+ LTC1433/LTC1434 450mA, Low Noise Current Mode Step-Down DC/DC Converters DESCRIPTION FEATURES n High Efficiency: Up to 93% The LTC 1433/LTC1434 are monolithic pulse width modu- TM n Constant Frequency Adaptive Power Operation lated step-down DC/DC converters. By utilizing current n Input Voltage Range: 3V to 13.5V mode switching techniques, they provide excellent AC and n Internal 0.6 Power Switch (V = 10V) DC load and line regulation. Both devices operate at a fixed IN n Low Dropout Operation: 100% Duty Cycle frequency with the LTC1434 phase-lockable to an external n Low-Battery Detector clock signal. n Internal Power-On Reset Timer Both devices incorporate two internal P-channel power n Current Mode Operation for Excellent Line and Load MOSFETs with a parallel combined resistance of 0.6 (at Transient Response a supply of 10V). The Adaptive Power output stage selec- n Low Quiescent Current: 470A tively drives one or both of the switches at frequencies up n Shutdown Mode Draws Only 15A Supply Current to 700kHz to reduce switching losses and maintain high n 1% Reference Accuracy efficiencies at low output currents. n Available in 16- and 20-Lead Narrow SSOP The LTC1433/LTC1434 are capable of supplying up to U 450mA of output current and boasts a 2.4% output APPLICATIONS voltage accuracy. An internal low-battery detector has the same level of accuracy as the output voltage. A power-on n Cellular Telephones reset timer (POR) is included which generates a signal n Portable Instruments delayed by 65536/f (300ms typ) after the output is n CLK Wireless Modems within 5% of the regulated output voltage. n RF Communications n Distributed Power Systems Ideal for current sensitive applications, the devices draw n Scanners only 470A of quiescent current. In shutdown the devices n Battery-Powered Equipment draw a mere 15A. To further maximize the life of the battery source, the internal P-channel MOSFET switch is , LTC and LT are registered trademarks of Linear Technology Corporation. Adaptive Power is a trademark of Linear Technology Corporation. turned on continuously in dropout. TYPICAL APPLICATION 68F** LTC1433 Efficiency for 0.1F 20V V = 3.3V OUT 100 D1 1 16 V IN V = 5V SSW PWRV 90 IN IN 3.5V TO 12V L1 2 15 PGND NC 100H 10k 3 14 V 80 V = 12V OUT IN BSW SV IN 3.3V LTC1433 + 4 13 100F* NC C OSC 70 10V 5 12 POWER-ON SGND POR V = 9V RESET IN 6 11 RUN/SS I 60 TH 7 10 680pF 0.1F LBO V 5.1k OSENSE 47pF 8 9 50 LBI V PROG 6800pF 40 0.001 0.01 0.1 1 D1: MOTOROLA MBRS130LT3 * AVX TPSD107M010R0100 1433/34 F01 L1: COILCRAFT D03316-104 ** AVX TPSE686M020R0150 LOAD CURRENT (A) 1433/34 TA01 Figure 1. High Efficiency Step-Down Converter 1 EFFICIENCY (%) U ULTC1433/LTC1434 ABSOLUTEXAI U RATI GS (Note 1) (Voltages Referred to PGND Pin) Input Supply Voltage (PWRV , SV ) ... 13.5V to 0.3V RUN/SS, V Voltages PROG IN IN DC Small Switch Current (SSW) ......................... 100mA V 11.7V ...........................................12V to 0.3V IN Peak Small Switch Current (SSW) ..................... 300mA V < 11.7V............................... (V + 0.3V) to 0.3V IN IN Small Switch Voltage Commercial Temperature Range (SSW) ................................(V + 0.3V) to (V 13.5V) LTC1433C/LTC1434C .............................. 0C to 70C IN IN DC Large Switch Current (BSW) ....................... 600mA Extended Commercial Operating Temperature Peak Large Switch Current (BSW) .......................... 1.2A Range (Note 2) ....................................... 40C to 85C Large Switch Voltage Industrial Temperature Range (Note 3) (BSW) ................................(V + 0.3V) to (V 13.5V) LTC1433I/LTC1434I ........................... 40C to 85C IN IN PLLIN, PLL LPF, I , C ........................2.7V to 0.3V Junction Temperature (Note 4)............................. 125C TH OSC POR, LBO ..................................................12V to 0.3V Storage Temperature Range ................. 65C to 150C LBI, V ..............................................10V to 0.3V Lead Temperature (Soldering, 10 sec).................. 300C OSENSE PACKAGE/ORDER I FOR ATIO TOP VIEW ORDER PART ORDER PART TOP VIEW 1 PWRV NUMBER NC 20 NUMBER IN 1 16 PWRV SSW 2 PGND IN SSW 19 2 15 PGND NC LTC1433CGN 3 SV LTC1434CGN NC 18 IN 3 SV BSW 14 LTC1433IGN 4 PLLIN LTC1434IGN IN BSW 17 4 C NC 13 5 PLL LPF OSC SGND 16 5 POR SGND 12 6 C NC 15 OSC 6 I RUN/SS 11 7 POR TH RUN/SS 14 7 V LBO 10 8 I OSENSE NC 13 TH 8 V LBI 9 9 V PROG LBO 12 OSENSE 10 V LBI 11 PROG GN PACKAGE 16-LEAD PLASTIC SSOP GN PACKAGE = 125C, = 150C/ W T JMAX JA 20-LEAD PLASTIC SSOP T = 125C, = 150C/ W JMAX JA Consult factory for Military grade parts. ELECTRICAL CHARACTERISTICS T = 25C, V = 10V, V = 5V, unless otherwise noted. (Notes 2, 3) A IN RUN/SS SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Main Control Loop I V Feedback Current V Pin Open (Note 5) 10 50 nA IN OSENSE PROG V Regulated Output Voltage (Note 5) OSENSE 1.19V (Adjustable) Selected V Pin Open l 1.178 1.190 1.202 V PROG 3.3V Selected V = 0V l 3.220 3.300 3.380 V PROG 5V Selected V = V l 4.880 5.000 5.120 V PROG IN V Output Overvoltage Lockout V Pin Open 1.24 1.28 1.32 V OVL PROG V Reference Voltage Line Regulation V = 3.6V to 13V (Note 5), V Pin Open 0.002 0.01 %/V OSENSE IN PROG V Output Voltage Load Regulation I Sinking 5A (Note 5) l 0.5 0.8 % LOADREG TH I Sourcing 5A (Note 5) l 0.5 0.8 % TH 2 U WU U W W W