MP7748SGF-Z

MP2012 Low Voltage, 2.7-6V Input,1.5A, 1.2MHz Synchronous Step-Down Converter EC R NE O EF W M ER D ME E N TO SI D ED G M N P2 S FO 15 R 2 The Future of Analog IC Technology DESCRIPTION FEATURES The MP2012 is a fully integrated, internally compensated 1.2MHz fixed frequency PWM step-down converter. It is ideal for powering portable equipment that runs from a single cell Lithium-Ion (Li+) Battery, with an input range from 2.7V to 6V. The MP2012 can provide up to 1.5A of load current with output voltage as low as 0.8V. It can also operate at 100% duty cycle for low dropout applications. With peak current mode control and internal compensation, the MP2012 is stable with ceramic capacitors and small inductors. Fault condition protection includes cycle-by-cycle current limiting and thermal shutdown. • • • • • MP2012 is available in a small QFN6 (3x3mm) package. • • • • • • 2.7-6V Input Operation Range Output Adjustable from 0.8V to VIN 1μA Max Shutdown Current. Up to 95% Efficiency 100% Duty Cycle for Low Dropout Applications 1.2MHz Fixed Switching Frequency Stable with Low ESR Output Ceramic Capacitors Thermal Shutdown Cycle-by-Cycle Over Current Protection Short Circuit Protection Available in QFN6 (3x3mm) APPLICATIONS • • • • • DVD+/-RW Drives Smart Phones PDAs Digital Cameras Portable Instruments For MPS green status, please visit MPS website under Quality Assurance. R “MPS” and “The Future of Analog IC Technology” are Trademarks of Monolithic Power Systems, Inc. N VIN 2.7V to 6V Efficiency vs. Load Current 100 4 5 C1 PVIN VIN EN MP2012 SW EN 6 3 90 VOUT 1.8V/1.5A L1 R1 2 GND FB 1 Rt C2 R2 80 EFFICIENCY (%) O T TYPICAL APPLICATION Vin=5V 70 Vin=3V 60 50 40 30 20 10 0 0 0.3 0.6 0.9 1.2 1.5 LOAD CURRENT(A) MP2012 Rev. 1.01 9/22/2011 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 1 MP2012 – 1.5A SYNCHRONOUS STEP-DOWN CONVERTER ORDERING INFORMATION Package Top Marking Free Air Temperature (TA) EC R NE O EF W M ER D ME E N TO SI D ED G M N P2 S FO 15 R 2 Part Number* MP2012DQ QFN6(3x3mm) 9E –40°C to +85°C * For Tape & Reel, add suffix –Z (e.g. MP2012DQ–Z). For RoHS compliant packaging, add suffix –LF (e.g. MP2012DQ–LF–Z) PACKAGE REFERENCE TOP VIEW FB 1 6 EN GND 2 5 VIN SW 3 4 PVIN Exposed Pad Connected to GND Thermal Resistance PVIN, VIN to GND......................–0.3V to + 6.5V SW to GND .......................... –0.3V to VIN + 0.3V EN, FB to GND ...........................–0.3V to +6.5V Operating Temperature............. –40°C to +85°C (2) Continuous Power Dissipation (TA = +25°C) ………………………………………………....2.5W Junction Temperature ...............................150°C Lead Temperature ....................................260°C Storage Temperature ............. –65°C to +150°C QFN6 (3x3mm) .......................50 ...... 12 ... °C/W R ABSOLUTE MAXIMUM RATINGS (1) Recommended Operating Conditions (3) N O T Supply Voltage VIN .............................2.7V to 6V Operating Junct. Temp (TJ)..... –40°C to +125°C MP2012 Rev. 1.01 9/22/2011 (4) θJA θJC 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. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 2 MP2012 – 1.5A SYNCHRONOUS STEP-DOWN CONVERTER ELECTRICAL CHARACTERISTICS (5) EC R NE O EF W M ER D ME E N TO SI D ED G M N P2 S FO 15 R 2 VIN = VEN = 3.6V, TA = +25°C, unless otherwise noted. Parameters Condition Supply Current VEN_= VIN, VFB = 0.9V Shutdown Current Thermal Shutdown Trip Threshold EN Trip Threshold EN Input Current EN Input Current IN Undervoltage Lockout Threshold IN Undervoltage Lockout Hysteresis VEN_= 0V, VIN = 6V Hysteresis = 20°C -40°C ≤ TA ≤ +85°C VEN = 0V VEN = 6V Rising Edge Regulated FB Voltage FB Input Bias Current SW PFET On Resistance SW NFET On Resistance SW Leakage Current SW Leakage Current SW PFET Peak Current Limit Switching Frequency TA = +25°C -40°C≤ TA≤ +85°C VFB = 0.8V ISW = 100mA ISW = -100mA VEN=0V; VIN=6V VSW_=0V VEN=0V; VIN=6V VSW_=6V Duty Cycle=100% Duty Cycle=50%(6) Min Typ Max Units 600 750 μA 1 μA °C V μA μA V mV 0.784 0.776 -50 0.18 0.14 0.01 150 1.0 0.1 6 2.40 160 0.800 0.800 -2 0.25 0.2 0.816 0.824 +50 0.28 0.24 nA Ω Ω -1 0.1 1 μA -5 1.5 5 μA 0.3 2.15 2.1 1.0 3.0 3.5 1.2 1.5 1.0 2.65 V A 1.4 MHz Notes: 5) Production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization. PIN FUNCTIONS Pin # Feedback input. An external resistor divider from the output to GND, tapped to the FB pin sets the output voltage. GND, Exposed Pad Ground pin. Connect exposed pad to ground plane for proper thermal performance. SW PVIN VIN EN Switch node to the inductor. Input supply pin for power FET. Input Supply pin for controller. Put small decoupling ceramic near this pin. Enable input, “High” enables MP2012. EN is pulled to GND with 1Meg internal resistor. T 2 N O 3 4 5 6 Description FB R 1 Name MP2012 Rev. 1.01 9/22/2011 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 3 MP2012 – 1.5A SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS EC R NE O EF W M ER D ME E N TO SI D ED G M N P2 S FO 15 R 2 VIN = 5V, VOUT = 1.8V, L=3.3uH, TA = +25ºC, unless otherwise noted. 100 90 Vin=5V 70 Vin=3V 60 50 40 30 20 10 0 0 0.3 0.6 0.9 1.2 850 35 800 30 750 25 700 20 650 15 600 10 550 5 500 2.5 1.5 3 3.5 LOAD CURRENT(A) Load Regulation 5.5 0 0 6 Vin=3V -0.1% -0.2% 4.5 4 0.20% Io=0A 0.00% Io=0.75A -0.20% Vin=5V Io=1.5A -0.40% -0.3% 0 0.5 1 -0.60% 3.5 3 2.5 2 2 2.5 3 3.5 4 4.5 5 5.5 INPUT VOLTAGE (V) 6 1.5 40% 50% 60% 70% 80% 90% 100% DUTY CYCLE N O T R LOAD CURRENT(A) 1.5 0.5 1 1.5 OUTPUT CURRENT (A) Peak Current vs. Duty 0.40% 0.0% -0.4% 5 Line Regulation LINE REGULATION LOAD REGULATION 0.1% 4 4.5 V IN(V) PEAK CURRENT(A) EFFICIENCY (%) 80 Case Tem perature Risevs. Output Current Enable Supply Current vs. Input Voltage Efficiency vs. Load Current MP2012 Rev. 1.01 9/22/2011 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 4 MP2012 – 1.5A SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS VOUT 2V/div SW 2V/div VIN 10V/div IINDUCTOR 2A/div EC R NE O EF W M ER D ME E N TO SI D ED G M N P2 S FO 15 R 2 VIN = 5V, VOUT = 1.8V, L=3.3uH, TA = +25ºC, unless otherwise noted. Short Entry Short Recovery Full Load No Load VOUT 1V/div VOUT 1V/div SW 5V/div SW 5V/div VIN 10V/div VIN 5V/div IINDUCTOR 2A/div IINDUCTOR 1A/div Power Up with 1.5A Load VOUT 1V/div SW 5V/div VIN 5V/div VOUT 1V/div VOUT 1V/div SW 5V/div SW 5V/div EN 2V/div EN 2V/div IINDUCTOR 1A/div IINDUCTOR 1A/div VOUT 20mV/div T O N SW 2V/div VOUT 20mV/div SW 2V/div IINDUCTOR 2A/div 400ns/div MP2012 Rev. 1.01 9/22/2011 Load Transient Response IOUT=0.75A-1.5A Step @ 1A/us Output Ripple Voltage Input Ripple Voltage VIN 50mV/div EN Start up with 1.5A Load EN Start Up without Load R IINDUCTOR 1A/div Power Up without Load IOUT 500mA/div 400ns/div 400us/div www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 5 MP2012 – 1.5A SYNCHRONOUS STEP-DOWN CONVERTER EC R NE O EF W M ER D ME E N TO SI D ED G M N P2 S FO 15 R 2 FUNCTION BLOCK DIAGRAM N O T R Figure 1―Function Block Diagram MP2012 Rev. 1.01 9/22/2011 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 6 MP2012 – 1.5A SYNCHRONOUS STEP-DOWN CONVERTER OPERATION The steady state duty cycle D for this mode can be calculated as: D = TON × fOSC × 100% ≈ VOUT × 100% VIN Where TON is the main switch on time and fOSC is the oscillator frequency (1.2MHz typ.). Current Mode PWM Control T R Slope compensated current mode PWM control provides stable switching and cycle-by-cycle current limiting for superior load and line response as well as protection of the internal main switch and synchronous rectifier. The MP2012 switches at a constant frequency (1.2MHz) and modulates the inductor peak current to regulate the output voltage. Specifically, for each cycle the PWM controller forces the inductor peak current to an internal reference level derived from the feedback error voltage. At normal operation, the main switch is turned on at each rise edge of the internal oscillator, and remains on for a certain period of time to ramp up the inductor current. As soon as the inductor current reaches the reference level, the main switch is turned off and immediately the synchronous rectifier will be turned on to provide the inductor current. In forced PWM mode, the synchronous rectifier will stay on until the next oscillator cycle. O N Dropout Operation EC R NE O EF W M ER D ME E N TO SI D ED G M N P2 S FO 15 R 2 The MP2012 is a fixed frequency 1.2MHz current mode 1.5A step-down converter, optimized for low voltage, Li-Ion battery powered applications where high efficiency and small size are critical. MP2012 integrates a high side PFET main switch and a low side synchronous rectifier. It always operates in continuous conduction mode, simplifies the control scheme and eliminates the random spectrum noise due to discontinuous conduction mode. MP2012 Rev. 1.01 9/22/2011 The MP2012 allows the main switch to remain on for more than one switching cycle to increase the duty cycle when 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. In this case, the output voltage becomes the input voltage minus the voltage drop across the main switch and the inductor. Maximum Load Current The MP2012 can operate down to 2.5V input voltage; however the maximum load current decreases at lower input due to a 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. Short Circuit Protection When short circuit or over current condition happens, and FB is lower than about 0.3V, the MP2012 enters fold back mode. 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 approaches 0.8V. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 7 MP2012 – 1.5A SYNCHRONOUS STEP-DOWN CONVERTER APPLICATION INFORMATION R R 1 8 . 0 ⎞ ⎟ ⎠ 2 Cooper VOUT R1 Rt FB R2 Figure 2―Feedback Network Table 1 lists the recommended resistor value for common output voltages. Table 1—Resistor Selection vs. Output Voltage Setting R T O N VOUT × (VIN − VOUT ) VIN × ΔIL × fOSC Where ΔIL is inductor ripple current. Choose inductor ripple current approximately 30% of the maximum load current, 1.5A. The maximum inductor peak current is: IL(MAX ) = ILOAD MP2012 Rev. 1.01 9/22/2011 ΔI + L 2 = )⎛ T U O L= − 1 C Inductor Selection A 1μH to 10μH inductor with DC current rating at least 25% higher than the maximum load current is recommended for most applications. For best efficiency, the inductor DC resistance shall be