UNISONIC TECHNOLOGIES CO., LTD UC3551 Preliminary CMOS IC ADVANCED PWM STEP-UP DC-DC CONVERTER DESCRIPTION The UTC UC3551 is a step-up DC/DC converter with high efficiency and low start-up voltage. It is operaded in stable waveforms without external compensate. This device incorporates an adaptive current mode PWM control loop in which an error amplifier, ramp generator, comparator, switch pass element and driver are included. Besides, this circuit provides a stable and high efficient operation over a wide range of load currents. The UTC UC3551 features high switching rate which is up to 450 KHz, making the external component counts less required. Moreover, it features 17μA low quiescent current, which makes the battery life longer. The low start-up input voltage below 1V makes UTC UC3551 suitable for 1 to 4 battery cells applications of providing up to 300mA output current. Two external resistors determine the value of the output voltage. The external power devices (NMOS or NPN) are derived by both internal 2A switch and driver. The UTC UC3551 is intended to be used in PDA, DSC, LCD Panel, RF-Tags, MP3, portable instrument and wireless equipment. FEATURES * Low Start-up Input Voltage is as Low as 1.0V * Efficiency up to 90% * High Supply Capability to Deliver 3.3V 100mA with 1 Alkaline Cell * Quiescent (Switch-off) Supply Current: 17µA * Zero Shutdown Mode Supply Current * Fixed Switching Frequency: 450KHz * Both Internal and External Power Switches for Maximum Flexibility ORDERING INFORMATION Ordering Number Lead Free Halogen Free UC3551L-AG6-R UC3551G-AG6-R UC3551L-AG6-R Package Packing SOT-26 Tape Reel (1)Packing Type (1) R: Tape Reel (2)Package Type (2) AG6: SOT-26 (3)Lead Free (3) G: Halogen Free, L: Lead Free www.unisonic.com.tw Copyright © 2011 Unisonic Technologies Co., Ltd 1 of 6 QW-R502-555.a UC3551 Preliminary CMOS IC MARKING INFORMATION PACKAGE VOLTAGE CODE SOT-26 AD:ADJ PIN CONFIGURATION PIN DESCRIPTION PIN NO. 1 2 3 4 5 6 PIN NAME CE EXT GND LX VDD FB MARKING DESCRIPTION Chip enable UC3551 gets into shutdown mode when CE pin set to low. Output pin for driving external NMOS Ground Pin for switching Input positive power pin of UC3551 Feedback input pin Internal reference voltage for the error amplifier is 1.25V. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 2 of 6 QW-R502-555.a UC3551 Preliminary CMOS IC BLOCK DIAGRAM VLx Limiter LX Vref VDD Buffer + Control Circuit GND Chip Enable EXT - FB Over Temp Detector EN UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 3 of 6 QW-R502-555.a UC3551 Preliminary CMOS IC ABSOLUTE MAXIMUM RATING PARAMETER SYMBOL RATINGS UNIT Supply Voltage VIN − 0.3 ~ 7 V LX Pin Switch Voltage VLX − 0.3 ~ (VDD + 0.8) V Other I/O Pin Voltages − 0.3 ~ (VDD + 0.3) V LX Pin Switch Current ILX 2.5 A EXT Pin Driver Current IEXT 200 mA Operating Junction Temperature TOPR 125 °C Storage Temperature TSTG -65~+150 °C Notes: Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. THERMAL DATA PARAMETER SYMBOL θJC Junction to Case RATINGS 145 UNIT °C/W ELECTRICAL CHARACTERISTICS (TA = 25°C,VIN = 1.5V, VDD= 3.3V, Load Current = 0, unless otherwise specified) PARAMETER SYMBOL CONDITIONS Start-UP Voltage VST IL = 1mA Operating VDD Range VDD VDD pin voltage MIN 2 TYP 0.98 MAX 1.05 6.5 (Note ) UNIT V V No Load Current I (VIN) INO LOAD VIN = 1.5V, VOUT = 3.3V 75 μA Switch-off Current I (VDD) ISWITCH OFF VIN = 6V 17 μA Shutdown Current I (VIN) IOFF CE Pin = 0V, VIN = 4.5V 0.01 1 μA Feedback Reference Voltage VREF Close Loop, VDD = 3.3V 1.225 1.25 1.275 V Switching Frequency FS VDD = 3.3V 450 KHz Maximum Duty DMAX VDD = 3.3V 95 % LX ON Resistance VDD = 3.3V 0.3 Ω Current Limit Setting ILIMIT VDD = 3.3V 2 A EXT ON Resistance to VDD VDD = 3.3V 5 Ω EXT ON Resistance to GND VDD = 3.3V 5 Ω Line Regulation ∆VLINE VIN = 1.5 ~ 2.5V, IL = 1mA 10 mV/V Load Regulation ∆VLOAD VIN = 2.5V, IL = 1 ~ 100mA 0.25 mV/mA CE Pin Trip Level VDD = 3.3V 0.4 0.8 1.2 V Temperature Stability for Vout Ts 50 ppm/°C Thermal Shutdown TSD 165 °C Thermal Shutdown Hysterises ∆TSD 10 °C Note: The CE pin shall be tied to VDD pin and inhibit to act the ON/OFF state whenever the VDD pin voltage may reach to 5.5V or above. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 4 of 6 QW-R502-555.a UC3551 Preliminary CMOS IC TEST CIRCUIT D1 L1 VIN CIN 100µF VOUT C2 1µF D1N5819 COUT 100µF VDD EN LX 3.3~10µH C1 102 UTC UC3551 FB EXT EXT R2 1M GND R1 3M TYPICAL APPLICATION CIRCUIT D1 L1 VIN CIN 100µF VOUT C2 1µF D1N5819 COUT 100µF VDD EN LX 3.3~10µH C1 102 R1 3M UTC UC3551 FB EXT EXT R2 1M GND D1 L1 VIN CIN 100µF VOUT C2 1µF D1N5819 COUT 100µF VDD EN LX 3.3~10µH C1 102 R1 3M UTC UC3551 M1 FB EXT NMOS GND UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw R2 1M 5 of 6 QW-R502-555.a UC3551 Preliminary CMOS IC UTC assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all UTC products described or contained herein. UTC products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 6 of 6 QW-R502-555.a