SP1937

SP1937 DC-DC Step-Up Converter for White LED DESCRIPTION The SP1937 is a step-up DC/DC converter for white LED driver with constant current. The device can driver one to four LEDs in series from a single cell Lithium Ion battery. Internal functions include current limiting; thermal shutdown and soft-start to prevent damage operate status. The SP1937 DC/DC converter operates at 1.2MHz and low output capacitor as small as 0.22uF; apply to Lithium-Ion powered systems. A low 95mV (Typ) reference voltage minimizes power loss in the current setting resistor for better efficiency. APPLICATIONS Battery Power Equipment Notebook Computers PDA Cellular Phone Digital Cameras MP3 Players GPS Receivers FEATURES Fast 1.2MHz Switching Frequency High Efficiency up to 85% Drives up to Four LEDs From 3.2V Supply Low Quiescent Current Disconnects LEDs in Shutdown Mode Internal Over Temperature and Current Limiting Shutdown Function 36V Rugged Bipolar Switch Small Package SOT-23-5L & SOT-353 PIN CONFIGURATION SOT-23-5L SOT-353 ( SC-70-5L ) PART MARKING SOT-23-5L SOT-353 ( SC-70-5L ) 2007/07/10 Ver.3 Page 1 SP1937 DC-DC Step-Up Converter for White LED TYPICAL APPLCATION CIRCUIT PIN DESCRIPTION SP1937S25RG Pin Symbol 1 SW 2 GND 3 FB 4 SHDN 5 VIN SP1937S36RG Pin 1 2 3 4 5 6 Description Switch Pin. Ground Pin Feedback Pin. Shutdown Pin. Active-low enable Supply Voltage Input Symbol SW GND FB SHDN GND VIN Description Switch Pin. Ground Pin Feedback Pin. Shutdown Pin. Active-low enable Ground Pin Supply Voltage Input ORDERING INFORMATION Part Number Package SP1937S25RG SOT-23-5L SP1937S35RG SOT-353 ( SC-70-5L ) ※ Week Code : A ~ Z( 1 ~ 26 ) ; a ~ z( 27 ~ 52 ) ※ SP1937S25RG : Tape Reel ; Pb – Free ※ SP1937S35RG : Tape Reel ; Pb – Free Part Marking 97YW 97YW 2007/07/10 Ver.3 Page 2 SP1937 DC-DC Step-Up Converter for White LED BLOCK DIAGRAM ABSOULTE MAXIMUM RATINGS (TA=25℃ Unless otherwise specified) Parameter DC Supply Voltage SW Voltage FB Voltage SHDN Voltage Operating Temperature Maximum Junction Temperature Storage Temperature Symbol VIN VSW VFB VSHDN TOPR TJ(Max) TS Value 20 36 10 10 -40～85 125 -65～150 Unit V V V V ℃ ℃ ℃ The IC has a protection circuit against static electricity. Do not apply high static electricity or high voltage that exceeds the performance of the protection circuit to the IC. 2007/07/10 Ver.3 Page 3 SP1937 DC-DC Step-Up Converter for White LED ELECTRICAL CHARACTERISTICS (TA=25℃, VIN=3V, VSHDN=3V, Unless otherwise specified) Parameter Operating Voltage Feedback Voltage FB Pin Bias Current Supply Current Switching Frequency Maximum Duty Cycle Switch Current Limit Switch Leakage Current Switch Vcesat SHDN Voltage High SHDN Voltage Low SHDN Pin Bias Current Conditions ISW=100mA, Duty Cycle = 66% VSHDN = 0V 0.8 VSW= 5V ISW = 200mA 1.5 0.4 90 Min. 2.5 86 Typ. Max. 20.0 110 150 3.5 1.0 1.6 5 Unit V mV nA mA μA MHz % mA μA mV V V uA 2.8 0.1 1.2 85 320 0.01 150 2007/07/10 Ver.3 Page 4 SP1937 DC-DC Step-Up Converter for White LED APPLICATION INFORMATION CH1: VCC / CH2: Vsw / CH3: Inductor current / R1= 6.8Ω Vin=3V；Vout=8.972V；Iout=14.624mA Vin=3.75V；Vout=8.957V；Iout=14.698mA Vin=5V；Vout=8.963V；Iout=14.869mA 2007/07/10 Vin=5.5V；Vout=8.959V；Iout=14.836mA Page 5 Ver.3 SP1937 DC-DC Step-Up Converter for White LED APPLICATION CIRCUIT ( For Portable System --- Series ) 2007/07/10 Ver.3 Page 6 SP1937 DC-DC Step-Up Converter for White LED APPLICATION CIRCUIT ( For LCD Panel --- Series & Parallel ) 2007/07/10 Ver.3 Page 7 SP1937 DC-DC Step-Up Converter for White LED SOT-23-5L PACKAGE OUTLINE 2007/07/10 Ver.3 Page 8 SP1937 DC-DC Step-Up Converter for White LED SOT-353 PACKAGE OUTLINE 2007/07/10 Ver.3 Page 9 SP1937 DC-DC Step-Up Converter for White LED Information provided is alleged to be exact and consistent. SYNC Power Corporation presumes no responsibility for the penalties of use of such information or for any violation of patents or other rights of third parties which may result from its use. No license is granted by allegation or otherwise under any patent or patent rights of SYNC Power Corporation. Conditions mentioned in this publication are subject to change without notice. This publication surpasses and replaces all information previously supplied. SYNC Power Corporation products are not authorized for use as critical components in life support devices or systems without express written approval of SYNC Power Corporation. ©The SYNC Power logo is a registered trademark of SYNC Power Corporation ©2004 SYNC Power Corporation – Printed in Taiwan – All Rights Reserved SYNC Power Corporation 9F-5, No.3-2, Park Street NanKang District (NKSP), Taipei, Taiwan 115 Phone: 886-2-2655-8178 Fax: 886-2-2655-8468 http://www.syncpower.com 2007/07/10 Ver.3 Page 10