Datasheet

1
LTC1148
LTC1148-3.3/LTC1148-5
114835fd
High Efficiency Synchronous
Step-Down Switching Regulators
LOAD CURRENT (A)
0.02
80
EFFICIENCY (%)
85
90
100
0.2 2
LTC1148 • TA01
95
V
IN
= 6V
V
IN
= 10V
LTC1148-5 Efficiency
Ultrahigh Efficiency: Over 95% Possible
Current-Mode Operation for Excellent Line and Load
Transient Response
High Efficiency Maintained Over Three Decades of
Output Current
Low 160µA Standby Current at Light Loads
Logic Controlled Micropower Shutdown: I
Q
< 20µA
Wide V
IN
Range: 3.5V* to 20V
Short-Circuit Protection
Very Low Dropout Operation: 100% Duty Cycle
Synchronous FET Switching for High Efficiency
Adaptive Nonoverlap Gate Drives
Output Can Be Externally Held High in Shutdown
Available in 14-Pin Narrow SO Package
The LTC
®
1148 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 architec-
ture providing constant ripple current in the inductor.
The operating current level is user-programmable via an
external current sense resistor. Wide input supply range
allows operation from 3.5V* to 18V (20V maximum).
Constant off-time architecture provides low dropout regu-
lation limited by only the R
DS(ON)
of the external MOSFET
and resistance of the inductor and current sense resistor.
The LTC1148 series combines synchronous switching for
maximum efficiency at high currents with an automatic low
current operating mode, called Burst Mode
operation, which
reduces switching losses. Standby power is reduced to only
2mW at V
IN
= 10V (at I
OUT
= 0). Load currents in Burst Mode
operation are typically 0mA to 300mA.
For operation up to 48V input, see the LTC1149 and
LTC1159 data sheets and Application Note 54.
Figure 1. High Efficiency Step-Down Converter
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode
is a trademark of Linear Technology Corporation.
* LTC1148L and LTC1148L-3.3 only.
Protected by U.S. Patents, including 6580258, 5481178.
Notebook and Palmtop Computers
Portable Instruments
Battery-Operated Digital Devices
Cellular Telephones
DC Power Distribution Systems
GPS Systems
0V = NORMAL
>1.5V = SHUTDOWN
P-CHANNEL
Si4431DY
+
1µF
L*
62µH
R
SENSE
**
0.05
V
OUT
5V/2A
+
C
IN
100µF
V
IN
(5.2V TO 18V)
I
TH
C
T
SGND
C
T
470pF
C
C
3300pF
R
C
1k
+
C
OUT
390µF
D1
MBRS140T3
LT1148 • TA01
N-DRIVE
PGND
N-CHANNEL
Si4412DY
V
IN
P-DRIVE
LTC1148HV-5
SHUTDOWN
SENSE
+
SENSE
1000pF
COILTRONICS CTX62-2-MP
KRL SL-1-C1-0R050J
*
**
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U

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