LTC1143/LTC1143L
LTC1143L-ADJ
Dual High Efficiency SO-16
Step-Down Switching Regulator
Controllers
U
FEATURES
DESCRIPTION
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TheLTC1143seriesisadualstep-downswitchingregulator
controller featuring automatic Burst ModeTM operation to
maintain high efficiencies at low output currents. This
device is composed of two separate regulator blocks,
each driving an external power MOSFET at switching
frequenciesupto400kHzusingaconstantoff-timecurrent
mode architecture. Both fixed and adjustable voltages are
available.
Dual Outputs
LTC1143, LTC1143L: 3.3V, 5V
LTC1143L-ADJ: Dual Adjustable
Very High Efficiency: Over 95% Possible
Current Mode Operation for Excellent Line and Load
Transient Response
High Efficiency Maintained over Three Decades of
Output Current
Low Standby Current at Light Loads: 160µA/Output
Logic-Controlled Shutdown (LTC1143, LTC1143L)
Wide VIN Range: 3.5V to 16V
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The operating current level for both regulators is user-
programmable via an external current sense resistor.
Wide input supply range allows operation from 4V to 14V
(16V maximum). The LTC1143L and LTC1143L-ADJ
extend operation to VIN = 3.5V. 100% duty cycle provides
low dropout regulation limited only by the RDS(ON) of the
external MOSFET and resistance of the inductor and
current sense resistor.
(LTC1143L, LTC1143L-ADJ)
Very Low Dropout Operation: 100% Duty Cycle
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Available in NarrUow 16-Pin SO Package
APPLICATIONS
The LTC1143 series is ideal for applications requiring dual
output voltages with high conversion efficiencies over a
wide load current range in a small amount of board space.
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Personal Digital Assistants
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Notebook and Palmtop Computers
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Battery-Operated Digital Devices
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Portable Instruments
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
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DC Power Distribution Systems
U
V
TYPICAL APPLICATION
IN
4V TO 14V
C
IN2
+
C
+
IN1
22µF
25V
× 2
22µF
25V
× 2
0.22µF
P1A
0.22µF
P1B
13
5
V
V
IN1
IN2
4
1
12
9
L2
27µH
L1
27µH
R
R
SENSE2
0.05Ω
SENSE1
P-DRIVE 1
P-DRIVE 2
0.05Ω
V
V
OUT1
OUT2
2.5V/2A
3.3V/2A
+
+
SENSE
SENSE
1
SENSE
SENSE
2
2
1000pF
D1
LTC1143L-ADJ
1000pF
D2
–
–
1
C
R4
OUT1
+
R2
82.5k
1%
8
16
C
OUT2
+
220µF
10V
49.9k
1%
220µF
MBRS320T3
MBRS320T3
10V
× 2
V
FB2
× 2
V
FB1
10
2
R1
R3
49.9k
1%
C
T2
6
GND1
3
C
I
I
GND2
11
T1
14
TH2
7
TH1
15
49.9k
1%
100pF
100pF
R
R
C2
1k
C1
1k
C
C
C
C
C1
3300pF
T1
300pF
C2
3300pF
T2
300pF
L1, L2: SUMIDA CDRH125-270
P1: SILICONIX Si4953DY/FAIRCHILD NDS8947
: DALE WSL-2010-.05
R
R
SENSE1, SENSE2
1143 F01
Figure 1. High Efficiency Dual 3.3V/2.5V Regulator
1