LINEAR TECHNOLOGY - 1 LTC1148 Data Sheet

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 Transient Response Burst Mode TM 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 160µA Standby Current at Light Loads 250k Hz using a constant off-time current-mode architec- Logic Controlled Micropower Shutdown: IQ < 20µA ture providing constant ripple current in the inductor. Wide VIN Range: 3.5V* to 20V

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 RDS(ON) of the external MOSFET

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 maximum efficiency at high currents with an automatic low

APPLICATIO S

current operating mode, called Burst Mode operation, which

Notebook and Palmtop Computers reduces switching losses. Standby power is reduced to only Portable Instruments EF FI CI EN CY 2m W at VIN = 10V (at IOUT = 0). Load currents in Burst Mode Battery-Operated Digital Devices operation are typically 0m A to 300m A. 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

VIN (5.2V TO 18V)

VIN = 6V

P-CHANNEL VIN = 10V

P-DRIVE L*

Si4431DY RSENSE**

LTC1148HV-5 62µH 0.05Ω

0V = NORMAL

SHUTDOWN

>1.5V = SHUTDOWN

SENSE+

ITH 1000p F

SENSE–

RC COUT

N-CHANNEL D1

1k N-DRIVE 390µF

CT Si4412DY MBRS140T3

SGND PGND

470p FCC

3300p F LT1148 • TA01

COILTRONICS CTX62-2-MP 0.02 0.2

KRL SL-1-C1-0R050J LOAD CURRENT (A)

LTC1148 • TA01

Figure 1. High Efficiency Step-Down Converter

114835fd