LTC1574 LTC1574-3.3/LTC1574-5 High Efficiency Step-Down DC/DC Converters with Internal Schottky Diode FEATURES DESCRIPTIO n High Efficiency: Up to 94% The LTC 1574 is a family of easy-to-use current mode n Usable in Noise-Sensitive Products DC/DC converters ideally suited for 9V to 5V, 5V to 3.3V n Peak Inductor Current Independent of Inductor Value and inverting operation. With an internal 0.9W switch (at n Short-Circuit Protection a supply voltage of 12V) and a low forward drop Schottky n Internal Low Forward Drop Schottky Diode diode (0.450V typ at 200mA, T = 25 C), the LTC1574 A n Only Three External Components Required requires only three external components to construct a n Wide V Range: 4V to 18.5V (Absolute Maximum) complete high efficiency DC/DC converter. IN n Low Dropout Operation Under no load condition, the LTC1574 draws only 130m A. n Low-Battery Detector In shutdown, it draws a mere 2m A making this converter n Pin Selectable Current Limit ideal for battery-powered applications. In dropout, the n Internal 0.9W Power Switch: V < 11V IN internal P-channel MOSFET switch is turned on continu- n Standby Current: 130m A ously allowing the user to maximize the life of the battery n Active Low Micropower Shutdown source. U The maximum inductor current of the LTC1574 family is APPLICATIO S pin selectable to either 340mA or 600mA, optimizing n Inverting Converters efficiency for a wide range of applications. Operation up to n Step-Down Converters 200kHz permits the use of small surface mount inductors n Memory Backup Supply and capacitors. n Portable Instruments For applications requiring higher output current or ultra- n Battery-Powered Equipment high efficiency, see the LTC1148 or LTC1265 data sheets. n Distributed Power Systems For detailed applications information, see the LTC1174 and LTC are registered trademarks and LT is a trademark of Linear Technology Corporation. data sheet. TYPICAL APPLICATIO LTC1574-5 Efficiency High Efficiency Step-Down Converter 100 L = 100m H V IN V = 5V OUT 95 V = 6V 5.5V to IN I = 0V PGM 16V + 5 22m F* 90 V 35V IN V = 9V 12 IN 7 LB SHDN IN 85 LTC1574-5 11 10 LB V OUT OUT 100m H 80 6 5V 3, 14 I SW PGM 175mA + 100m F* GND 75 10V 2, 4, 13, 15 1574 TA01 70 * AVX TPSD226K035 1 10 100 200 ** AVX TPSD107K010 LOAD CURRENT (mA) COILTRONICS CTX100-4 1574 TA02 1 EFFICIENCY (%) U ULTC1574 LTC1574-3.3/LTC1574-5 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) TOP VIEW ORDER PART (Voltage Referred to GND Pin) NC 1 16 NC NUMBER Input Supply Voltage (Pin 5) ................. 0.3V to 18.5V GND 2 15 GND Switch Current (Pin 3, 14) ........................................ 1A SW 3 14 SW LTC1574CS Switch Voltage (Pin 3, 14) .......................... V 18.5V IN GND 4 13 GND LTC1574CS-3.3 Operating Temperature Range .................... 0 C to 70 C V 5 12 LB IN IN LTC1574CS-5 Junction Temperature (Note 2)............................ 125 C I 6 11 LB PGM OUT Storage Temperature Range ................. 65 C to 150 C SHDN 7 10 V (V *) OUT FB Lead Temperature (Soldering, 10 sec).................. 300 C NC 8 9 NC S PACKAGE 16-LEAD PLASTIC SO *ADJUSTABLE OUTPUT VERSION T = 125C, q = 110C/W JMAX JA Consult factory for Industrial and Military grade parts. ELECTRICAL CHARACTERISTICS The l denotes specifications which apply over the full operating temperature range, otherwise specifications are at T = 25 C. V = 9V, SHDN = V , I = 0V, unless otherwise specified. A IN IN PGM SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS I Feedback Current into Pin 10 LTC1574 1 m A FB V Feedback Voltage LTC1574 l 1.20 1.25 1.30 V FB V Regulated Output Voltage LTC1574-3.3 l 3.14 3.30 3.46 V OUT LTC1574-5 l 4.75 5.00 5.25 V D V Output Voltage Line V = 6V to 12V, I = 100mA, I = V (Note 3) 10 70 mV OUT IN LOAD PGM IN Regulation Output Voltage Load LTC1574-3.3 (Note 3) 20mA < I < 175mA, I = 0V 5 70 mV LOAD PGM Regulation 20mA < I < 400mA, I = V 45 70 mV LOAD PGM IN LTC1574-5 (Note 3) 20mA < I < 175mA, I = 0V 5 70 mV LOAD PGM 20mA < I < 400mA, I = V 50 70 mV LOAD PGM IN I Input DC Supply Current (Note 4) Q Active Mode 4V < V < 16V, I = 0V 450 600 m A IN PGM Sleep Mode 4V < V < 16V 130 180 m A IN Shutdown (Note 5) SHDN = 0V, 4V < V < 16V 2 25 m A IN V Low-Battery Trip Point 1.25 1.4 V LBTRIP I Current into Pin 12 0.5 m A LBIN I Current Sunk by Pin 11 V = 0.4V, V = 0V 0.5 1.0 1.5 mA LBOUT LBOUT LBIN V = 5V, V = 10V 1.0 m A LBOUT LBIN V Comparator Hysteresis 7.5 15 30 mV HYST I Current Limit I = V , V = 0V l 0.54 0.60 0.83 A PEAK PGM IN OUT I = 0V, V = 0V l 0.27 0.34 0.53 A PGM OUT R ON Resistance of Switch l 0.9 1.55 W ON t Switch Off Time V at Regulated Value 3 4 5 m s OFF OUT V SHDN Pin High Minimum Voltage at Pin 7 for Device to Be Active 1.2 V IH V SHDN Pin Low Maximum Voltage at Pin 7 for Device to Be in Shutdown 0.75 V IL 2 U WWW