UNISONIC TECHNOLOGIES CO., LTD SR2803 LINEAR INTEGRATED CIRCUIT 330KHZ, 3A SYNCHRONOUS BUCK CONTROLLER DESCRIPTION The UTC SR2803 is a synchronous buck regulator. The device provides 3A of continuous load current over a wide input voltage of 4V~28V. Current mode control provides fast transient response and cycle by cycle current limit. Integrates soft start, and shutdown mode. The UTC SR2803 can provide low-ripple power, high efficiency, and perfect transient characteristics. The duty ratio varies linearly from 0% to 92% in the PWM control. The error amplifier circuit and soft-start circuit included in this device can prevent overshoot at startup. An enable function, an over current protect (OCP) function and short circuit protect (SCP) are also build inside, and when OCP happens, the operation frequency will be reduced. FEATURES * Input voltage varies from 4V ~ 28V * Output voltage varies from 0.8V to VCC * Duty ratio varies from 0% to 92% PWM control * With 330kHz typical oscillation frequency * Thermal shutdown and SCP function and soft-start, current limit, enable function * Low ESR output capacitor(Multi-layer chip capacitor) application ORDERING INFORMATION Ordering Number SR2803G-S08-R Package SOP-8 Packing Tape Reel MARKING www.unisonic.com.tw Copyright © 2015 Unisonic Technologies Co., Ltd 1 of 5 QW-R103-056.B SR2803 LINEAR INTEGRATED CIRCUIT PIN CONFIGURATION PIN DESCRIPTION PIN NO. 1 PIN NAME FB 2 EN 3 4 5 6 7 8 COMP VCC SW SW VSS VSS DESCRIPTION Feedback pin Power-off pin H: normal operation (Step-down) L: Step-down operation stopped (All circuits deactivated) Compensation pin IC power supply pin Switch pin. Connect external inductor here. Switch pin. Connect external inductor here. GND pin GND pin BLOCK DIAGRAM VCC EN Start Up REF_2.5V REF_0.8V FB EA Current Source Bias SENSE OSC SLOPE Driver PWM PWM LATCH Dead Time Control SW Driver SS COMP UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw GND 2 of 5 QW-R103-056.B SR2803 LINEAR INTEGRATED CIRCUIT ABSOLUTE MAXIMUM RATING (TA=25°C, unless otherwise specified) PARAMETER SYMBOL RATINGS UNIT VCC Pin Voltage VCC VSS -0.3 ~VSS +28 V Feedback Pin Voltage VFB VSS -0.3 ~ VCC V ON/OFF Pin Voltage VEN VSS - 0.3 ~ VCC+ 0.3 V Switch Pin Voltage VSW VSS - 0.3 ~ VCC+ 0.3 V Operating Supply Voltage VOP +4 ~ 28 V Power Dissipation PD Internally limited Storage Temperature TSTG -40 ~ +150 °C Operating Temperature TOPR -20 ~ +125 °C Note: 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 RATINGS UNIT Junction to Ambient θJA 70 °С/W Junction to Case θJC 25 °С/W Note: θJA is measured with the PCB copper area(need connect to SW pins) of approximately 1 in2(Multi-layer) ELECTRICAL CHARACTERISTICS (VIN = 12V, TA= 25°C, unless otherwise specified) PARAMETER Feedback Voltage Feedback Bias Current Switch Current Standby Current Quiescent Current Oscillation Frequency Frequency of Current Limit or Short Circuit Protect Line Regulation Load Regulation EN Pin Input Current Soft-Start Time Internal MOSFET RDS(ON) EN Pin Logic input threshold voltage Thermal shutdown Temp SYMBOL VFB IFB(BIAS) IQ fOSC TEST CONDITIONS IOUT=0.2A IOUT=0.1A Pear current, No outside circuit VFB=0V Force driver on VEN=0V No outside circuit VFB=0V Force driver on VFB=1.2V Force driver off Measure waveform at SW Pin fOSC1 Measure waveform at SW Pin ISW ISTN-BY ∆VOUT VOUT ∆VOUT VOUT ISH ISL TSS RDS(ON) VSH VSL TSD 3.5 A 2 10 μA 260 3 330 5 400 mA KHz 20 40 KHz VCC=5V-28V, IOUT=0.2A 0.4 % IOUT=0.2A-3A 0.3 % VEN=2.5V(ON) VEN=0.3V(OFF) 5 0 3.5 70 50 μA μA ms mΩ mΩ V V °C 0.3 High-side Switch, ISW=1A low-side Switch, ISW=1A High(regulator ON) Low(regulator OFF) UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw MIN TYP MAX UNIT 0.784 0.80 0.816 V 0.1 0.5 μA 8 1.6 0.8 150 3 of 5 QW-R103-056.B SR2803 LINEAR INTEGRATED CIRCUIT TYPICAL APPLICATION CIRCUIT MLCC FB VSS EN VSS COMP SW VCC SW 100k Co1 51P Rc 10k Co2 10n L4 5V/3A 10µH Cin 22µF + V5 - 12 Cout 22µF Rbf2 6.8K Rbf1 1.3K UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 4 of 5 QW-R103-056.B SR2803 LINEAR INTEGRATED CIRCUIT TYPICAL CHARACTERISTICS Short Protect SW Wave Short Protect SW Wave VIN=19V, VOUT=5V, ILOAD=3A VIN=19V, VOUT=0V 5V 5V 0 0 0 12.5 25 125 250 Time (25μs/div) Efficiency (%) Time (2.5μs/div) 0 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 5 of 5 QW-R103-056.B