LTC1143 Datasheet, PDF (1/20 Pages) Linear Technology – Dual High Efficiency SO-16 Step-Down Switching Regulator Controllers

LTC1143/LTC1143L
LTC1143L-ADJ
Dual High Efficiency SO-16
Step-Down Switching Regulator
Controllers
FEATURES
DESCRIPTION
s _{Dual Outputs}
LTC1143, LTC1143L: 3.3V, 5V
LTC1143L-ADJ: Dual Adjustable
s _{Very High Efficiency: Over 95% Possible}
s _{Current Mode Operation for Excellent Line and Load}
Transient Response
s _{High Efficiency Maintained over Three Decades of}
Output Current
s _{Low Standby Current at Light Loads: 160µA/Output}
s _{Logic-Controlled Shutdown (LTC1143, LTC1143L)}
s _{Wide VIN Range: 3.5V to 16V}
(LTC1143L, LTC1143L-ADJ)
s _{Very Low Dropout Operation: 100% Duty Cycle}
s _{Available in Narrow 16-Pin SO Package}
U
APPLICATIONS
The LTC1143 series is a dual step-down switching regulator
controller featuring automatic Burst Mode^TM 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.
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 V_IN = 3.5V. 100% duty cycle provides
low dropout regulation limited only by the R_DS(ON) of the
external MOSFET and resistance of the inductor and
current sense resistor.
s _{Personal Digital Assistants}
s _{Notebook and Palmtop Computers}
s _{Battery-Operated Digital Devices}
s _{Portable Instruments}
s _{DC Power Distribution Systems}
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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
TYPICAL APPLICATION
V_IN
4V TO 14V
V_OUT1
3.3V/2A
R_SENSE1
0.05Ω
C_IN1
22µF
25V
×2
L1
27µH
0.22µF
P1A
13
V_IN1
4
P-DRIVE 1
1 _{SENSE+ 1}
0.22µF
5
V_IN2
P1B
12
P-DRIVE 2
SENSE⁺ 2 ⁹
+ ^CIN2
22µF
25V
×2
L2
27µH
R_SENSE2
0.05Ω
1000pF
LTC1143L-ADJ
1000pF
C_OUT1
220µF
10V
×2
R1
49.9k
1%
R2
82.5k
1%
100pF
SENSE^– 1
D1
16
MBRS320T3
2 ^VFB1
GND1
3
C_T1
14
I_TH1
15
R_C1
1k
I_TH2 C_T2
7
6
R_C2
1k
SENSE^– 2
8
D2
MBRS320T3
V_{FB2 10}
GND2
11
R4
49.9k
+
1%
100pF
R3
49.9k
1%
L1, L2: SUMIDA CDRH125-270
C_T1
300pF
C_C1
C_C2
3300pF 3300pF
C_T2
300pF
P1: SILICONIX Si4953DY/FAIRCHILD NDS8947
R_SENSE1, R_SENSE2: DALE WSL-2010-.05
Figure 1. High Efficiency Dual 3.3V/2.5V Regulator
V_OUT2
2.5V/2A
C_OUT2
220µF
10V
×2
1143 F01
1