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