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LTC1149CS-5 Datasheet Download

Part No.:
LTC1149CS-5
Download:
Download Datasheet
Description:
[High Efficiency Synchronous Step-Down Switching Regulators]
File Size:
393 K
Page:
20 Pages
Logo:
Manufacturer:
LINER [ LINEAR TECHNOLOGY ]
PCB Prototype
 LTC1149CS-5 Datasheet Page:2LTC1149CS-5 Datasheet Page:3LTC1149CS-5 Datasheet Page:4LTC1149CS-5 Datasheet Page:5LTC1149CS-5 Datasheet Page:6LTC1149CS-5 Datasheet Page:7LTC1149CS-5 Datasheet Page:8LTC1149CS-5 Datasheet Page:9 
LTC1149
LTC1149-3.3/LTC1149-5
High Efficiency Synchronous
Step-Down Switching Regulators
FEATURES
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DESCRIPTIO
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Operation to 48V Input Voltage
Ultrahigh Efficiency: Up to 95%
Current Mode Operation for Excellent Line and
Load Transient Response
High Efficiency Maintained over Wide Current Range
Logic-Controlled Micropower Shutdown
Short-Circuit Protection
Very Low Dropout Operation: 100% Duty Cycle
Synchronous FET Switching for High Efficiency
Adaptive Nonoverlap Gate Drives
Available in 16-Pin Narrow SO Package
The LTC
®
1149 series is a family of synchronous step-
down switching regulator controllers featuring automatic
Burst Mode
TM
operation to maintain high efficiencies at
low output currents. These devices drive external comple-
mentary power MOSFETs at switching frequencies up
to 250kHz using a constant off-time current-mode archi-
tecture.
Special onboard regulation and level-shift circuitry allow
operation at input voltages from dropout to 48V (60V
absolute max). The constant off-time architecture main-
tains constant ripple current in the inductor, easing the
design of wide input range converters. Current mode
operation provides excellent line and load transient
response. The operating current level is user-program-
mable via an external current sense resistor.
The LTC1149 series incorporates automatic power saving
Burst Mode operation when load currents drop below the
level required for continuous operation. Standby power is
reduced to only about 8mW at V
IN
= 12V. In shutdown,
both MOSFETs are turned off.
APPLICATI
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Notebook and Palmtop Computers
Portable Instruments
Battery-Operated Digital Devices
Industrial Power Distribution
Avionics Systems
Telecom Power Supplies
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
TYPICAL APPLICATI
1N4148
CAP
0.068µF
V
IN
V
IN
1N4148
PGATE
PDRIVE
0.047µF
D1
1N5819
P-CHANNEL
IRFR9024
L*
62µH
+
C
IN
100µF
100V
+
3.3µF
V
CC
V
CC
EFFICIENCY (%)
R
SENSE
**
0.05Ω
LTC1149-5
0V = NORMAL
>2V = SHUTDOWN
3300µF
1k
C
T
470pF
SHDN1
SHDN2
I
TH
C
T
SGND
SENSE
+
SENSE
NGATE
P, RGNDS
*COILTRONICS CTX62-2-MP
**KRL SL-1-C1-0R050J
1000pF
N-CHANNEL
IRFR024
V
OUT
5V/2A
+
C
OUT
220µF
60
0.02
1149 F01
Figure 1. High Efficiency Step-Down Regulator
U
LTC1149-5 Efficiency
100
FIGURE 1 CIRCUIT
V
IN
= 12V
90
V
IN
= 24V
80
70
0.2
LOAD CURRENT (A)
2
1149 TA01
UO
UO
1