LTC1149 LTC1149-3.3/LTC1149-5 High Efficiency Synchronous Step-Down Switching Regulators DESCRIPTIO FEATURES n Operation to 48V Input Voltage The LTC 1149 series is a family of synchronous step- n Ultrahigh Efficiency: Up to 95% down switching regulator controllers featuring automatic TM n Current Mode Operation for Excellent Line and Burst Mode operation to maintain high efficiencies at Load Transient Response low output currents. These devices drive external comple- n High Efficiency Maintained over Wide Current Range mentary power MOSFETs at switching frequencies up n Logic-Controlled Micropower Shutdown to 250kHz using a constant off-time current-mode archi- n Short-Circuit Protection tecture. n Very Low Dropout Operation: 100% Duty Cycle Special onboard regulation and level-shift circuitry allow n Synchronous FET Switching for High Efficiency operation at input voltages from dropout to 48V (60V n Adaptive Nonoverlap Gate Drives absolute max). The constant off-time architecture main- n Available in 16-Pin Narrow SO Package tains constant ripple current in the inductor, easing the design of wide input range converters. Current mode APPLICATI S operation provides excellent line and load transient response. The operating current level is user-program- n Notebook and Palmtop Computers mable via an external current sense resistor. n Portable Instruments n Battery-Operated Digital Devices The LTC1149 series incorporates automatic power saving n Industrial Power Distribution Burst Mode operation when load currents drop below the n Avionics Systems level required for continuous operation. Standby power is n Telecom Power Supplies reduced to only about 8mW at V = 12V. In shutdown, IN , LTC and LT are registered trademarks of Linear Technology Corporation. both MOSFETs are turned off. Burst Mode is a trademark of Linear Technology Corporation. TYPICAL APPLICATI V IN LTC1149-5 Efficiency C + IN 1N4148 1N4148 100F 100 V IN FIGURE 1 CIRCUIT 100V CAP P-CHANNEL PGATE V = 12V IN IRFR9024 0.068F V 0.047F CC + 90 PDRIVE D1 3.3F V L* CC R ** SENSE 1N5819 62H 0.05 V = 24V V OUT IN LTC1149-5 5V/2A 80 + SHDN1 SENSE 0V = NORMAL 1000pF >2V = SHUTDOWN SHDN2 SENSE I 70 TH + N-CHANNEL C 3300F OUT C NGATE T IRFR024 220F C T SGND P, RGNDS 1k 470pF 60 0.02 0.2 2 *COILTRONICS CTX62-2-MP **KRL SL-1-C1-0R050J LOAD CURRENT (A) 1149 F01 1149 TA01 Figure 1. High Efficiency Step-Down Regulator 1 EFFICIENCY (%) UO UO ULTC1149 LTC1149-3.3/LTC1149-5 ABSOLUTEXAI U RATI GS PACKAGE/ORDER I FOR ATIO Input Supply Voltage (Pin 2)...................... 15V to 60V TOP VIEW ORDER PART V Output Current (Pin 3) .................................. 50mA CC 1 16 CAP NUMBER PGATE V Input Voltage (Pin 5)........................................ 16V CC 2 15 SHDN2 V IN Continuous Output Current (Pins 4, 13) .............. 50mA 3 14 RGND V CC LTC1149CN Sense Voltages (Pins 8, 9) 4 13 NGATE PDRIVE LTC1149CN-3.3 V 12.7V .......................................... 13V to 0.3V IN 5 12 PGND V CC LTC1149CN-5 V < 12.7V............................. (V + 0.3V) to 0.3V 6 11 SGND IN CC C T LTC1149CS V / FB Shutdown Voltages (Pins 10, 15) ............................. 7V 7 10 I TH SHDN1* LTC1149CS-3.3 + 8 9 SENSE Operating Temperature Range .................... 0C to 70C SENSE LTC1149CS-5 Extended Commercial N PACKAGE S PACKAGE 16-LEAD PDIP 16-LEAD PLASTIC SO Temperature Range ............................... 40C to 85C *FIXED OUTPUT VERSIONS Junction Temperature (Note 1)............................ 125C T = 125C, = 70C/ W (N) JMAX JA Storage Temperature Range ................ 65C to 150C T = 125C, = 110C/ W (S) JMAX JA Lead Temperature (Soldering, 10 sec)................. 300C Consult factory for Industrial and Military grade parts. ELECTRICAL CHARACTERISTICS T = 25C, V = 12V, V = 0V (Note 2), unless otherwise noted. A IN 10 SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Feedback Voltage (LTC1149 Only) V = 9V l 1.21 1.25 1.29 V 10 IN I Feedback Current (LTC1149 Only) l 0.2 1 A 10 V Regulated Output Voltage V = 9V OUT IN LTC1149-3.3 I = 700mA l 3.23 3.33 3.43 V LOAD LTC1149-5 I = 700mA l 4.9 5.05 5.2 V LOAD V Output Voltage Line Regulation V = 9V to 48V, I = 50mA 40 0 40 mV OUT IN LOAD Output Voltage Load Regulation LTC1149-3.3 5mA < I < 2A l 40 65 mV LOAD LTC1149-5 5mA < I < 2A l 60 100 mV LOAD Burst Mode Output Ripple I = 0A 50 mV LOAD P-P I Input DC Supply Current (Note 3) 2 Normal Mode V = 12V 2.0 2.8 mA IN V = 48V 2.2 3.0 mA IN Burst Mode V = 12V 0.6 0.9 mA IN V = 48V 0.8 1.1 mA IN Shutdown V = 12V, V = 2V 135 170 A IN 15 V = 48V, V = 2V 300 390 A IN 15 V Internal Regulator Voltage V = 12V to 48V l 9.75 10.25 11 V CC IN (Sets MOSFET Gate Drive Levels) I = 20mA 3 V V V Dropout Voltage V = 5V, I = 10mA 200 250 mV 2 3 CC IN 3 V V P-Gate to Source Voltage (Off) V = 12V l 0.2 0 V IN 1 IN V = 48V l 0.2 0 V IN 2 U WU U W W W