MT3608L

MT3608L 2.5A,High Efficiency 1.2MHz Current Mode Step-Up Converter FEATURES ⚫ ⚫ ⚫ ⚫ ⚫ ⚫ ⚫ ⚫ ⚫ ⚫ ⚫ ⚫ GENERAL DESCRIPTION Integrated 80mΩ Power MOSFET 2.2V to 16V Input Voltage 1.2MHz Fixed Switching Frequency Adjustable Over Current Protection: 0.5A ~2.5A Internal 2.5A Switch Current Limit(OC pin floating) Adjustable Output Voltage Internal Compensation Over Voltage Protection Up to 16V Output Voltage Automatic Pulse Frequency Modulation Mode at Light Loads up to 93% Efficiency Available in a 6-Pin SOT23-6 Package The MT3608L is a constant frequency, 6-pin SOT23 current mode step-up converter intended for small, low power applications. The MT3608L switches at 1.2MHz 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 MT3608L features automatic shifting to pulse frequency modulation mode at light loads. The MT3608L includes under-voltage lockout, current limiting, and thermal overload protection to prevent damage in the event of an output overload. The MT3608L is available in a small 6-pin SOT-23 package. APPLICATIONS ⚫ ⚫ ⚫ ⚫ ⚫ Battery-Powered Equipment Set-Top Boxed LCD Bais Supply DSL and Cable Modems and Routers Networking cards powered from PCI or PCI express slots TYPICAL APPLICATION 4.7μH D SW MT3608L R1 110k 1% L VIN VIN CIN 22μF EN COUT 22μF FB OC RSET VOUT=5V GND R2 15k 1% Figure 1. Basic Application Circuit www.aerosemi.com Aerosemi Proprietary Information.Unauthorized Photocopy and Duplication Prohibited. All Rights Reserved. 1 AEROSEMI MT3608L 2.5A,High Efficiency,1.2MHz Step-Up Converter ABSOLUTE MAXIMUM RATINGS (Note 1) VIN,EN voltages……………………-0.3V to 18V FB, Voltages………………...............-0.3V to 6V SW Voltage………………………...-0.3V to 22V Power Dissipation………………………...0.6W Thermal Resistance θJC………………..130°C/W Thermal Resistance θJA………………..250°C/W Junction Temperature(Note2)………..........160°C Operating Temperature Range…….-40°C to 85°C Lead Temperature(Soldering,10s)………...300°C Storage Temperature Range……..-65°C to 150°C ESD HBM(Human Body Mode)……………...2kV ESD MM(Machine Mode)………………….200V PACKAGE/ORDER INFORMATION Order Part Number Package Top Marking MT3608L SOT23-6 B628 TOP VIEW SW 1 6 OC GND 2 5 VIN FB 3 4 EN 6-LEAD PLASTIC SOT-23 TJMAX = 160°C, θJA = 250°C/ W, θJC = 130°C/W PIN DESCRIPTION Pin Name Pin Number SW 1 GND 2 FB 3 EN 4 VIN OC 5 6 Description 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. Ground Pin Feedback Input. The FB voltage is 0.6V. Connect a resistor divider to FB. 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 supply for automatic startup. Input Supply Pin. Must be locally bypassed. Adjustable Current Limit (Floating Available). www.aerosemi.com Aerosemi Proprietary Information.Unauthorized Photocopy and Duplication Prohibited. All Rights Reserved. 2 AEROSEMI MT3608L 2.5A,High Efficiency,1.2MHz Step-Up Converter ELECTRICAL CHARACTERISTICS (Note 3) (VIN=VEN=5V,TA = 25°C, unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNIT Operating Input Voltage 2.2 16 V Under Voltage Lockout 2.2 V Under Voltage Lockout 100 mV Hysteresis Current (Shutdown) VEN= 0V 0.1 1 µA Quiescent Current (PFM) VFB=0.7V，No switch 100 200 µA Quiescent Current VFB=0.5V，switch 0.4 1.0 1.5 mA (PWM) Switching Frequency 1.2 MHz Maximum Duty Cycle VFB = 0V 90 % EN Input High Voltage 1.5 V EN Input Low Voltage 0.6 V OVP with Output 20 V FB Voltage 0.588 0.6 0.612 V FB Input Bias Current VFB = 0.6V -50 -10 nA SW On Resistance 80 150 mΩ VIN= 5V, Duty cycle=50%,OC SW Current Limit 2.5 A floating Adjustable OCP Current With External Resistor:19k~96k 0.5 2.5 A SW Leakage VSW = 20V 1 μA Thermal Shutdown 160 ℃ Thermal Shutdown 25 ℃ Hysteresis Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: TJ is calculated from the ambient temperature TA and power dissipation PD according to the following formula: TJ = TA + (PD) x (250°C/W). Note 3: 100% production test at 25°C. Specifications over the temperature range are guaranteed by design and characterization. www.aerosemi.com Aerosemi Proprietary Information.Unauthorized Photocopy and Duplication Prohibited. All Rights Reserved. 3 AEROSEMI MT3608L 2.5A,High Efficiency,1.2MHz Step-Up Converter TYPICAL PERFORMANCE CHARACTERISTICS VIN=3.7V,VOUT=5V,ILOAD=0.5A VIN=3.7V VOUT=5V ILOAD=1A www.aerosemi.com Aerosemi Proprietary Information.Unauthorized Photocopy and Duplication Prohibited. All Rights Reserved. 4 AEROSEMI MT3608L 2.5A,High Efficiency,1.2MHz Step-Up Converter VIN=5V,VOUT=12V,ILOAD=0.2A VIN=5V,VOUT=12V,ILOAD=0.5A FUNCTIONAL BLOCK DIAGRAM EN Shutdown Circuitry FB SW OC Adjustable Current Limit - 19KΩ~ 96KΩ 2.5A ~ 0.5A OVP Error Amplifier PWM Compartor + M1 Control Logic + VREF Current Sense Compartor + + VIN UVLO OSC GND Figure 2. MT3608L Block Diagram www.aerosemi.com Aerosemi Proprietary Information.Unauthorized Photocopy and Duplication Prohibited. All Rights Reserved. 5 AEROSEMI MT3608L 2.5A,High Efficiency,1.2MHz Step-Up Converter FUNCTIONAL DESCRIPTION Overview The MT3608L uses a fixed frequency, peak current mode boost regulator architecture to regulate voltage at the feedback pin. The operation of the MT3608L can be understood by referring to the block diagram of Figure 2. At the start of each oscillator cycle the MOSFET is turned on through the control circuitry. To prevent subharmonic oscillations at duty cycles greater 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 version of the difference between the 0.6V bandgap reference voltage and the feedback voltage. In this way the peak current level keeps the output in regulation. If the feedback voltage starts to drop, the output of the error amplifier increases. These results in more current to flow through the power MOSFET, thus increasing the power delivered to the output. The MT3608L has internal soft start to limit the amount of input current at startup and to also limit the amount of overshoot on the output. Current Limit Program A resistor between OC and GND pin programs peak switch current. The resistor value should be between 19k and 96k. The current limit will be set from 2.5A to 0.5A. Keep traces at this pin as short as possible. The OC pin can be floating, the current limit will be set by Internal 2.5A current limit. To set the over current trip point according to the following equation: IOCP=48000/R3 Over Voltage Protection (OVP) In some condition, the resistive divider may be unconnected, which will cause PWM signal to operate with maximum duty cycle and output voltage is boosted higher and higher. The power MOSFET will be turned off immediately, when the output voltage exceeds the OVP threshold level. The MT3608L’s OVP threshold is 20V. APPLICATIONS INFORMATION Setting the Output Voltage The internal reference VREF is 0.6V (Typical).The output voltage is divided by a resistor divider,R1 and R2 to the FB pin. The output voltage is given by  R  VOUT = VREF   1 + 1   R2  Inductor Selection The recommended values of inductor are 4.7 to 22μH. Small size and better efficiency are the major concerns for portable device, such as MT3608L used for mobile phone. The inductor should have low core loss at 1.2MHz and low DCR for better efficiency. To avoid inductor saturation current rating should be considered. Capacitor Selection Input and output ceramic capacitors of 22μF are recommended for MT3608L applications. For better voltage filtering, ceramic capacitors with low ESR are recommended. X5R and X7R types are suitable because of their wider voltage and temperature ranges. Diode Selection Schottky diode is a good choice for MT3608L because of its low forward voltage drop and fast www.aerosemi.com Aerosemi Proprietary Information.Unauthorized Photocopy and Duplication Prohibited. All Rights Reserved. 6 AEROSEMI MT3608L 2.5A,High Efficiency,1.2MHz Step-Up Converter reverses recovery. Using Schottky diode can get better efficiency. The high speed rectification is also a good characteristic of Schottky diode for high switching frequency. Current rating of the diode must meet the root mean square of the peak current and output average current multiplication as following ID (RMS)  IOUT  IPEAK The diode’ s reverse breakdown voltage should be larger than the output voltage. short and wide. ➢ SW node of DC-DC converter is with high frequency voltage swing. It should be kept at a small area. ➢ Place the feedback components as close as possible to the IC and keep away from the noisy devices. VOUT D VIA TO GND COUT R3 PIN1 GND Layout Consideration For best performance of the MT3608L, the following guidelines must be strictly followed. ➢ Input and Output capacitors should be placed close to the IC and connected to ground plane to reduce noise coupling. ➢ The GND should be connected to a strong ground plane for heat sinking and noise protection. ➢ Keep the main current traces as possible as VIN L MT3608L R2 VIA TO VOUT CIN R1 Red Trace should be as short as possible Figure 3. MT3608L Suggested Layout www.aerosemi.com Aerosemi Proprietary Information.Unauthorized Photocopy and Duplication Prohibited. All Rights Reserved. 7 AEROSEMI MT3608L 2.5A,High Efficiency,1.2MHz Step-Up Converter PACKAGE DESCRIPTION SOT23-6 2.80 3.00 0.95 BSC 0.60 TYP 1.20 TYP EXAMPLE TOP MARK AAAA . 1.50 1.70 2.60 TYP 2.60 3.00 PIN 1 TOP VIEW RECOMMENDED SOLDER PAD LAYOUT GAUGE PLANE 0.25 BSC 0.90 1.30 1.45 MAX SEATING PLANE 0.30 0.50 0.95 BSC 0.00 0.15 FRONT VIEW 0°~8° 0.30 0.55 0.09 0.20 SIDE VIEW NOTE: 1.DIMENSIONS ARE IN MILLIMETERS. 2.DRAWING NOT TO SCALE. 3.DIMENSIONS ARE INCLUSIVE OF PLATING. 4.DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR. www.aerosemi.com Aerosemi Proprietary Information.Unauthorized Photocopy and Duplication Prohibited. All Rights Reserved. 8 AEROSEMI MT3608L 2.5A,High Efficiency,1.2MHz Step-Up Converter IMPORTANT NOTICE Xi’an Aerosemi Technology Co.,Ltd reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services. Xi’an Aerosemi Technology Co.,Ltd is not responsible or liable for such altered documentation. Information of third parties may be subject to additional restrictions. Xi’an Aerosemi Technology Co.,Ltd does not assume any responsibility for use of any its products for any particular purpose, nor does Xi’an Aerosemi Technology Co.,Ltd assume any liability arising out of the application or use of any its products or circuits. Copyright © 2011, Xi’an Aerosemi Technology Co.,Ltd Http://www.aerosemi.com www.aerosemi.com Aerosemi Proprietary Information.Unauthorized Photocopy and Duplication Prohibited. All Rights Reserved. 9