Datasheet

LT1946
3
1946fb
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Feedback Pin Voltage
TEMPERATURE (°C)
–50
FEEDBACK VOLTAGE (V)
1.27
25
1946 G01
1.24
1.22
–25 0 50
1.21
1.20
1.28
1.26
1.25
1.23
75 100 125
FEEDBACK VOLTAGE (V)
0
1400
1200
1000
800
600
400
200
0
0.6 1.0
1946 G02
0.2 0.4
0.8 1.2
OSCILLATOR FREQUENCY (kHz)
T
A
= –30°CT
A
= 100°C
T
A
= 25°C
TEMPERATURE (°C)
–50
0
CURRENT LIMIT (A)
0.6
0.4
0.2
0.8
1.0
1.4
1.2
2.6
2.4
2.2
2.0
–25
25
50 125
1946 G03
1.6
1.8
0
75
100
Oscillator Frequency Current Limit
Switch Saturation Voltage Quiescent Current
Switching Waveforms
for Figure 1 Circuit
SWITCH CURRENT (A)
0
V
CESAT
(V)
0.20
0.25
0.30
1.2
1946 G04
0.15
0.10
0.4 0.80.2 1.40.6 1.0 1.6
0.05
0
0.35
TEMPERATURE (°C)
–50
2.0
QUIESCENT CURRENT (mA)
2.2
2.6
2.8
3.0
75 100
3.8
1946 G05
2.4
–25 0 25 50 125
3.2
3.4
3.6
V
OUT
20mV/DIV
AC COUPLED
V
SW
5V/DIV
0V
I
LI
0.5A/DIV
AC COUPLED
0.5µs/DIV
1946 G06
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3V, V
SHDN
= V
IN
unless otherwise specified. (Note 2)
SYMBOL CONDITIONS MIN TYP MAX UNITS
SHDN Input Voltage High 2.4 V
SHDN Input Voltage Low 0.5 V
SHDN Pin Bias Current V
SHDN
= 3V 16 32 µA
V
SHDN
= 0V 0 0.1 µA
ELECTRICAL CHARACTERISTICS
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LT1946E 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 flows out of FB pin.
Note 4: Current limit guaranteed by design and/or correlation to static test.
Current limit is independent of duty cycle and is guaranteed by design.