MP2127 2.7-6V Input, 2A, 1.2MHz Synchronous Step-Down Converter The Future of Analog IC Technology DESCRIPTION FEATURES The MP2127 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 MP2127 can provide up to 2A 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 MP2127 is stable with ceramic capacitors and small inductors. Fault condition protection includes cycle-by-cycle current limiting and thermal shutdown. • • • MP2127 is available in 3mmx3mm QFN package. the small 6-pin • • • • • • • • Output Adjustable from 0.8V to VIN Up to 95% Efficiency 100% Duty Cycle for Low Dropout Applications Power Good Indicator Output 1.2MHz Fixed Switching Frequency Stable with Low ESR Output Ceramic Capacitors Thermal Shutdown Cycle-by-Cycle Over Current Protection Short circuit protection 2.7V-6V Input Operation Range Available in 6-pin 3x3mm QFN APPLICATIONS • • • • Smart Phones, PDA’s DVD+/-RW Drives Digital Cameras Portable Instruments “MPS” and “The Future of Analog IC Technology” are Trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION R3 100k 6V 4 5 C1 10 2 PVIN VIN GND PGOOD MP2127 SW VOUT 1.2V/2A L1 3.3 FB 1 90 PGOOD 6 3 100 R1 20k R2 40k C1 33 EFFICIENCY (%) VIN 2.7V Efficiency vs. Load Current VIN=3V 80 70 VIN=5V 60 50 40 30 20 10 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 LOAD CURRENT(A) MP2127 Rev. 0.91 4/27/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 1 MP2127 – 2.7-6V, 2A, 1.2MHZ SYNCHRONOUS STEP-DOWN CONVERTER ORDERING INFORMATION Part Number* MP2127DQ Package QFN6 (3mm x 3mm) Top Marking Free Air Temperature (TA) 8G –40°C to +85°C * For Tape & Reel, add suffix –Z (e.g. MP2127DQ–Z). For RoHS compliant packaging, add suffix –LF (e.g. MP2127DQ–LF–Z) PACKAGE REFERENCE TOP VIEW FB 1 6 PGOOD GND 2 5 VIN SW 3 4 PVIN ABSOLUTE MAXIMUM RATINGS (1) Recommended Operating Conditions PVIN, VIN to GND......................–0.3V to + 7.0V SW to GND .......................... –0.3V to VIN + 0.3V PGOOD, FB to GND ...................–0.3V to +6.5V Operating Temperature............. –40°C to +85°C Continuous Power Dissipation…(TA = +25°C) (2) ………………………………………………....2.5W Junction Temperature ...............................150°C Lead Temperature ....................................260°C Storage Temperature ............. –65°C to +150°C Supply Voltage VIN .............................2.7V to 6V Operating Junct. Temp (TJ)...... -40°C to +125°C MP2127 Rev. 0.91 4/27/2010 Thermal Resistance (4) θJA (3) θJC QFN6 (3mm x 3mm) ...............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. © 2010 MPS. All Rights Reserved. 2 MP2127 – 2.7-6V, 2A, 1.2MHZ SYNCHRONOUS STEP-DOWN CONVERTER ELECTRICAL CHARACTERISTICS (5) VIN = 3.6V, TA = +25°C, unless otherwise noted. Parameters Supply Current Thermal Shutdown Trip Threshold IN Undervoltage Lockout Threshold IN Undervoltage Lockout Hysteresis Regulated FB Voltage FB Input Bias Current SW PFET On Resistance SW NFET On Resistance SW PFET Peak Current Limit Switching Frequency OVP threshold (PGOOD Output High) OVP threshold (Fault Detected) OVP Hysteresis Symbol Condition IIN TSD INUVVTH Typ Max Units VFB = 0.9V 500 750 μA Hysteresis = 20°C 150 Rising Edge 2.15 INUVHYS VFB IFB HSRDS-ON LSRDS-ON ILIMIT VFB OVPVFB OVP+ 2.40 °C 2.65 160 TA = +25°C -40°C≤ TA≤ +85°C VFB = 0.9V ISW = 100mA ISW = -100mA Duty Cycle=100% Duty Cycle=50% (6) 0.784 0.776 -50 0.19 0.16 2.2 2.5 1.0 FSW VFB ramps up from nominal operating point VFB ramps up from nominal operating point VFB 0.800 0.800 -2 0.23 0.2 3.0 3.5 1.2 0.816 0.824 +50 0.27 0.24 3.8 4.5 1.4 103% VFB OVP+ PGOOD, Output Low VFB OVP- 4.5V≤VIN≤5.5V, IOUT=100mA 0A ≤IOUT≤ 2A V nA Ω Ω A MHz VFB VFB Ramp up VFB, starting at VFB≤700mV Ramp down VFB,starting at VFB= VFB nom ISINK = 6mA V mV 111% 25 PGOOD, Output High PGOOD output low voltage PGOOD Deglitch Time Line Regulation Load Regulation Min 94% 160 0.1 0.1 VFB mV 98.5% VFB 95% VFB 0.4 V μs % % Notes: 5) Production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization. 6) Guaranteed by design MP2127 Rev. 0.91 4/27/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 3 MP2127 – 2.7-6V, 2A, 1.2MHZ SYNCHRONOUS STEP-DOWN CONVERTER PIN FUNCTIONS Pin # Name 1 FB 2 GND 3 4 5 SW PVIN VIN 6 PGOOD MP2127 Rev. 0.91 4/27/2010 Description Feedback input. An external resistor divider from the output to GND, tapped to the FB pin sets the output voltage. Ground pin. This pin is the reference ground of the regulated output voltage. For this reason care must be taken in PCB layout. Suggested to be connected to GND with copper and vias. Connect exposed pad to ground plane for proper thermal performance. Switch node to the inductor Input supply pin for power FET Input Supply pin for controller Power-good indicator output. “Low” output indicates output is outside the window of regulation level. PGOOD is pulled down in shutdown. PGOOD output has 160us deglitch timer to avoid false trigger during transient response. www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 4 MP2127 – 2.7-6V, 2A, 1.2MHZ SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS VIN = 5V, VOUT = 1.2V, TA = +25ºC, unless otherwise noted. VIN=3V 660 640 VIN=5V 620 60 IIN (uA) 50 40 600 580 560 30 20 540 10 520 500 0 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2 4 0.20 VIN=5V 0.12 0.08 0.04 VIN=3V -0.04 -0.08 -0.12 -0.16 -0.20 0 0.5 1 1.5 LOAD CURRENT(A) MP2127 Rev. 0.91 4/27/2010 35 30 25 20 15 10 5 0 0 8 2 0.5 1 1.5 2 OUTPUT CURRENT (A) Line Regulation NORMALIZED OUTPUT VOLTAGE (%) NORMALIZED OUTPUT VOLTAGE (%) Load Regulation 0.00 40 V IN(V) LOAD CURRENT(A) 0.16 6 Ipeak vs. Duty 4.2 0.20 IO=0A 0.15 3.9 0.10 0.05 IPEAK (A) EFFICIENCY (%) 80 70 CASE TEMPERATURE RISE (OC) 680 100 90 Case Tem perature Rise vs. Output Current Enabled Supply Current vs. Input Voltage Efficiency vs. Load Current IO=1A 0.00 -0.05 -0.10 3.6 3.3 IO=2A -0.15 3 -0.20 2 3 4 5 6 INPUT VOLTAGE (V) 7 0% 20% 40% 60% 80% 100% DUTY CYCLE www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 5 MP2127 – 2.7-6V, 2A, 1.2MHZ SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = 5V, VOUT = 1.2V, TA = +25ºC, unless otherwise noted. Short Entry Short Recovery Full Load Full Load VOUT 1V/div VOUT 500mV/div VOUT 500mV/div SW 2V/div SW 5V/div SW 2V/div VIN 5V/div IINDUCTOR 2A/div VIN 5V/div IINDUCTOR 2A/div IINDUCTOR 2A/div SW 5V/div VIN 5V/div IINDUCTOR 2A/div Power Good Power Good Power Up with 2A Load VOUT 500mV/div Power Up without Load VOUT 1V/div VOUT 1V/div SW 5V/div SW 5V/div PGood 5V/div PGood 5V/div IINDUCTOR 500mA/div IINDUCTOR 500mA/div Input Ripple Voltage Output Ripple Voltage Load Transient Response Full Load IOUT=2A IOUT=1A-2A VOUT 20mV/div VIN 50mV/div VOUT 50mV/div SW 2V/div VIN 5V/div SW 2V/div 400ns/div MP2127 Rev. 0.91 4/27/2010 IINDUCTOR 2A/div 400ns/div IOUT 1A/div www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 6 MP2127 – 2.7-6V, 2A, 1.2MHZ SYNCHRONOUS STEP-DOWN CONVERTER FUNCTIONAL BLOCK DIAGRAM PVIN VIN Bias & Voltage Reference 0.8V ICS Slope Comp + RI IAMP 10X Current Sense Amp 0.74V Feedback Error Amp EAO EAMP FB To controller blocks 0.86V - 0.04 - Main Switch (PCH) + + + PWMCMP PWM PWM 240k RZ CC 1.1M 17pF SW Control 1.2MHz Oscillator OSC Logic Synchronou s Rectifier (NCH) GND 0.86V + COMP PGOOD + COMP 0.74V MP2127 Rev. 0.91 4/27/2010 - www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 7 MP2127 – 2.7-6V, 2A, 1.2MHZ SYNCHRONOUS STEP-DOWN CONVERTER OPERATION The MP2127 is a fixed frequency 1.2MHz current mode 2A step-down converter, optimized for low voltage, Li-Ion battery powered applications where high efficiency and small size are critical. MP2127 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. 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 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 MP2127 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. MP2127 Rev. 0.91 4/27/2010 Dropout Operation The MP2127 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 MP2127 can operate down to 2.7V 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 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 approaches 0.8V. PGOOD Indicator MP2127 provides an open-drain PGOOD output that becomes high-impedance (open circuit) after output level reaches regulation after startup. PGOOD is pulled low if the output goes out of regulation level for more than the de-glitch time of 160us, or when device enters shutdown. www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 8 MP2127 – 2.7-6V, 2A, 1.2MHZ SYNCHRONOUS STEP-DOWN CONVERTER APPLICATION INFORMATION Output Voltage Setting The output voltage is set by the external resistor divider: VOUT = 0.8 ⋅ (1 + R1 ) R2 1 R1 + 240k ⋅ (1 + R1 ) R2 To minimize the impact of R1 to loop bandwidth, one should choose R1 much smaller than 240k. Some recommended value for common output voltage is listed below: Table 1—Resistor Selection vs. Output Voltage Setting VOUT R1 1.2V 1.8V 2.5V R2 20kΩ (1%) 40.2kΩ (1%) 49.9kΩ (1%) 40.2kΩ (1%) 84.5kΩ (1%) 40.2kΩ (1%) 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. See Table 2 for recommended inductors and manufacturers. For most designs, the inductance value can be derived from the following equation: L= VOUT × (VIN − VOUT ) VIN × ΔIL × fOSC Where ΔIL is inductor ripple current. Choose inductor ripple current approximately 30% of the maximum load current, 2A. The maximum inductor peak current is: IL(MAX ) = ILOAD + MP2127 Rev. 0.91 4/27/2010 Manufacturer Part Number TOKO The divider ratio also affects the loop bandwidth of the step-down converter. The approximate relationship between them is given below: BW ∝ Table 2—Suggested Inductors TDK B1015AS3R0N RLF7030T3R3M4R1 Inductance (μH) Dimensions LxWxH (mm3) 3 8.4X8.3X4 3.3 7.3X6.8X3.2 Input Capacitor CIN 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 10μF capacitor is sufficient. Output Capacitor COUT 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. For forced PWM mode operation, the output ripple ΔVOUT is approximately: V ⋅ (V IN − VOUT ) 1 1 ΔVOUT = OUT ( R ESR + ⋅ )F V IN ⋅ f OSC ⋅ L 8 f OSC ⋅ C OUT or most applications, a 33μF capacitor is sufficient. Thermal Dissipation Power dissipation shall be considered when operates MP2127 at maximum 2A output current. If the junction temperature rises above 150°C, MP2127 will be shut down by internal thermal protection circuitry. ΔIL 2 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 9 MP2127 – 2.7-6V, 2A, 1.2MHZ SYNCHRONOUS STEP-DOWN CONVERTER The junction-to-ambient thermal resistance of the 6-pin QFN (3mm x 3mm) RΘJA is 50°C/W. The maximum allowable power dissipation is about1.6W when MP2127 is operating in a 70°C ambient temperature environment: 150 o C − 70 o C PD MAX = 50 o C / W = 1 .6 W GND PC Board Layout The high current paths (GND, IN and SW) should be placed very close to the device with short, direct and wide traces. Input capacitors should be placed as close as possible to the respective IN and GND pins. The external feedback resistors shall be placed next to the FB pins. Keep the switching nodes SW short and away from the feedback network. GND C2 L1 PVIN 4 3 SW VIN 5 2 GND PGOOD 6 1 FB R3 R2 C1 R1 R4 C3 C4 VIN GND VOUT Bottom Layer Top Layer MP2127 Rev. 0.91 4/27/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 10 MP2127 – 2.7-6V, 2A, 1.2MHZ SYNCHRONOUS STEP-DOWN CONVERTER PACKAGE INFORMATION QFN6 (3mmx3mm) 2.90 3.10 0.35 0.55 PIN 1 ID MARKING 0.35 0.45 1.40 1.60 PIN 1 ID SEE DETAIL A 1 6 2.90 3.10 PIN 1 ID INDEX AREA 2.20 2.40 0.95 BSC 3 4 TOP VIEW BOTTOM VIEW PIN 1 ID OPTION A R0.20 TYP. PIN 1 ID OPTION B R0.20 TYP. 0.80 1.00 0.20 REF 0.00 0.05 SIDE VIEW DETAIL A NOTE: 2.90 0.80 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) JEDEC REFERENCE IS MO-229, VARIATION VEEA-2. 5) DRAWING IS NOT TO SCALE. 1.50 0.40 2.30 0.95 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. MP2127 Rev. 0.91 4/27/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 11