Datasheet
LTC3538
3
3538fb
LOAD CURRENT (mA)
0.1 1 10 100 1000
0.1
1
10
100
1000
EFFICIENCY (%)
POWER LOSS (mW)
100
80
60
40
20
0
90
70
50
30
10
3538 G02
Burst Mode
OPERATION
POWER LOSS
FIXED FREQUENCY
POWER LOSS BURST
FIXED FREQUENCY
LOAD CURRENT (mA)
0.1 1 10 100 1000
EFFICIENCY (%)
100
80
60
40
20
10
90
70
50
30
3538 G01
V
IN
= 2.7V
V
IN
= 3.6V
V
IN
= 4.2V
Burst Mode
OPERATION
PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Duty Cycle FB = 1.2V
●
0%
Frequency Accuracy
●
0.8 1 1.2 MHz
Internal Soft-Start Time 1.5 ms
Error Amp A
VOL
80 dB
Error Amp Source Current V
C
= 1.5V, FB = OV –13 μA
Error Amp Sink Current V
C
= 1.5V, FB = 1.2V 130 μA
V
C
Shutdown Threshold (Off) IC is Disabled
●
0.25 V
V
C
Output Current in Shutdown V
C
= GND –1 –3 μA
BURST Threshold (High)
●
1.4 V
BURST Threshold (Low)
●
0.4 V
BURST Input Current V
BURST
= 3.6V 0.1 1 μA
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 LTC3538 is guaranteed to meet performance specifi cations
from 0°C to 85°C. Specifi cations over –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3: This IC includes over-temperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when over-temperature protection is active.
Continuous operation above the specifi ed maximum operating junction
temperature may result in device degradation or failure.
Note 4: The IC is tested in a feedback loop to make the measurement.
TYPICAL PERFORMANCE CHARACTERISTICS
Li-Ion to 3.3V Effi ciency
Effi ciency and Power Loss vs
Load Current
Switch Pins Before Entering
Boost Mode
ELECTRICAL CHARACTERISTICS
The ● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. V
IN
= V
OUT
= 3.6V, unless otherwise noted.
T
A
= 25°C unless otherwise noted
50ns/DIV
SW1
2V/DIV
SW2
2V/DIV
3538 G03
V
IN
= 2.9V
V
OUT
= 3.3V AT 500mA