LT1945 Dual Micropower DC/DC Converter with Positive and Negative Outputs FEATURES DESCRIPTION n Generates Well-Regulated Positive and The LT 1945 is a dual micropower DC/DC converter in a Negative Outputs 10-pin MSOP package. Each converter is designed with n Low Quiescent Current: a 350mA current limit and an input voltage range of 1.2V 20A in Active Mode (per Converter) to 15V, making the LT1945 ideal for a wide variety of ap- <1A in Shutdown Mode plications. Both converters feature a quiescent current of n Operates with V as Low as 1.2V only 20A at no load, which further reduces to 0.5A in IN n Low V Switch: 250mV at 300mA shutdown. A current limited, xed off-time control scheme CESAT n Uses Small Surface Mount Components conserves operating current, resulting in high ef ciency n High Output Voltage: Up to 34V over a broad range of load current. The 36V switch allows n Tiny 10-Pin MSOP Package high voltage outputs up to 34V to be easily generated without the use of costly transformers. The LT1945s APPLICATIONS low off-time of 400ns permits the use of tiny, low pro le inductors and capacitors to minimize footprint and cost n Small TFT LCD Panels in space-conscious portable applications. n Handheld Computers n L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Battery Backup All other trademarks are the property of their respective owners. n Digital Cameras TYPICAL APPLICATION Dual Output (+12V, 20V) Converter Ef ciency at V = 3.6V IN C4 90 L1 0.1F D1 10H V IN 85 20V 2.7V +12V OUTPUT 10mA TO 5V 810 80 100pF 365k 20V OUTPUT V SW1 IN 75 2 1 SHDN1 NFB1 70 C1 C2 LT1945 D2 4.7F 1F 65 4 5 SHDN2 FB2 24.9k 60 GND PGND PGND SW2 3 7 9 6 55 50 115k 0.1 1 10 100 C3 LOAD CURRENT (mA) 1F 4.7pF 1945 TA01a 1M L2 D3 10H 12V 20mA C1: TAIYO YUDEN JMK212BJ475 1945 TA01 C2, C3: TAIYO YUDEN TMK316BJ105 C4: TAIYO YUDEN EMK107BJ104 D1, D2, D3: ZETEX ZHCS400 L1, L2: MURATA LQH3C100 1945fa 1 EFFICIENCY (%)LT1945 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW V , SHDN1, SHDN2 Voltage .....................................15V IN NFB1 1 10 SW1 SHDN1 2 9 PGND SW1, SW2 Voltage ....................................................36V GND 3 8 V IN NFB1 Voltage ............................................................3V SHDN2 4 7 PGND FB2 5 6 SW2 FB2 Voltage ............................................................... VIN MS PACKAGE Current into NFB1 Pin ............................................1mA 10-LEAD PLASTIC MSOP T = 125C, = 160C/W JMAX JA Current into FB2 Pin ................................................1mA Junction Temperature ........................................... 125C Operating Temperature Range (Note 2).... 40C to 85C Storage Temperature Range ................... 65C to 150C Lead Temperature (Soldering, 10 sec) .................. 300C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT1945EMS PBF LT1945EMS TRPBF LTTS 10-Lead Plastic MSOP 40C to 85C LT1945IMS PBF LT1945IMS TRPBF LTTS 10-Lead Plastic MSOP 40C to 125C LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT1945EMS LT1945EMS TR LTTS 10-Lead Plastic MSOP 40C to 85C LT1945IMS LT1945IMS TR LTTS 10-Lead Plastic MSOP 40C to 125C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. *The temperature grade is identi ed by a label on the shipping container. For more information on lead free part marking, go to: