LTC1148
LTC1148-3.3/LTC1148-5
High Efficiency Synchronous
Step-Down Switching Regulators
FEATURES
DESCRIPTIO
Ultrahigh Efficiency: Over 95% Possible The LTC 1148 series is a family of synchronous step-
Current-Mode Operation for Excellent Line and Load down switching regulator controllers featuring automatic
TM
Transient Response Burst Mode operation to maintain high efficiencies at
High Efficiency Maintained Over Three Decades of low output currents. These devices drive external comple-
Output Current mentary power MOSFETs at switching frequencies up to
Low 160A Standby Current at Light Loads 250kHz using a constant off-time current-mode architec-
Logic Controlled Micropower Shutdown: I < 20A ture providing constant ripple current in the inductor.
Q
Wide V Range: 3.5V* to 20V
IN
The operating current level is user-programmable via an
Short-Circuit Protection
external current sense resistor. Wide input supply range
Very Low Dropout Operation: 100% Duty Cycle
allows operation from 3.5V* to 18V (20V maximum).
Synchronous FET Switching for High Efficiency
Constant off-time architecture provides low dropout regu-
Adaptive Nonoverlap Gate Drives
lation limited by only the R of the external MOSFET
DS(ON)
Output Can Be Externally Held High in Shutdown
and resistance of the inductor and current sense resistor.
Available in 14-Pin Narrow SO Package
The LTC1148 series combines synchronous switching for
U
maximum efficiency at high currents with an automatic low
APPLICATIO S
operation, which
current operating mode, called Burst Mode
Notebook and Palmtop Computers
reduces switching losses. Standby power is reduced to only
Portable Instruments
2mW at V = 10V (at I = 0). Load currents in Burst Mode
IN OUT
Battery-Operated Digital Devices operation are typically 0mA to 300mA.
Cellular Telephones
For operation up to 48V input, see the LTC1149 and
DC Power Distribution Systems
LTC1159 data sheets and Application Note 54.
GPS Systems
, 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.
TYPICAL APPLICATIO
LTC1148-5 Efficiency
V (5.2V TO 18V)
100
IN
V = 6V
IN
+ +
C
IN
1F
100F
V
IN
95
P-CHANNEL V = 10V
IN
P-DRIVE
L*
R **
Si4431DY SENSE
62H
LTC1148HV-5 0.05
V
OUT
0V = NORMAL
SHUTDOWN
5V/2A
>1.5V = SHUTDOWN
+ 90
SENSE
1000pF
I
TH
SENSE
C +
T
C
R OUT
C
N-CHANNEL D1
N-DRIVE 85
390F
1k
Si4412DY MBRS140T3
C
T
SGND PGND
C 470pF
C
3300pF
LT1148 TA01
80
0.02 0.2 2
*COILTRONICS CTX62-2-MP
**KRL SL-1-C1-0R050J LOAD CURRENT (A)
LTC1148 TA01
Figure 1. High Efficiency Step-Down Converter
114835fd
1
EFFICIENCY (%)
U
ULTC1148
LTC1148-3.3/LTC1148-5
ABSOLUTEXAI U RATI GS PACKAGE/ORDER I FOR ATIO
(Note 1)
Input Supply Voltage (Pin 3)
ORDER PART
NUMBER
LTC1148 and LTC1148L Series ............ 16V to 0.3V
TOP VIEW
LTC1148HV Series ............................... 20V to 0.3V
LTC1148CN
Continuous Output Current (Pins 1, 14) .............. 50mA 1 N-DRIVE
P-DRIVE 14
LTC1148HVCN
2 NC
Sense Voltages (Pins 7, 8) NC 13
LTC1148CN-3.3
3 PGND
V 12
LTC1148HV (Adjustable Only) IN
LTC1148HVCN-3.3
4 SGND
C 11
T
V 12.7V ...................................... 13V to 0.3V
IN
LTC1148CN-5
5 SHUTDOWN
INTV 10
CC
V < 12.7V ......................... (V + 0.3V) to 0.3V
IN IN
LTC1148HVCN-5
6 V *
I 9
TH FB
Operating Ambient Temperature Range ...... 0C to 70C
+
LTC1148CS
7 SENSE
SENSE 8
Extended Commercial and Industrial
LTC1148HVCS
N PACKAGE
S PACKAGE
Temperature Range ............................... 40C to 85C
14-LEAD PDIP LTC1148LCS
14-LEAD PLASTIC SO
Junction Temperature (Note 2)............................ 125C
*FIXED OUTPUT VERSIONS = NC LTC1148CS-3.3
Storage Temperature Range ................ 65C to 150C
LTC1148HVCS-3.3
T = 125C, = 70C/ W (N)
JMAX JA
Lead Temperature (Soldering, 10 sec)................. 300C T = 125C, = 110C/ W (S)
JMAX JA
LTC1148LCS-3.3
LTC1148CS-5
LTC1148HVCS-5
LTC1148HVIS-5
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The denotes the specifications which apply over the full operating
ELECTRICAL CHARACTERISTICS
temperature range, otherwise specifications are at T = 25C. V = 10V, V = 0V unless otherwise noted.
A IN SHUTDOWN
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V Feedback Voltage (LTC1148, LTC1148L, V = 9V 1.21 1.25 1.29 V
9 IN
LTC1148HV)
I Feedback Current (LTC1148, LTC1148L, 0.2 1 A
9
LTC1148HV)
V Regulated Output Voltage V = 9V
OUT IN
LTC1148-3.3, LTC1148HV-3.3, LTC1148L-3.3 I = 700mA 3.23 3.33 3.43 V
LOAD
LTC1148-5, LTC1148HV-5 I = 700mA 4.90 5.05 5.20 V
LOAD
V Output Voltage Line Regulation V = 7V to 12V, I = 50mA 40 0 40 mV
OUT IN LOAD
Output Voltage Load Regulation
LTC1148-3.3, LTC1148HV-3.3, LTC1148L-3.3 5mA < I < 2A 40 65 mV
LOAD
LTC1148-5, LTC1148HV-5 5mA < I < 2A 60 100 mV
LOAD
Output Ripple (Burst Mode) I = 0A 50 mV
LOAD P-P
I Input DC Supply Current (Note 3) (Note 7)
Q
LTC1148 Series
Normal Mode 4V < V < 12V 1.6 2.1 mA
IN
Sleep Mode 4V < V < 12V 160 230 A
IN
Sleep Mode (LTC1148-5) 6V < V < 12V 160 230 A
IN
Shutdown V = 2.1V, 4V < V < 12V 10 20 A
SHUTDOWN IN
LTC1148HV Series
Normal Mode 4V < V < 18V 1.6 2.3 mA
IN
Sleep Mode 4V < V < 18V 160 250 A
IN
Sleep Mode (LTC1148HV-5) 6V < V < 18V 160 250 A
IN
Shutdown V = 2.1V, 4V < V < 18V 10 22 A
SHUTDOWN IN
LTC1148L Series
Normal Mode 3.5V < V < 12V 1.6 2.1 mA
IN
Sleep Mode 3.5V < V < 12V 160 230 A
IN
Shutdown V = 2.1V, 3.5V < V < 12V 10 20 A
SHUTDOWN IN
114835fd
2
U U W W W
WU