MP2128 2.5V-6V Input, 3MHz, 1A Synchronous Step-Down Converter The Future of Analog IC Technology DESCRIPTION FEATURES The MP2128 is a 3MHz constant frequency, current mode, PWM step-down converter with integrated main switch and synchronous rectifier that is ideal for powering portable equipment that runs from a single Li-Ion or LiPolymer battery. • • • • • • • • • • • • • The MP2128 can supply up to 1A load current from a 2.5V to 6V input voltage. The output voltage can be as low as 0.6V. Additional features include <1µA shutdown current, internal soft-start, cycle-by-cycle over current protection, short circuit protection, and thermal shutdown. The MP2128 is available in low profile (1.5mm) 5-pin SOT23 and 8-pin, QFN8 2mm×2mm packages. High Efficiency: Up to 95% 3MHz Constant Switching Frequency 1A Available Load Current 2.5V to 6V Input Voltage Range Output Voltage as Low as 0.6V Current Mode Control Cycle-by-Cycle Over Current Protection Short Circuit Protection Thermal Shutdown <1µA Shutdown Current Internal Soft-Start Space Saving 5-Pin SOT23 Package and 8-pin, QFN8 2mm×2mm package APPLICATIONS • • • • • • Cellular Phones Microprocessors and DSP Core Supplies PDAs and Smart Phones MP3 and Portable Media Players Digital Still and Video Cameras Portable Instruments “MPS” and “The Future of Analog IC Technology” are Registered Trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION U1 2.5V--6V VIN 3 SW IN SW 8 R1 200k 1% 7 FB EN NC VOUT 5 MP2128DG OFF ON 1.8V 1A 6 PGND 1 4 R2 100k 1% AGND 2 MP2128 Rev. 0.9 7/20/2009 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2009 MPS. All Rights Reserved. 1 MP2128 – 3MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER ORDERING INFORMATION Part Number* Package Top Marking Temperature MP2128DT Part Number** MP2128DG SOT23 Package QFN8(2mmx2mm) 2H Top Marking 2H –40°C to +85°C Temperature –40°C to +85°C * For Tape & Reel, add suffix –Z (eg. MP2128DT–Z). For RoHS Compliant Packaging, add suffix –LF (eg. MP2128DT–LF–Z) ** For Tape & Reel, add suffix –Z (eg. MP2128DG–Z). For RoHS Compliant Packaging, add suffix –LF (eg. MP2128DG–LF–Z) PACKAGE REFERENCE TOP VIEW 1 GND 2 SW MARKING EN 3 TOP VIEW 5 4 FB IN SOT23 IN to GND .................................. –0.3V to +6.5V SW to GND .......................... –0.3V to VIN + 0.3V FB, EN to GND ............................. –0.3V to +6.5V Continuous Power Dissipation. (TA = +25°C) (2) SOT23 ..................................................... 0.57W QFN8 (2mmx2mm) .................................... 2.5W Junction Temperature ...............................150°C Lead Temperature ....................................260°C Storage Temperature............... –65°C to +150°C (3) Supply Voltage VIN .............................2.5V to 6V Output Voltage VOUT ...........................0.6V to 6V Operating Temperature.............. –40°C to +85°C MP2128 Rev. 0.9 7/20/2009 1 8 EN AGND 2 7 NC IN 3 6 SW PGND 4 5 SW QFN8 ABSOLUTE MAXIMUM RATINGS (1) Recommended Operating Conditions FB Thermal Resistance (4) θJA θJC SOT23 ................................... 220 .... 110.. °C/W QFN8 (2mmx2mm) ................. 50 ...... 12... °C/W Notes: 1) Exceeding these ratings may damage the device. 2) The maximum allowable power dissipation is a function of the maximum junction temperature TJ (MAX), the junction-toambient thermal resistance θJA, and the ambient temperature TA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by PD (MAX) = (TJ (MAX)-TA)/θJA. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage. 3) The device is not guaranteed to function outside of its operating conditions. 4) Measured on JESD51-7, 4-layer PCB. www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2009 MPS. All Rights Reserved. 2 MP2128 – 3MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER ELECTRICAL CHARACTERISTICS (5) VIN = VEN = 3.6V, TA = +25°C, unless otherwise noted. Parameters Condition Supply Current VEN = VIN, VFB = 0.65V Shutdown Current VEN = 0V, VIN = 6V IN Under Voltage Lockout Threshold Rising Edge IN Under Voltage Lockout Hysteresis TA = +25°C Regulated FB Voltage –40°C ≤ TA ≤ +85°C FB Input Bias Current VFB = 0.65V PFET Current Limit Duty=100% PFET On-Resistance ISW = 100mA NFET On-Resistance ISW = –100mA VEN = 0V; VIN = 6V SW Leakage Current VSW = 0V or 6V EN High Threshold –40°C ≤ TA ≤ +85°C EN Low Threshold –40°C ≤ TA ≤ +85°C Internal Soft-Start Time Oscillator Frequency Thermal Shutdown Threshold Hysteresis=20°C Min Typ Max 350 1.8 0.582 0.576 -50 0.01 2.1 250 0.594 0.594 µA 1 2.3 0.606 0.612 50 µA V mV V V nA A mΩ mΩ 1 µA 1.5 200 150 –1 1.6 0.4 2.4 100 2.8 150 Units 3.2 V V µs MHz °C Note: 5) Production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization. MP2128 Rev. 0.9 7/20/2009 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2009 MPS. All Rights Reserved. 3 MP2128 – 3MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS VIN=6V, VOUT=1.8V, L=1.2µH, C2=10µF, TA=25°C, unless otherwise noted. Efficiency vs. Load Current Steady State Operation Steady State Operation IOUT=0A IOUT=1A 95 EFFICIENCY (%) 90 4.2V to 3.4V 85 VOUT/AC 20mV/div. VOUT/AC 20mV/div. VSW 5V/div. VSW 5V/div. IINDUCTOR 1A/div. IINDUCTOR 1A/div. 5V to 3.4V 3.3V to 1.8V 80 75 70 0 100 200 300 400 500 600 700 800 9001000 200ns/div. 200ns/div. LOAD CURRENT ( mA ) Start-up Through Enable Start-up Through Enable Power-down Through Enable IOUT=0A IOUT=1A IOUT=0A VEN 5V/div. VEN 5V/div. VEN 5V/div. VOUT 1V/div. VOUT 1V/div. VOUT 1V/div. VSW 5V/div. VSW 5V/div. VSW 5V/div. IINDUCTOR 1A/div. IINDUCTOR 1A/div. IINDUCTOR 1A/div. 2s/div. Power-down Through Enable Load Transient IOUT=1A Load Step: 100mA-400mA, VIN=4.2V, VOUT=3.4V VEN 5V/div. VOUT/AC 100mV/div. VOUT 1V/div. VOUT/AC 50mV/div. IINDUCTOR 200mA/div. VSW 5V/div. IINDUCTOR 1A/div. ILOAD 200mA/div. IINDUCTOR 500mA/div. 1ms/div. MP2128 Rev. 0.9 7/20/2009 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2009 MPS. All Rights Reserved. 4 MP2128 – 3MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER PIN FUNCTIONS SOT23 Pin # QFN Pin # Name 1 8 EN 2 2,4 GND 3 5,6 SW 4 3 IN 5 1 FB Description Regulator Enable Control Input. Drive EN above 1.6V to turn on the part. Drive EN below 0.4V to turn it off. Ground. Power Switch Output. Inductor connection to drains of the internal PFET and NFET switches. Supply Input. Bypass to GND with a 4.7µF or bigger value ceramic capacitor. Feedback Input. Connect FB to the center point of the external resistor divider. The regulated feedback voltage is 0.6V. FUNCTIONAL BLOCK DIAGRAM Figure 1— Functional Block Diagram MP2128 Rev. 0.9 7/20/2009 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2009 MPS. All Rights Reserved. 5 MP2128 – 3MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER FUNCTIONAL DESCRIPTION MP2128 is a 3MHz constant frequency, current mode, PWM step-down converter. The device integrates both a main switch and a synchronous rectifier, which provides high efficiency and eliminates an external Schottky diode. It is ideal for powering portable equipment that runs from a single Li-lon or Li-Polymer battery. The MP2128 can achieve 100% duty cycle. The duty cycle D of a step-down converter is defined as: D = TON × fOSC × 100% ≈ VOUT × 100% VIN Where, Ton: Main Switch ON time Fosc: Switching frequency (3MHz) Vout: Output voltage Vin: Input voltage Peak Current Mode PWM Control Slope compensated current mode PWM control provides stable switching and cycle-by-cycle current limit for superior load and line response and protection of the internal main switch and synchronous rectifier. The MP2128 switches at a constant frequency (3MHz) and regulates the output voltage. During each cycle the PWM comparator modulates the power transferred to the load by changing the inductor peak current based on the feedback error voltage. During normal operation, the main switch is turned on for a certain time to ramp the inductor current at each rising edge of the internal oscillator, and switched off when the peak inductor current is above the error voltage. When the main switch is off, the synchronous rectifier will be turned on immediately and stay on until the next cycle starts. Short Circuit Protection The MP2128 has short circuit protection. When the output is shorted to ground, the oscillator frequency is reduced to prevent the inductor current from increasing beyond the PFET current limit. The PFET current limit is also reduced to lower the short-circuit current. The frequency and current limit will return to the normal values once the short circuit condition is removed and the feedback voltage reaches 0.6V. Maximum Load current The MP2128 can operate down to 2.5V input voltage, however the maximum load current decreases at lower input due to large IR drop on the main switch and synchronous rectifier. The slope compensation signal reduces the peak inductor current as a function of the duty cycle to prevent sub-harmonic oscillations at duty cycles greater than 50%. Conversely the current limit increases as the duty cycle decreases. Dropout Operation The MP2128 allows the main switch to remain on for more than one switching cycle and increases the duty cycle while the input voltage is dropping close to the output voltage. When the duty cycle reaches 100%, the main switch is held on continuously to deliver current to the output up to the PFET current limit. The output voltage then is the input voltage minus the voltage drop across the main switch and the inductor. MP2128 Rev. 0.9 7/20/2009 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2009 MPS. All Rights Reserved. 6 MP2128 – 3MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER PACKAGE INFORMATION SOT23 0.95 BSC 0.60 TYP 2.80 3.00 5 4 1.20 TYP 1.50 1.70 1 2.60 TYP 2.60 3.00 3 TOP VIEW RECOMMENDED LAND PATTERN 0.90 1.30 1.45 MAX 0.09 0.20 SEATING PLANE 0.30 0.50 0.95 BSC 0.00 0.15 SEE DETAIL "A" FRONT VIEW SIDE VIEW NOTE: GAUGE PLANE 0.25 BSC 0.30 0.55 0o-8o DETAIL A MP2128 Rev. 0.9 7/20/2009 1) ALL DIMENSIONS ARE IN MILLIMETERS. 2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH, PROTRUSION OR GATE BURR. 3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSION. 4) LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.10 MILLIMETERS MAX. 5) DRAWING CONFORMS TO JEDEC MO-178, VARIATION AA. 6) DRAWING IS NOT TO SCALE. www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2009 MPS. All Rights Reserved. 7 MP2128 – 3MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER QFN8 (2mmX2mm) PIN 1 ID MARKING 1.90 2.10 0.25 0.45 0.18 0.30 1.90 2.10 PIN 1 ID INDEX AREA PIN 1 ID SEE DETAIL A 0.45 0.65 8 1 1.05 1.25 0.50 BSC 5 TOP VIEW 4 BOTTOM VIEW 0.80 1.00 PIN 1 ID OPTION A R0.20 TYP. PIN 1 ID OPTION B R0.20 TYP. 0.20 REF 0.00 0.05 SIDE VIEW DETAIL A NOTE: 1.90 0.70 0.60 1) ALL DIMENSIONS ARE IN MILLIMETERS. 2) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH. 3) LEAD COPLANARITY SHALL BE 0.10 MILLIMETER MAX. 4) DRAWING CONFORMS TO JEDEC MO-229, VARIATION VCCD-3. 5) DRAWING IS NOT TO SCALE. 0.25 1.20 0.50 RECOMMENDED LAND PATTERN NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not assume any legal responsibility for any said applications. MP2128 Rev. 0.9 7/20/2009 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2009 MPS. All Rights Reserved. 8