Datasheet

LTC3544
4
3544fa
2μs/DIV
V
OUT300
50mV/DIV
AC
COUPLED
I
L
100mA/DIV
SW300
5V/DIV
3544 G04
V
IN
= 3.6V
V
OUT
= 1.8V
T
A
= 25°C
I
LOAD
= 20mA
Burst Mode Operation
300mA Channel
Burst Mode Operation
200mA, A-B Channels
Burst Mode Operation
100mA Channel
V
REF
vs Temperature at 2.25V,
3.6V, 5.5V
Switching Frequency vs Supply
Voltage and Temperature
Effi ciency vs Load Current 300mA
Channel. All Other Channels at
50% Peak Current
TEMPERATURE (°C)
–50
0.785
V
REF
(V)
0.790
0.795
0.800
0805
0.810
0.815
0 50 100
3544 G01
V
IN
= 2.25V
V
IN
= 3.6V
V
IN
= 5.5V
CHANNEL 200A
I
LOAD
= 100mA
ALL CHANNELS OPERATING
SUPPLY VOLTAGE (V)
2
1.5
SWITCHING FREQUENCY (MHz)
2.0
2.5
3.0
34
3544 G02
56
f
OSC
–40°C
f
OSC
0°C
f
OSC
25°C
f
OSC
80°C
I
LOAD
CHANNEL 100 = 50mA
ALL CHANNELS OPERATING
LOAD CURRENT 300mA CHANNEL (A)
30
EFFICIENCY (%)
90
100
20
10
80
50
70
60
40
0.0001 0.01 0.1 1
3544B G03
0
0.001
V
IN
= 3.6V
T
A
= 25°C
V
OUT100
= 1.2V
V
OUT200A
= 0.8V
V
OUT200B
= 1.5V
V
OUT300
= 1.8V
ALL OTHER CHANNELS LOADED 50%
2μs/DIV
V
OUT200B
50mV/DIV
AC
COUPLED
I
L
50mA/DIV
SW2B
5V/DIV
3544 G05
V
IN
= 3.6V
V
OUT
= 1.5V
T
A
= 25°C
I
LOAD
= 15mA
2μs/DIV
V
OUT100
50mV/DIV
AC
COUPLED
I
L
50mA/DIV
SW100
5V/DIV
3544 G06
V
IN
= 3.6V
V
OUT
= 1.2V
T
A
= 25°C
I
LOAD
= 12mA
TYPICAL PERFORMANCE CHARACTERISTICS
Note 3: T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formula:
T
J
= T
A
+ (P
D
)(68°C/W).
Note 4: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature is active. Continuous
operation above the specifi ed maximum operating junction temperature
may impair device reliability.
Note 5: The LTC3544 is tested in a proprietary test mode that connects V
FB
to the output of the error amplifi er.
Note 6: Load regulation is inferred by measuring the regulation loop gain.
Note 7: The QFN switch on-resistance is guaranteed by correlation to wafer
level measurements.
Note 8: Guaranteed by long-term current density limitations.
ELECTRICAL CHARACTERISTICS