MP2136 2.5V to 6V Input, 2MHz, 1A Synchronous Step-Down Converter The Future of Analog IC Technology DESCRIPTION FEATURES The MP2136 is a 2MHz 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 MP2136 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. 2MHz 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 6-pin, QFN6 2mm×2mm package APPLICATIONS The MP2136 is available in a 6-pin, QFN6 2mm×2mm package. • • • • • • 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 Efficiency vs. Output Current VIN 2.5V - 6V OFF ON EN C1 4.7uF 3 IN 4 SW MP2136EG 2 EN FB 1 NC GND L1 1.2uH 100 R1 300k 1% 6 5 R2 300k 1% C2 10uF VOUT 1.2V/1A L=2.2uH Vo=1.2V Vin=3.3V 90 80 EFFICIENCY (%) U1 70 60 Vin=6V Vin=5V Vin=2.5V 50 40 30 20 10 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 OUTPUT CURRENT (A) MP2136 Rev. 0.9 8/23/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 1 MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER ORDERING INFORMATION Part Number* Package Top Marking Free Air Temperature(TA) MP2136EG QFN6 (2mmx2mm) 6Q –20°C to +85°C * For Tape & Reel, add suffix –Z (eg. MP2136EG–Z). For RoHS Compliant Packaging, add suffix –LF (eg. MP2136EG–LF–Z) PACKAGE REFERENCE TOP VIEW NC 1 6 FB EN 2 5 GND VIN 3 4 SW ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance 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 (2) Continuous Power Dissipation. (TA = +25°C) QFN6 (2mmx2mm) .................................... 2.5W Junction Temperature ...............................150°C Lead Temperature ....................................260°C Storage Temperature............... –65°C to +150°C QFN6 (2mmx2mm) ................. 50 ...... 12... °C/W Recommended Operating Conditions (3) Supply Voltage VIN .............................2.5V to 6V Output Voltage VOUT ...........................0.6V to 6V Operating Junct.Temp. (TJ)...... –20°C to +125°C MP2136 Rev. 0.9 8/23/2010 (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. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 2 MP2136 – 2.5V TO 6V INPUT, 2MHz, 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 0.4 150 2 150 20 Units V V µs MHz °C °C Note: 5) Production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization. MP2136 Rev. 0.9 8/23/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 3 MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS VOUT=1.2V, L=1.2uH, C2=10uF, TA=25°C, unless otherwise noted. Steady State Operation Steady State Operation Steady State Operation Vin=2.5V, Vo=1.2V, Io=0A Vin=2.5V, Vo=1.2V, Io=1A Vin=6V, Vo=1.2V, Io=0A VOUT/AC 10mV/div. VOUT/AC 10mV/div. VOUT/AC 10mV/div. VSW 2V/div. VSW 2V/div. IINDUCTOR 500mA/div. VSW 5V/div. IINDUCTOR 500mA/div. IINDUCTOR 500mA/div. 200ns/div. 200ns/div. 200ns/div. Steady State Operation Start-up Through Enable Start-up Through Enable Vin=6V, Vo=1.2V, Io=1A Vin=2.5V, Vo=1.2V, Io=0A Vin=2.5V, Vo=1.2V, Io=1A VOUT/AC 10mV/div. VSW 5V/div. IINDUCTOR 500mA/div. VEN 2V/div. VEN 2V/div. VOUT 500mV/div. VOUT 500mV/div. VSW 2V/div. VSW 2V/div. IINDUCTOR 500mA/div. IINDUCTOR 1A/div. 40us/div. 200ns/div. 40us/div. Start-Up Through EN Start-Up Through EN Power-Down Through EN Vin=6V, Vo=1.2V, Io=0A Vin=6V, Vo=1.2V, Io=1A Vin=2.5V, Vo=1.2V, Io=0A VEN 2V/div. VEN 2V/div. VEN 2V/div. VOUT 500mV/div. VOUT 500mV/div. VOUT 500mV/div. VSW 5V/div. VSW 5V/div. VSW 2V/div. IINDUCTOR 1A/div. IINDUCTOR 500mA/div. IINDUCTOR 500mA/div. 40us/div. MP2136 Rev. 0.9 8/23/2010 40us/div. www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 2s/div. 4 MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VOUT=1.2V, L=1.2uH, C2=10uF, TA=25°C, unless otherwise noted. 2.1 1.210 2.05 1.208 1.2 1.206 2 1.202 1.9 1.200 1.85 1.198 Vin=3.3V Vin=5V 1.196 1.8 1.190 Falling 0.6 0.2 1.192 1.7 -40 -25 -10 5 20 35 50 65 80 95 110125 0.8 0.4 1.194 1.75 Rising 1 1.204 1.95 MP2136 Rev. 0.9 8/23/2010 1.4 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 2.5 3 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 3.5 4 4.5 5 5.5 6 5 MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER PIN FUNCTIONS Pin # 1 Name NC 2 EN 3 IN 4 SW 5 6 Description No connection. Leave Pin1 disconnection. Regulator Enable Control Input. Drive EN above 1.6V to turn on the part. Drive EN below 0.4V to turn it off. Supply Input. Bypass to GND with a 4.7µF or bigger value ceramic capacitor. Power Switch Output. Inductor connection to drains of the internal PFET and NFET switches. GND, Exposed Ground. Connect exposed pad to ground plane for optimal thermal performance. Pad Feedback Input. Connect FB to the center point of the external resistor divider. The FB regulated feedback voltage is 0.6V. MP2136 Rev. 0.9 8/23/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 6 MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER FUNCTIONAL BLOCK DIAGRAM IN EN BIAS &VOLTAGE 0.6V REFERENCE 2MHz OSCILLATOR Slope Comp OSC ISW Slope Comp 150us INTERNAL SS FB EAO PWM ISW DH PWM CONTROL LOGIC PGATE DL MAIN SWITCH PCH HIGH SIDE GATE DRIVE 0.6V SW 1.2MEG 17pF 0.5pF DL LOW SIDE GATE DRIVE SYNCHRONOUS RECTIFIER NCH GND Figure 1— Functional Block Diagram MP2136 Rev. 0.9 8/23/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 7 MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER FUNCTIONAL DESCRIPTION MP2136 is a 2MHz 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 MP2136 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 (2MHz) 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 MP2136 switches at a constant frequency (2MHz) 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. Dropout Operation The MP2136 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. Short Circuit Protection The MP2136 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 MP2136 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. When the main switch is off, the synchronous rectifier will be turned on immediately and stay on until the next cycle starts. MP2136 Rev. 0.9 8/23/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 8 MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER APPLICATION INFORMATION Output Voltage Setting The external resistor divider sets the output voltage. The feedback resistor R1 also sets the feedback loop bandwidth with the internal compensation capacitor. 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%) Inductor Selection A 0.68µH 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 ∆IL is the inductor ripple current. Choose inductor ripple current approximately 30% of the maximum load current, 1A. The maximum inductor peak current is: IL(MAX ) = ILOAD + ∆IL 2 Under light load conditions below 100mA, larger inductance is recommended for improved efficiency. MP2136 Rev. 0.9 8/23/2010 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. The input capacitor absorbs the input switching current, so it requires an adequate ripple current rating. The RMS current through the input capacitor can be estimated by: ICIN = ILOAD × VOUT V × (1 − OUT ) VIN VIN The worse case condition occurs at VIN=2VOUT， where: ICIN = ILOAD 2 For simplification, choose the input capacitor whose RMS current rating greater than half of the maximum load current. For most applications, a 4.7µF capacitor is sufficient. 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 ∆VOUT is approximately: ∆VOUT ≤ ⎞ VOUT × (VIN − VOUT ) ⎛ 1 ⎟ × ⎜⎜ ESR + VIN × fOSC × L 8 × fOSC × C3 ⎟⎠ ⎝ For most applications, a 10uF capacitor is sufficient. www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 9 MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER PCB LAYOUT GUIDE PCB layout is very important to achieve stable operation. It is highly recommended to duplicate EVB layout for optimum performance. 2) If change is necessary, please follow these guidelines and take Figure 2 for reference. 4) Route SW away from sensitive analog areas such as FB. 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. 5) Connect IN, SW, and especially GND respectively to a large copper area to cool the chip to improve thermal performance and long-term reliability. Top Layer Ensure all feedback connections are short and direct. Place the feedback resistors as close to the chip as possible. Bottom Layer Figure 2—MP2136 Suggested Layout MP2136 Rev. 0.9 8/23/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 10 MP2136 – 2.5V TO 6V INPUT, 2MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER PACKAGE INFORMATION QFN6 (2mmX2mm) 1.90 2.10 0.30 0.40 PIN 1 ID MARKING 0.20 0.30 1.90 2.10 PIN 1 ID INDEX AREA 0.65 0.85 PIN 1 ID SEE DETAIL A 1 6 1.25 1.45 0.65 BSC 3 4 TOP VIEW BOTTOM VIEW 0.80 1.00 0.20 REF PIN 1 ID OPTION A 0.30x45º TYP. PIN 1 ID OPTION B R0.20 TYP. 0.00 0.05 SIDE VIEW DETAIL A 1.90 0.70 0.70 0.25 1.40 0.65 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. MP2136 Rev. 0.9 8/23/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 11