SE3608

SE3608 2A/1.2Mhz Output Current, Boost Converter General Description Features The SE3608 is a high efficiency current-mode boost  Wide Input Range: 2.5-6V Input converter with a fixed operation frequency. The  Up to 1.5A Output Current SE3608 integrates a very low Rds-on NMOSFET to  Maximum 8V Output Voltage reduce power loss and achieve higher efficiency. The  1.2MHz Switching Frequency maximum efficiency is up to 93%. SE3608 can output  Low RDS(ON): 70mΩ 2A current when Vin is higher than 3.3V and output is  Up to 90% Efficiency 5V. The high 1.2MHz operation frequency minimizes L  Under-Voltage Lockout Protection and C value. The internal compensation network  Over-Temperature Protection reduces external component counts. Small foot print  Internal Soft Start SOT23-6 package provides the best solution for PCB  1uA Shutdown Current layout area.  Accurate Reference: 0.6V VREF  Compact package: SOT23-6 SE3608 is designed with 12V process. This allows SE3608 to be used in applications where higher voltage is needed, such as charging two Lithium Applications batteries in series. The other possible application  Chargers where the higher voltage is needed is Qualcomm  LCD Displays Quick Charge 2.0 compatible portable chargers.  Digital Cameras SE3608 can support 9V Vout for this application.  Handheld Devices  Portable Products Typical Application L1 2.2uH VIN CIN 22uF OFF/ON IN R1 440K EN FB VOUT CFB 22pF SW GND Rev1.0 Schottky R2 60K COUT1 22uF×2 COUT2 100 nF Preliminary and all contents are subject to change without prior notice. © Seaward Electronics, Inc., • www.seawardinc.com.cn • Page 1 9/4/2012 SE3608 2A/1.2Mhz Output Current, Boost Converter Pin Configuration Pin Description NO. Pin Name Pin Function Description 1 SW Power Switch Output. Connect the inductor and the blocking Schottky diode to SW. 2 GND 3 FB 4 EN 5 IN Input Supply Pin. Must be locally bypassed. 6 NC No Internal Connection GND Feedback Enable pin. A high input at EN enables the device and a low input disables the devices. When not used, connect EN to the input source for automatic startup. Functional Block Diagram SW VIN UVLO OTP Logic Control Internal Compensation +PWM - Internal Soft Start EN OVP EN Logic Currnet Sense Slope Compensation EA Driver - + Vref FB Rev1.0 GND Preliminary and all contents are subject to change without prior notice. © Seaward Electronics, Inc., • www.seawardinc.com.cn • Page 2 9/4/2012 SE3608 2A/1.2Mhz Output Current, Boost Converter Absolute Maximum Ratings Symbol Parameter Maximum Units VIN VIN Supply Voltage -0.3～6.5 V VSW Voltage at SW Pin -0.5～12 V VIO All Other I/O Pins GND-0.3 to VDD+0.3 V 220 ℃/W PTR1 Thermal Resistance(SOT23-6) ΘJA Tstg Storage Temperature -55 to 150 ℃ Tsolder Package Lead Soldering Temperature（10s） 260 ℃ ESD Susceptibility HBM(Human Body Mode) 2 kV Note: Exceeding these ratings may damage the device. Recommended Operating Conditions Symbol Parameter Maximum Units VIN Input Voltage 2.5 to 6 V VSW Output Voltage VIN to 10 V TA Ambient Temperature -40 to +85 ℃ TJ Junction Temperature -40 to +125 ℃ Note: The device is not guaranteed to function outside of its operating rating. Rev1.0 Preliminary and all contents are subject to change without prior notice. © Seaward Electronics, Inc., • www.seawardinc.com.cn • Page 3 9/4/2012 SE3608 2A/1.2Mhz Output Current, Boost Converter Electrical Characteristics （VIN = 3.3V, VOUT=5V, IOUT=100mA, TA = 25°C unless otherwise specified） Symbol Parameter VIN Input Voltage Conditions Min. Typ. 2.5 Max. Unit 6 V 600 612 mV 0.05 1 µA Feedback VFB Feedback Voltage 588 Ibias FB Pin Input Bias Current UVLO UVLO Under Voltage Lock Out 2.1 V Operating Current Ioff Operating Current（Shutdown） Isby No Switching Fsw Switching Frequency Dmax Maximum Duty Cycle 0.1 Vin=3V VFB=0.7V VFB=0V 1 µA 100 µA 1.2 MHz 90 % Chip Enable VEN_H EN Minimum High Level VEN_L EN Maximum Low Level VHYS EN Hysteresis IEN EN Input Bias Current 1.5 V 0.4 90 V mV 1 µA OTP OTP 120 ℃ OTP Hysteresis 20 ℃ Output Switch RON SW On Resistance (Note 3) 70 mΩ ILIMIT SW Current Limit 5 A ILEAK SW Leakage Current Vsw＝5V 0.01 1 µA Open Circuit Protection VOV SE3608 VOUT×112% V 400 µS Soft Start tss Soft Start Time (Note 3) VIN Power On Note3: Guaranteed by design. Rev1.0 Preliminary and all contents are subject to change without prior notice. © Seaward Electronics, Inc., • www.seawardinc.com.cn • Page 4 9/4/2012 SE3608 2A/1.2Mhz Output Current, Boost Converter Typical Performance Characteristics Current Load Vs Efficiency Current Load Vs Efficiency 93 94 92 92 Efficiency / % Efficiency / % 91 90 88 86 Vin=3.6V,Vout=5V 90 89 88 87 Vin=3.6V,Vout=5V 84 86 82 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 I Load / A Rev1.0 85 0 0.5 1 1.5 2 2.5 I Load / A Fig 1 Efficiency Vs Light Load Fig 2 Efficiency Vs Heavy Load Fig 3 Startup with Vin Fig 4 SW Waveform Fig 5 Transient Response Fig 6 Transient Response (VIN=3.6V, Vout=5V, Iload=0.9A to 0.15A) (VIN=3.6V, Vout=5V, Iload=0.15A to 0.9A) Fig 7 Vout Ripple Fig 8 Quiescent Current Vs Temperature Preliminary and all contents are subject to change without prior notice. © Seaward Electronics, Inc., • www.seawardinc.com.cn • Page 5 9/4/2012 SE3608 2A/1.2Mhz Output Current, Boost Converter Operation Description The SE3608 adopts a fixed frequency, peak current mode boost regulator architecture to regulate output voltage. The operating principle of the SE3608 can be easily understood by referring to the functional block diagram. At the beginning of each oscillator cycle the MOSFET is turned on by the control circuit. To prevent sub-harmonic oscillations at duty cycle larger than 50 percent, a stabilizing ramp is added to the output of the current sense amplifier and the result is fed into the negative input of the PWM comparator. When this voltage equals the output voltage of the error amplifier, the power MOSFET is turned off. The voltage at the output of the error amplifier is an amplified result of the difference between the 0.6V reference voltage and the feedback voltage. In this way the peak current level keeps the output voltage in regulation. If the feedback voltage starts to drop, the output of the error amplifier increases, resulting in more current to flow through the power MOSFET, thus increasing the power delivered to the output. The SE3608 has internal soft start to avoid rush input current during the startup and also to avoid overshoot on the output. Applications Information Because of the high integration in the SE3608, the application circuit based on this regulator IC is rather simple. Only input capacitor CIN, output capacitor COUT1 and COUT2, inductor L, Schottky diode and feedback resistors (R1 and R2) need to be selected for the targeted applications. Feedback Resistor Divider R1 and R2: R1 and R2 should be chosen to program the proper output voltage. To minimize the power consumption under light loads, it is desirable to choose large resistance values for both R1 and R2. A value of between 330KΩ and 5MΩ is recommended for both resistors. If R1=440KΩ is chosen, then R2 can be calculated to be 60 KΩ based on the following equation: R2 = (R1×0.6V)/(VOUT - 0.6V) Feedback Capacitor CFB: In order to enhance response speed of the convertor, feedback capacitor CFB should be added to the loop. Its value should not be less than 22pF. Input Capacitor CIN: To minimize the potential noise problem, place a typical X5R or better grade ceramic capacitor really close to the IN and GND pins. Care should be taken to minimize the loop area formed by CIN, and IN/GND pins. In this case a 10uF low ESR ceramic is recommended. Rev1.0 Preliminary and all contents are subject to change without prior notice. © Seaward Electronics, Inc., • www.seawardinc.com.cn • Page 6 9/4/2012 SE3608 2A/1.2Mhz Output Current, Boost Converter Output Capacitor COUT1 and COUT2: The output capacitor is selected to meet the output ripple noise requirements. Both steady state ripple and transient requirements must be taken into consideration when selecting these capacitors. For the best performance, it is recommended COUT1 should be X5R or better grade ceramic capacitor with 10V rating and more than two pieces of 22uF Capacitors. Only when COUT1 is big enough, it can absorb the energy of inductor and prevent the Vout to shoot up too high when there is a sudden reduction in the current load. It is recommended COUT2 is 100nF. It can also reduce the ripple of output voltage. Boost Inductor L: The recommended value of inductor is 1u H. Small size and better efficiency are the major concerns for portable devices. The inductor should have low core loss at 1.2MHz and low DCR for better efficiency. To avoid inductor saturation the current rating should be considered. Diode Selection: Schottky diode is a good choice for SE3608 because of its low forward voltage drop and fast reverses recovery in order to get better efficiency. The high speed rectification is also a good characteristic of Schottky diode for high switching frequency. The diode reverse breakdown voltage should be larger than the output voltage, and its forward voltage should be less than 0.6V. Start-up and Inrush Current: The SE3608 has internal soft start to limit the value of current through VIN during the startup and also to avoid overshoot on the output. The soft start is realized by gradually increasing the output of error amplify during start-up. Over Voltage Protection: The SE3608 has integrated over voltage protection function. If the output voltage exceeds the predetermined value of 12%, the internal circuit will shut power MOS, until VOUT voltage falls down. Rev1.0 Preliminary and all contents are subject to change without prior notice. © Seaward Electronics, Inc., • www.seawardinc.com.cn • Page 7 9/4/2012 SE3608 2A/1.2Mhz Output Current, Boost Converter Outline Drawing For SOT23-6 联系方式： 北京思旺电子技术有限公司–中国总部 地址：中国北京市海淀区信息路 22 号上地科技综合楼 B 座二层 邮编：100085 电话:010-82895700/1/5 传真:010-82895706 Seaward Electronics Corporation – 台湾办事处 2F, #181, Sec. 3, Minquan East Rd, Taipei, Taiwan R.O.C 电话: 886-2-2712-0307 传真: 886-2-2712-0191 Seaward Electronics Incorporated – 北美办事处 1512 Centre Pointe Dr. Milpitas, CA95035, USA 电话: 1-408-821-6600 Rev1.0 Preliminary and all contents are subject to change without prior notice. © Seaward Electronics, Inc., • www.seawardinc.com.cn • Page 8 9/4/2012