LTC3521
4
3521fb
For more information www.linear.com/LTC3521
Typical perForMance characTerisTics
Buck-Boost Efficiency vs Load
Current, Li-Ion to 3.3V
Buck Efficiency vs Load Current,
Li-Ion to 2.5V
Buck Efficiency vs Load Current,
Li-Ion to 1.8V
Buck Burst Mode Current
Threshold vs V
IN
0.1 1
10
100 1000
LOAD CURRENT (mA)
EFFICIENCY (%)
3521 G01
0
20
40
60
80
100
120
140
0
20
30
40
50
60
70
80
90
100
10
Burst Mode
OPERATION
Burst Mode
POWER LOSS
V
IN
= 2.7V
V
IN
= 4.2V
PWM MODE
0.1 1
10
100 1000
LOAD CURRENT (mA)
0
EFFICIENCY (%)
POWER LOSS (mW)
20
30
40
50
60
70
3521 G02
80
90
0
20
40
60
80
100
120
140
10
Burst Mode
OPERATION
Burst Mode
POWER LOSS
V
IN
= 3.6V
V
IN
= 4.2V
PWM MODE
0.1 1
10
100 1000
LOAD CURRENT (mA)
0
EFFICIENCY (%)
POWER LOSS (mW)
20
30
40
50
60
70
3521 G03
80
90
100
0
20
40
60
80
100
120
140
10
Burst Mode
OPERATION
Burst Mode
POWER LOSS
PWM MODE
V
IN
= 2.7V
V
IN
= 4.2V
T
A
= 25°C, unless otherwise noted.
V
IN
(V)
1.5
40
50
5
30
20
2.5 3.5
2
3 4 4.5 5.5
10
0
60
3521 G04
V
OUT
= 2.5V
V
OUT
= 1.8V
V
OUT
= 1.2V
elecTrical characTerisTics
Note 3: Current measurements are performed when the LTC3521 is not
switching. The current limit values in operation will be somewhat higher
due to the propagation delay of the comparators.
Note 4: The LTC3521 is tested in a proprietary test mode that connects
each FB pin to the output of the respective error amplifier.
Note 5: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
Note 6: Shutdown current is measured on the V
IN
pin and does not include
PMOS switch leakage.
