENT (A)
EFFICIENCY (%)
1.61.20.80.4
10
20
30
40
50
60
70
80
90
100
0
02.0
V
OUT
= 3.3V V
OUT
= 2.5V
V
OUT
= 1.5V
EFFICIENCY vs. OUTPUT CURRENT
(V
CC
= V
IN
= 3.3V)
MAX1951A toc02
OUTPUT CURRENT (A)
EFFICIENCY (%)
1.61.20.80.4
10
20
30
40
50
60
70
80
90
100
0
02.0
V
OUT
= 2.5V
V
OUT
= 1.8V
V
OUT
= 1.5V
V
OUT
= 1.0V
SWITCHING FREQUENCY
vs. INPUT VOLTAGE
MAX1951A toc03
INPUT VOLTAGE (V)
SWITCHING FREQUENCY (kHz)
5.04.54.03.53.0
925
950
975
1000
1025
1050
900
2.55.5
MAX1951A
1MHz, 2A, 2.6V to 5.5V Input, PWM DC-DC
Step-Down Regulator with Enable
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= V
CC
= V
EN
= 3.3V, V
PGND
= V
GND
= 0V, FB in regulation, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at
T
A
= +25°C.) (Note 3)
PARAMETER CONDITIONS MIN TYP MAX UNITS
LX Current-Sense
Transimpedance
From LX to COMP, V
IN
= 2.6V to 5.5V 0.16 0.24 0.35 Ω
High side 2.2 3.1 4.5
LX Current-Limit Threshold Duty = 100%, V
IN
= 2.6V to 5.5V
Low side -0.3
A
V
LX
= 5.5V 10
LX Leakage Current V
IN
= 5.5V
V
LX
= 0V -10
µA
LX Switching Frequency V
IN
= 2.6V to 5.5V 0.8 0.96 1.1 MHz
LX Maximum Duty Cycle V
COMP
= 1.5V, LX = Hi-Z, V
IN
= 2.6V to 5.5V 100 %
LX Minimum Duty Cycle V
COMP
= 1V, IN = 2.6V to 5.5V 15 %
THERMAL
T
J
rising 165
Thermal Shutdown Threshold When LX starts/stops switching
T
J
falling 155
°C
EN
Enable Low Threshold (V
IL
) 0.8 V
Enable High Threshold (V
IH
) 2.0 V
EN Input Current 1µA
Typical Operating Characteristics
(Typical values are at V
IN
= V
CC
= 5V, V
OUT
= 1.5V, I
OUT
= 1.5A, and T
A
= +25°C, unless otherwise noted. See Figure 2.)
Note 3: Specifications to T
A
= -40°C are guaranteed by design and not production tested.