LT1940 Datasheet, PDF (3/20 Pages) Linear Technology – Dual Monolithic 1.4A, 1.1MHz Step-Down Switching Regulator

LT1940
ELECTRICAL CHARACTERISTICS The q denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T_A = 25°C. V_IN = 5V, V_BOOST = 8V unless otherwise noted. (Note 2)
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Minimum Boost Voltage
Boost Pin Current
RUN/SS Current
I_SW = 1A
I_SW = 1A
1.8
2.5
V
20
30
mA
2.3
µA
RUN/SS Threshold
0.3
0.6
V
PG Threshold Offset
PG Voltage Output Low
PG Pin Leakage
V_FB Rising
V_FB = 1.25V, I_PG = 250µA
V_PG = 2V
90
125 160
mV
0.22
0.4
V
0.1
1
µA
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LT1940E is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3: Current limit is guaranteed by design and/or correlation to static
test. Slope compensation reduces current limit at high duty cycle.
TYPICAL PERFOR A CE CHARACTERISTICS
Efficiency, V_OUT = 1.8V
90
V_OUT = 1.8V
L = 2.2µH (SUMIDA CR43-2R2)
80
V_IN = 5V
70
60
Efficiency, V_OUT = 3.3V
100
V_OUT = 3.3V
L = 3.3µH (SUMIDA CR43-3R3)
90
V_IN = 5V
80
V_IN = 12V
70
V_IN = 18V
60
Efficiency, V_OUT = 5V
100
V_OUT = 5V
L = 4.7µH (SUMIDA CR43-4R7)
90
V_IN = 8V
80
V_IN = 12V
V_IN = 18V
70
50
0
0.5
1.0
LOAD CURRENT (A)
1.5
1940 G01
50
0
0.5
1.0
LOAD CURRENT (A)
1.5
1940 G02
60
0
0.5
1.0
LOAD CURRENT (A)
1.5
1940 G03
Maximum Load Current,
Maximum Load Current,
V_OUT = 1.8V
V_OUT = 3.3V
Switch V_CESAT
B
1.8
1.8
400
1.6
1.6
L = 4.7µH
300
L = 2.2µH
1.4
L = 1.5µH
1.4
L = 3.3µH
200
L = 1µH
1.2
L = 2.2µH
1.2
100
1.0
0 2 4 6 8 10 12 14 16
INPUT VOLTAGE (V)
1940 G04
1.0
0
5
10
15
20
25
INPUT VOLTAGE (V)
1940 G05
0
0
0.5
1.0
1.5
2.0
SW CURRENT (A)
1940 G06
1940i
3