LTC1143/LTC1143L
LTC1143L-ADJ
Dual High Efficiency SO-16
Step-Down Switching Regulator
Controllers
DESCRIPTION
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FEATURES
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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
(LTC1143L, LTC1143L-ADJ)
Very Low Dropout Operation: 100% Duty Cycle
Available in Narrow 16-Pin SO Package
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APPLICATIONS
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, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
TYPICAL APPLICATION
+
VOUT1
3.3V/2A
RSENSE1
0.05Ω
CIN1
22µF
25V
×2
VIN
4V TO 14V
+
0.22µF
0.22µF
P1A
4
L1
27µH
1
13
VIN1
5
VIN2
P-DRIVE 1
P-DRIVE 2
SENSE + 1
SENSE + 2
1000pF
COUT1
220µF
10V
×2
+
R1
49.9k
1%
R2
82.5k
1%
The operating current level for both regulators is userprogrammable 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.
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.
Personal Digital Assistants
Notebook and Palmtop Computers
Battery-Operated Digital Devices
Portable Instruments
DC Power Distribution Systems
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The LTC1143 series is a dual step-down switching regulator
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
frequencies up to 400kHz using a constant off-time current
mode architecture. Both fixed and adjustable voltages are
available.
2
100pF
L1, L2: SUMIDA CDRH125-270
P1: SILICONIX Si4953DY/FAIRCHILD NDS8947
RSENSE1, RSENSE2: DALE WSL-2010-.05
P1B
12
L2
27µH
SENSE – 2
R4
49.9k
1%
8
D2
MBRS320T3
VFB2
VFB1
3
CT1
300pF
CT1
14
ITH1
15
RC1
1k
CC1
CC2
3300pF 3300pF
VOUT2
2.5V/2A
1000pF
SENSE – 1
GND1
RSENSE2
0.05Ω
9
LTC1143L-ADJ
16
D1
MBRS320T3
CIN2
22µF
25V
×2
ITH2
CT2
7
6
11
10
GND2
100pF
+
R3
49.9k
1%
COUT2
220µF
10V
×2
RC2
1k
CT2
300pF
1143 F01
Figure 1. High Efficiency Dual 3.3V/2.5V Regulator
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