AMS1027 DESCRIPTION FEATURES The AMS1027 is a 5-pin thin SOT23 current mode step up converter intended for small, low power applications. The AMS1027 switches at 1.3MHz and allows the use of tiny, low cost capacitors and inductors 2mm or less in height. Internal soft start results in small inrush current and extends battery life.The AMS1027 operates from an input voltage as low as 2.5V and can generate 12V at up to 200mA from a 5V supply. The AMS1027 includes under-voltage lockout, current limiting, and thermal overload protection to prevent damage in the event of an output overload. The AMS1027 is available in a small 5-pin SOT23 package. On Board Power MOSFET Uses Tiny Capacitors and Inductors 1.3MHz Fixed Switching Frequency Internally Compensated Internal Soft-Start Operates with Input Voltage as Low as 2.5V and Output Voltage as High as 22V 12V at 200mA from 5V Input UVLO, Thermal Shutdown Internal Current Limit Available in a SOT23-5 Package APPLICATIONS Camera Phone Flash Handheld Computers and PDAs Digital Still and Video Cameras External Modems Small LCD Displays White LED Driver TYPICAL APPLICATION D1 VIN 5V 5 OFF ON IN 4 EN 2 1 SW AMS1027 GND VOUT 12V 200mA FB 3 Vout=1.25(1+R1/R2) (V) 1 Advanced Monolithic Systems http://www.ams-semitech.com AMS1027 PACKAGE REFERENCE TOP VIEW SW 1 GND 2 FB 3 5 IN 4 EN ABSOLUTE MAXIMUM RATINGS SW Pin ...........................................–0.5V to 25V All Other Pins ................................–0.3V to 6.5V Lead Temperature ....................................260°C Storage Temperature.............. –65°C to +150°C Recommended Operating Conditions Supply Voltage VIN .............................2.5V to 6V Output Voltage VOUT ............................Vin to 22V Operating Temperature............. –40°C to +85°C Functional Block Diagram SW 1 FB 3 - + CONTROL LOGIC + 1.25V ERROR AMPLIFIER PWM COMPARATOR + + - CURRENT SENSE AMPLIFIER 1.3MHz OSC 2 Advanced Monolithic Systems http://www.ams-semitech.com 2 GND AMS1027 PIN FUNCTIONS Pin # Name Function Power Switch Output. SW is the drain of the internal MOSFET switch. Connect the power inductor and output rectifier to SW. SW can swing between GND and 22V. 1 SW 2 GND 3 FB Feedback Input. FB voltage is 1.25V. Connect a resistor divider to FB. 4 EN Regulator On/Off Control Input. A high input at EN turns on the converter, and a low input turns it off. When not used, connect EN to the input source for automatic startup. The EN pin cannot be left floating. 5 IN Input Supply Pin. Must be locally bypassed. Ground. ELECTRICAL CHARACTERISTICS VIN = VEN = 5V, TA = +25°C unless otherwise specified. Parameters Symbol Operating Input Voltage Condition VIN Min Typ 2.5 Undervoltage Lockout 2.25 Undervoltage Lockout Hysteresis 92 Max Units 6 V 2.45 V mV Supply Current (Shutdown) VEN = 0V 0.1 1 µA Supply Current (Quiescent) VFB = 1.3V 635 850 µA 1.0 1.3 1.5 MHz Switching Frequency fSW Maximum Duty Cycle VFB = 0V 85 92 EN Threshold VEN Rising 1.1 1.35 EN Threshold VEN Rising, VIN = 2.5V 0.8 EN Hysteresis VEN = 0V, 5V EN Input Bias Current FB Voltage VFB FB Input Bias Current SW On-Resistance VFB = 1.25V 1.6 V V 90 mV 1 µA 1.21 1.25 –100 –30 nA 0.5 Ω 1.9 A RDS (ON) SW Current Limit SW Leakage % VSW = 15V Thermal Shutdown 1 160 3 Advanced Monolithic Systems http://www.ams-semitech.com 1.29 V µA °C AMS1027 TYPICAL APPLICATION CIRCUITS V IN = 5V, VOUT = 12V, IOUT = 200mA Boost Circuit D1 MBR0520L VIN 5V 5 OFF ON 4 2 IN EN 1 C3 100pF SW AMS1027 GND VOUT 12V 200mA FB 3 4 Advanced Monolithic Systems http://www.ams-semitech.com AMS1027 PACKAGE INFORMATION SOT23-5 2.80 3.00 5 4 1.50 1.70 2.60 3.00 0.09 0.20 SIDE VIEW 1 3 TOP VIEW 0.84 0.90 1.00 MAX SEATING PLANE 0.30 0.50 0.95 BSC 0.00 0.10 NOTE: FRONT VIEW ALL DIMENSIONS ARE IN MILLIMETERS. 5 Advanced Monolithic Systems http://www.ams-semitech.com