MP28119 Ultra-small 1.7MHz, 600mA, Low-Voltage Synchronous Step-Down Converter The Future of Analog IC Technology DESCRIPTION FEATURES The MP28119 is a 1.7MHz constant frequency, current mode, ultra-small PWM step-down converter. The device integrates a main switch and a synchronous rectifier for high efficiency and eliminates the needs for an external schottky diode. It is ideal for powering portable equipment that runs from a single cell LithiumIon (Li+) battery. The MP28119 can supply 600mA of load current from a 2.5V to 6V input voltage. The output voltages of the MP28119EG-1.0 and MP28119EG-1.2 are fixed at 1.0V and 1.2V respectively. The MP28119 can also run at 100% duty cycle for low dropout applications. The MP28119 has an output discharge function that controls the discharging of the output capacitor. The MP28119 is available in an ultra-small 2x2 QFN package. High Efficiency: Up to 89% 1.7MHz Constant Switching Frequency 600mA Available Load Current 2.5V to 6V Input Voltage Range 100% Duty Cycle in Dropout Current Mode Control Short Circuit Protection Thermal Fault Protection Output Discharge Function <0.1μA Shutdown Current 1.0V and 1.2V Fixed Out-put Versions Ultra-Small 2x2 QFN Package APPLICATIONS Cellular and Smart Phones Microprocessors and DSP Core Supplies PDAs MP3 Players Digital Still and Video Cameras Portable Instruments For MPS green status, please visit MPS website under Quality Assurance. “MPS” and “The Future of Analog IC Technology” are Registered Trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION Efficiency vs. Load Current VOUT=1V, L=2.2uH IN SW 1 MP28119EG-1.0 OFF ON 4 EN GND 6,8 OUT 5 OUTPUT 90 Vin=3.3V EFFICIENCY (%) 7 100 80 70 60 Vin=5V 50 40 30 20 10 0 10 100 1000 LOAD CURRENT(mA) MP28119 Rev.0.91 www.MonolithicPower.com 11/23/2011 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 1 MP28119 – ULTRA-SMALL 1.7MHZ, 600MA LOW-VOLTAGE SYNCHRONOUS STEP-DOWN CONVERTER ORDERING INFORMATION Part Number VOUT MP28119EG-1.0 MP28119EG-1.2* MP28119EG* 1.0V 1.2V ADJ Package Temperature Top Marking 9K 2x2 QFN8 -20°C to +85°C 4Q * Contact factory for availability. ** MP28119EG-1.0 is fixed to 1V output, and MP28119EG-1.2 is fixed to 1.2V output. For RoHS Compliant Packaging, add suffix - LF (e.g. MP28119EG-LF); For Tape and Reel, add suffix -Z (e.g. MP28119EG-LF-Z). PACKAGE REFERENCE TOP VIEW TOP VIEW SW 1 8 GND SW 1 8 GND NC 2 7 IN NC 2 7 IN NC 3 6 GND NC 3 6 GND EN 4 5 FB EN 4 5 OUT EXPOSED PAD ON BACKSIDE CONNECT TO GND EXPOSED PAD ON BACKSIDE CONNECT TO GND External FB QFN8 (2mm x 2mm) Fixed Output QFN8 (2mm x 2mm) ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance VIN to GND ..................................–0.3V to +6.5V VSW to GND........................... –0.3V to VIN +0.3V VFB, VEN to GND ..........................–0.3V to +6.5V Junction Temperature .............................+150C Continuous Power Dissipation (TA = +25°C) (2) ............................................................. 1.5W Lead Temperature ..................................+260C Storage Temperature ............. –65C to +150C 2x2 QFN8................................80 ...... 16 ... C/W Recommended Operating Conditions (3) Supply Voltage VIN .............................2.5V to 6V Output Voltage VOUT ...........................0.6V to 6V Operating Temperature............. –20C to +85C (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 power dissipation at any ambient temperature is calculated using: 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 board. MP28119 Rev.0.91 www.MonolithicPower.com 11/23/2011 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 2 MP28119 – ULTRA-SMALL 1.7MHZ, 600MA LOW-VOLTAGE SYNCHRONOUS STEP-DOWN CONVERTER ELECTRICAL CHARACTERISTICS (5) (continued) VIN = VEN = 3.6V, TA = +25C, unless otherwise noted. Parameter Supply Current Shutdown Current IN Under Voltage Lockout Threshold IN Under Voltage Lockout Hysteresis Discharge MOSFET On Resistance Regulated FB Voltage Symbol Condition VEN = VIN, VFB = 0.51V VEN = 0V, VIN = 6V UVLO VFB FB Input Bias Current Regulated Output Voltage PFET On Resistance NFET On Resistance SW Leakage Current Rds(on)1 Rds(on)2 PFET Current Limit Rising Edge TA = +25°C, MP28119EG –20°C ≤ TA ≤ +85°C VFB = 0.65V, MP28119EG MP28119EG-1.0 IOUT = 50mA;–20°C ≤ TA ≤ +85°C MP28119EG-1.2 IOUT = 50mA;–20°C ≤ TA ≤ +85°C ISW = 100mA ISW = –100mA VEN = 0V,VIN = 6V, VSW = 0V or 6V Duty Cycle = 100%, Current Pulse Width < 1ms Min Typ 400 0.01 Max 600 1 Units μA μA 2.15 2.3 2.45 V 80 mV 100 Ω 0.588 0.582 –50 0.600 0.600 0.5 0.612 0.618 +50 0.97 1.000 1.03 V nA V 1.164 1.200 1.236 0.42 0.28 –1 0.8 1.6 +1 Ω Ω μA 2.4 A Oscillator Frequency Focs 1.7 MHz Minimum On Time Thermal Shutdown Trip Threshold Ton 100 ns 145 C EN Turn-onTrip Threshold –20°C ≤ TA ≤ +85°C EN Turn-off Trip Threshold EN Input Current –20°C ≤ TA ≤ +85°C VEN = 0V to 6V 0.3 –1 1.5 V +1 V μA Notes: 5) 100% production test at +25°C. Typical and temperature specifications are guaranteed by design and characterization. MP28119 Rev.0.91 www.MonolithicPower.com 11/23/2011 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 3 MP28119 – ULTRA-SMALL 1.7MHZ, 600MA LOW-VOLTAGE SYNCHRONOUS STEP-DOWN CONVERTER PIN FUNCTIONS Pin # Name 1 SW 2, 3 NC 4 EN FB 5 OUT 6, 8 7 GND, Exposed Pad IN Description Power Switch Output. Inductor connection to drains of the internal PFET and NFET switches. No Connection Regulator Enable Control Input. Drive EN above 1.5V to turn on the MP28119. Drive EN below 0.3V to turn it off (shutdown current < 0.1μA). Feedback Input (MP28119EG). Connect FB to the center point of the external resistor divider. The feedback threshold voltage is 0.6V. Output Voltage Sense Input (MP28119EG-1.0 and MP28119EG-1.2). An internal resistor divider is connected to this pin to set the proper output voltage. Ground. Connect exposed pad to GND plane for optimal thermal performance. Supply Input. Bypass to GND with a 2.2μF or greater ceramic capacitor. MP28119 Rev.0.91 www.MonolithicPower.com 11/23/2011 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 4 MP28119 – ULTRA-SMALL 1.7MHZ, 600MA LOW-VOLTAGE SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS Vin=5V, Vout=1V, L1=2.2uH, C1=4.7uF, C2=10uF, TA=25oC, tested on MP28119EG-1.0, unless otherwise noted. Output Voltage vs. Load Current Output Voltage vs. Supply Voltage VIN=5V IOUT=300mA 0.9985 0.998 0.9975 0.997 0.9965 0.996 0 100 200 300 400 500 600 LOAD CURRENT(mA) 0.9978 0.9976 0.9974 0.9972 0.997 IOUT=300mA OSCILLATOR FREQUENCY(MHz) 0.998 OUTPUT VOLTAGE(V) OUTPUT VOLTAGE(V) 0.999 Oscillator Frequency vs. Supply Voltage 2 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 2 2.5 3 3.5 4 4.5 5 5.5 6 SUPPLY VOLTAGE(V) SUPPLY VOLTAGE(V) Efficiency vs. Load Current VOUT=1V, L=2.2uH 100 EFFICIENCY (%) 90 Vin=3.3V 80 70 60 Vin=5V 50 40 30 20 10 0 10 100 1000 LOAD CURRENT(mA) MP28119 Rev.0.91 www.MonolithicPower.com 11/23/2011 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 5 MP28119 – ULTRA-SMALL 1.7MHZ, 600MA LOW-VOLTAGE SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS (continued) Vin=5V, Vout=1V, L1=2.2uH, C1=4.7uF, C2=10uF, TA=25oC, tested on MP28119EG-1.0, unless otherwise noted. Load Transient Light Load Operation Heavy Load Operation VIN=5V, IOUT=0mA->600mA Step VOUT=1V VIN=5V, VOUT=1V, IOUT=0A VIN=5V, VOUT=1V, IOUT=600mA VOUT 20mV/div VOUT 10mV/div VOUT 10mV/div VSW 5V/div VSW 5V/div 200ns/div 200ns/div Enable On Enable On Enable Off VIN=2.5V, VOUT=1V, IOUT=600mA VIN=5V, VOUT=1V, IOUT=600mA VIN = 2.5V, VOUT = 1V, IOUT = 0mA VOUT 1V/div VOUT 1V/div VOUT 1V/div VEN 5V/div VEN 5V/div VEN 5V/div VSW 5V/div VSW 5V/div VSW 5V/div 10 1ms/div 10 Enable Off Short Circuit Protection Short Circuit Recovery VIN = 5V, VOUT = 1V, IOUT = 0mA VIN=5V, IOUT=0mA VIN=5V, IOUT=0mA VOUT 1V/div VOUT 1V/div VOUT 1V/div VEN 5V/div VSW 5V/div VSW 5V/div VSW 5V/div 1ms/div MP28119 Rev.0.91 www.MonolithicPower.com 11/23/2011 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 6 MP28119 – ULTRA-SMALL 1.7MHZ, 600MA LOW-VOLTAGE SYNCHRONOUS STEP-DOWN CONVERTER OPERATION diode. The MP28119 can achieve 100% duty cycle. The duty cycle D of a step-down converter is defined as: The MP28119 is a constant frequency current mode PWM step-down converter. The MP28119 is optimized for low voltage, Li-Ion battery powered applications where high efficiency and small size are critical. The MP28119 uses an external resistor divider to set the output voltage from 0.6V to 6V. The device integrates both a main switch and synchronous rectifier, which provides high efficiency and eliminates an external Schottky D TON fOSC 100% VOUT 100% VIN Where TON is the main switch on time, fOSC is the oscillator frequency (1.7MHz), VOUT is the output voltage and VIN is the input voltage. PWM COMPARATOR Isense Output Discharge R Figure 1—Functional Block Diagram (MP28119EG) MP28119 Rev.0.91 www.MonolithicPower.com 11/23/2011 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 7 MP28119 – ULTRA-SMALL 1.7MHZ, 600MA LOW-VOLTAGE SYNCHRONOUS STEP-DOWN CONVERTER PWM COMPARATOR Isense 300k 450k Output Discharge R Figure 2—Functional Block Diagram (MP28119EG-1.0) MP28119 Rev.0.91 www.MonolithicPower.com 11/23/2011 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 8 MP28119 – ULTRA-SMALL 1.7MHZ, 600MA LOW-VOLTAGE SYNCHRONOUS STEP-DOWN CONVERTER 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 MP28119 switches at a constant frequency (1.7MHz) 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 either the next cycle starts. Dropout Operation The MP28119 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. Maximum Load current The MP28119 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. Output Discharge Function When the device is disabled, the part goes into output discharge mode automatically and its internal discharge MOSFET provides a resistive discharge path for the output capacitor. This function is only suitable for discharge output capacitor for the limited time. If the part is used in a pre-bias application, the external power supply providing the pre-bias should supply larger current than the discharge MOSFET sinks. Short Circuit Protection The MP28119 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. MP28119 Rev.0.91 www.MonolithicPower.com 11/23/2011 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 9 MP28119 – ULTRA-SMALL 1.7MHZ, 600MA LOW-VOLTAGE SYNCHRONOUS STEP-DOWN CONVERTER APPLICATION INFORMATION Output Voltage Setting (MP28119EG) The external resistor divider sets the output voltage (see Figure 3). The feedback resistor R1 also sets the feedback loop bandwidth with the internal compensation capacitor (see Figure 1). Choose R1 around 300kΩ for optimal transient response. R2 is then given by: R2 R1 VOUT 1 0. 6 V Table 1—Resistor Selection vs. Output Voltage Setting VOUT R1 R2 1.2V 300kΩ (1%) 300kΩ (1%) 1.5V 300kΩ (1%) 200kΩ (1%) 1.8V 300kΩ (1%) 150kΩ (1%) 2.5V 300kΩ (1%) 95.3kΩ (1%) For the fixed output versions (MP28119EG-1.0 and MP28119EG-1.2), R1 is shorted and R2 is open. Input Capacitor Selection The input capacitor reduces the surge current drawn from the input and switching noise from the device. The input capacitor impedance at the switching frequency shall be less than input source impedance to prevent high frequency switching current passing to the input. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. For most applications, a 4.7μF capacitor is sufficient. 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 <200mΩ. For most designs, the inductance value can be derived from the following equation: L VOUT VIN VOUT VIN IL fOSC Where ΔIL is the inductor ripple current. Choose inductor ripple current approximately 30% of the maximum load current, 600mA. The maximum inductor peak current is: IL(MAX ) ILOAD IL 2 Under light load conditions below 100mA, larger inductance is recommended for improved efficiency. Output Capacitor Selection The output capacitor keeps output voltage ripple small and ensures regulation loop stable. The output capacitor impedance shall be low at the switching frequency. Ceramic capacitors with X5R or X7R dielectrics are recommended. The output ripple ΔVOUT is approximately: VOUT VOUT VIN VOUT 1 ESR VIN fOSC L 8 fOSC C3 PCB Layout Guide PCB layout is very important to achieve stable operation. It is highly recommended to duplicate EVB layout for optimum performance. If change is necessary, please follow these guidelines and take Figure 3 for reference. 1) Keep the path of switching current short and minimize the loop area formed by Input cap, high-side MOSFET and low-side MOSFET. 2) Bypass ceramic capacitors are suggested to be put close to the Vin Pin. 3) Place the external feedback resistors as close to the FB pin as possible. 4) Route SW away from sensitive analog areas such as FB. 5) Connect IN, SW, and especially GND respectively to a large copper area to cool the chip to improve thermal performance and longterm reliability. MP28119 Rev.0.91 www.MonolithicPower.com 11/23/2011 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 10 MP28119 – ULTRA-SMALL 1.7MHZ, 600MA LOW-VOLTAGE SYNCHRONOUS STEP-DOWN CONVERTER INPUT 2.5V - 6V 7 IN C1 SW 1 L1 OUTPUT R1 MP28119 4 EN FB 5 GND R2 6,8 C2 MP28119 Typical Application Circuit TOP Layer Bottom Layer Figure 3—MP28119 Typical Application Circuit and PCB Layout Guide MP28119 Rev.0.91 www.MonolithicPower.com 11/23/2011 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 11 MP28119 – ULTRA-SMALL 1.7MHZ, 600MA LOW-VOLTAGE SYNCHRONOUS STEP-DOWN CONVERTER PACKAGE INFORMATION 2MM X 2MM QFN8 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. MP28119 Rev. 0.91 www.MonolithicPower.com 11/23/2011 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 12