MP2125 Dual 1.5A, 1.2MHz Synchronous Step-Down Converter The Future of Analog IC Technology DESCRIPTION FEATURES The MP2125 is a fully integrated dual PWM step-down converter with built-in internal power MOSFETs. It is ideal for powering portable equipment that runs from a single cell LithiumIon (Li+) Battery, with an input range from 2.7V to 6V. The MP2125 can provide up to 1.5A of load current with output voltage as low as 0.8V for each output. It can also operate at 100% duty cycle for low dropout applications. • • • • • With peak current mode control and internal compensation, the MP2125 is stable with ceramic capacitors and small inductors. • • • • • • Fault condition protection includes cycle-bycycle current limiting and thermal shutdown. MP2125 is available in 3mmx4mm QFN package. the small 2.7V-6V Input Operation Range Each Output Adjustable from 0.8V to VIN 1uA Shutdown Current Up to 92% Efficiency 100% Duty Cycle for Low Dropout Applications Fixed 1.2MHz Frequency Stable with Low ESR Output Ceramic Capacitors Cycle-by-Cycle Over Current Protection Thermal Shutdown Short Circuit Protection Available in 14-pin 3mmx4mm QFN package APPLICATIONS 14-pin • • • • • • Solid State Disk DVD+/-RW Drivers Smart Phones PDAs Digital Cameras Portable Instruments “MPS” and “The Future of Analog IC Technology” are Registered Trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION Efficiency Curve C1 12 PVIN1 EN1 13 VIN1 2 3 SW1 1 GND1 Vin2 2.7V-6V 4 N/C 5 6 C2 MP2125 FB1 N/C PVIN2 EN2 VIN2 SW2 9 GND2 11 8 FB2 R1 Rt R2 C3 EN2 Vout2 1.8V/1.5A L2 R3 Rt 90 Vout1 1.8V/1.5A L1 7 10 100 EN1 14 R4 C4 80 EFFICIENCY (%) Vin1 2.7V-6V 70 Vin=6V Vin=3V Vin=5V 60 50 40 30 20 10 0 0 0.3 0.6 0.9 1.2 1.5 OUTPUT CURRENT (A) MP2125 Rev. 1.0 12/24/2013 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 1 MP2125 – DUAL 1.5A, 1.2MHZ SYNCHRONOURS STEP-DOWN CONVERTER ORDERING INFORMATION Part Number* MP2125DL Package QFN14 (3mm x 4mm) Top Marking 2125 Free Air Temperature (TA) –40°C to +85°C For Tape & Reel, add suffix –Z (e.g. MP2125DL–Z). For RoHS compliant packaging, add suffix –LF (e.g. MP2125DL–LF–Z) PACKAGE REFERENCE TOP VIEW FB1 1 14 EN1 GND1 2 13 VIN1 SW1 3 12 PVIN1 N/C 4 11 N/C PVIN2 5 10 SW2 VIN2 6 9 GND2 EN2 7 8 FB2 MP2125 ABSOLUTE MAXIMUM RATINGS (1) PIN, 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 MP2125 Rev. 1.0 12/24/2013 Recommended Operating Conditions (3) Supply Voltage VIN .............................2.7V to 6V Operating Junct. Temp (TJ)..... -40°C to +125°C Thermal Resistance (4) θJA θJC QFN14(3mm X 4mm)..............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. © 2013 MPS. All Rights Reserved. 2 MP2125 – DUAL 1.5A, 1.2MHZ SYNCHRONOUS STEP-DOWN CONVERTER ELECTRICAL CHARACTERISTICS (5) VIN = VEN = 3.6V, TA = +25°C, unless otherwise noted. Parameters Condition Supply Current Shutdown Current Thermal Shutdown Trip Threshold EN Trip Threshold EN Input Current EN Input Current IN Undervoltage Lockout Threshold IN Undervoltage Lockout Hysteresis 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 Typ Max Units VEN= VIN, VFB = 0.9V 600 750 μA VEN= 0V, VIN = 6V Hysteresis = 20°C -40°C ≤ TA ≤ +85°C VEN = 0V VEN = 6V Rising Edge 0.01 150 1.0 0.1 6 2.40 160 0.800 0.800 -2 0.25 0.2 1 μA °C V μA μA V mV V V nA Ω Ω 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% Min 0.3 2.15 0.784 0.776 -50 1.5 1.0 2.65 0.816 0.824 +50 -1 0.1 1 μA -5 1.5 5 μA 1.0 3.0 1.2 1.4 A MHz Notes: 5) Production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization PIN FUNCTIONS Pin # Name Description 1 2 3 4 5 6 FB1 GND1 SW1 N/C PVIN2 VIN2 7 EN2 8 9 10 11 12 13 FB2 GND2 SW2 N/C PVIN1 VIN1 14 EN1 Feedback input voltage for channel 1 Ground pin 1 Switch node to the inductor for channel 1 Not connect Channel 2 input supply pin for power FET Channel 2 input supply pin for controller Enable input for channel 2, “High” enables channel 2. EN2 is pulled to GND with 1Meg internal resistor Feedback input voltage for channel 2 Ground pin 2 Switch node to the inductor for channel 2 Not connect Channel 1 input supply pin for power FET Channel 1 input supply pin for controller Enable input for channel 1, “High” enables channel 1. EN1 is pulled to GND with 1Meg internal resistor MP2125 Rev. 1.0 12/24/2013 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 3 MP2125 – DUAL 1.5A, 1.2MHZ SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS VIN = 5V, VOUT = 1.8V, L=3.3uH, TA = +25ºC, one channel, unless otherwise noted. Efficiency Curve EenableSupply Current vs. Input Voltage Case Tem perature Risevs. Output Current VEN=3V 100 35 700 30 650 25 600 20 40 550 15 30 500 10 450 5 90 EFFICIENCY (%) 80 70 V IN=6V V IN=3V V IN=5V 60 50 20 10 0 0 0.3 0.6 0.9 1.2 400 2.5 1.5 3 OUTPUT CURRENT (A) 3.5 4 4.5 5 5.5 0 0.2 0.4 0.6 0.8 6 Load Regulation Load Regulation VIN=3V VIN=5V VIN=6V 0.20 0.15 0.15 0.15 0.00 -0.05 -0.10 -0.15 -0.20 0 0.3 0.6 0.9 1.2 0.10 0.05 0.00 -0.05 -0.10 -0.15 -0.20 1.5 LOAD REGULATION (%) 0.20 0.05 0 OUTPUT CURRENT (A) 0.3 0.6 0.9 1.2 1.5 OUTPUT CURRENT (A) Line Regulation 1.2 1.4 1.6 Load Regulation 0.20 0.10 1 OUTPUT CURRENT (A) INPUT VOLTAGE(V) LOAD REGULATION (%) LOAD REGULATION (%) IOUT1=IOUT2 750 0.10 0.05 0.00 -0.05 -0.10 -0.15 -0.20 0 0.3 0.6 0.9 1.2 1.5 OUTPUT CURRENT (A) Peak Current vs. Duty Cycle 4.5 0.08 0.04 PEAK CURRENT(A) LINE REGULATION (%) 0.06 IOUT=0A 0.02 0.00 -0.02 IOUT=0.75A -0.04 -0.06 IOUT=1.5A -0.08 4 3.5 3 2.5 -0.10 -0.12 2.5 2 3 3.5 4 4.5 5 5.5 INPUT VOLTAGE (V) MP2125 Rev. 1.0 12/24/2013 6 40 50 60 70 80 90 100 DUTY CYCLE (%) www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 4 MP2125 – DUAL 1.5A, 1.2MHZ SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = 5V, VOUT = 1.8V, L=3.3uH, TA = +25ºC, one channel, unless otherwise noted. Short Entry VOUT 1V/div SW 5V/div VIN 5V/div IINDUCTOR 2A/div Short Recovery Power Up without Load VOUT 1V/div VOUT 1V/div SW 5V/div SW 5V/div VIN 5V/div VIN 5V/div IINDUCTOR 2A/div IINDUCTOR 2A/div VOUT 1V/div VOUT 1V/div VOUT 1V/div SW 5V/div SW 5V/div SW 5V/div VIN 5V/div IINDUCTOR 2A/div VIN 20mV/div EN 5V/div IINDUCTOR 2A/div VOUT 10mV/div EN 5V/div IINDUCTOR 2A/div VOUT 50mV/div SW 2V/div SW 2V/div MP2125 Rev. 1.0 12/24/2013 IINDUCTOR 2A/div IOUT 500mA/div www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 5 MP2125 – DUAL 1.5A, 1.2MHZ SYNCHRONOUS STEP-DOWN CONVERTER FUNCTIONAL BLOCK DIAGRAM PVIN1 VIN1 To controller blocks Bias EN1 0.8V ICS Feedback Error Amp Slope Comp + EAO EAMP FB1 IAMP 10X Current Sense Amp Voltage Reference - 0.04 - Main Switch (PCH) + + + PWMCMP PWM - PWM Control RZ CC 1.2M 17pF Logic 1.2MHz Oscillator OSC SW1 Synchronous Rectifier (NCH) Figure 1 -Functional Block Diagram (1/2 of the MP2125) MP2125 Rev. 1.0 12/24/2013 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 6 MP2125 – DUAL 1.5A, 1.2MHZ SYNCHRONOUS STEP-DOWN CONVERTER OPERATION The MP2125 is a dual channel, fixed frequency, current mode step-down converter, optimized for low voltage, Li-Ion battery powered applications where high efficiency and small size are critical. MP2125 integrates two high side PFET main switches and two low side synchronous rectifiers. It always operates in continuous conduction mode, simplifies the control scheme and eliminates the random spectrum noise due to discontinuous conduction mode. turned on to provide the inductor current. The synchronous rectifier will stay on until the next oscillator cycle. The steady state duty cycle D for this mode can be calculated as: 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. 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 switches and synchronous rectifiers. The MP2125 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 for each channel, 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 MP2125 Rev. 1.0 12/24/2013 Dropout Operation The MP2125 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 Maximum Load Current The MP2125 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. www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 7 MP2125 – DUAL 1.5A, 1.2MHZ SYNCHRONOUS STEP-DOWN CONVERTER APPLICATION INFORMATION The MP2125 has two channels: channel 1 and channel 2. The following formulates are used for components selection of both channels. 8 . 0 ⎞ ⎟ ⎠ 2 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 VOUT/ V Rt/ kΩ R1/ kΩ R2/ kΩ L1/ μH C2/ μF 1.2 1.8V 2.5V 3.3V 300 243 100 100 4.99 4.99 121 121 10 4.02 57.6 39 2.2 3.3 3.3 3.3 22 22 22 22 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: 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. MP2125 Rev. 1.0 12/24/2013 ΔIL 2 Table 2—Suggested Inductors Manufacturer Toko Rt is recommended when output voltage is high, as the Figure 2 shows. L= IL(MAX ) = ILOAD + 1 ⎛ ×⎜ + ⎝ T U VO = R R 1 Output Voltage Setting The external resistor divider sets the output voltage. The maximum inductor peak current is: Cooper TDK Part Number Inductance (μH) Dimensions LxWxH (mm3) 3.3 6.3X6.2X3.5 3.3 5.2X5.2X2.5 3.3 7X7X4.5 D63CB#A916 CY-3R3M SD25-3R3 SLF7045T3R3M2R5-PF Input Capacitor CIN Selection The input capacitor reduces the surge current drawn from the input and switching noise from the device. 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: ΔVOUT = VOUT ⋅ (VIN − VOUT ) 1 1 (RESR + ⋅ ) VIN ⋅ fOSC ⋅ L 8 fOSC ⋅ COUT For most applications, a 22μF capacitor is sufficient. Thermal Dissipation Power dissipation shall be considered when operates MP2125 at maximum 1.5A output current. If the junction temperature rises above 150°C, MP2125 will be shut down by internal thermal protection circuitry. The junction-to-ambient thermal resistance of the 14-pin QFN (3mm x 4mm) RΘJA is 50°C/W. The maximum allowable power dissipation is about 1.6W when MP2125 is operating in a 70°C ambient temperature environment: PD MAX = 150 o C − 70 o C 50 o C / W www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. = 1 .6 W 8 MP2125 – DUAL 1.5A, 1.2MHZ SYNCHRONOURS STEP-DOWN CONVERTER PCB Layout PCB layout is very important to achieve stable operation. Please follow these guidelines and take Figure3 for references. 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. VOUT1 R1 C3 VIN1 R2 L1 1 14 EN1 GND1 2 R6 C2 13 VIN1 SW1 3 N/C 4 PVIN2 5 10 SW2 VIN2 6 9 GND2 EN2 7 8 FB2 12 PVIN1 2 11 N/C R4 VIN2 C1 R5 FB1 GND GND L2 C4 R3 VOUT2 Top Layer Bottom Layer Figure 3 -PCB Layout MP2125 Rev. 1.0 12/24/2013 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 9 MP2125 – DUAL 1.5A, 1.2MHZ SYNCHRONOURS STEP-DOWN CONVERTER PACKAGE INFORMATION QFN14 (3mm x 4mm) 2.90 3.10 1.60 1.80 0.30 0.50 PIN 1 ID SEE DETAIL A PIN 1 ID MARKING 1 14 0.18 0.30 3.20 3.40 3.90 4.10 PIN 1 ID INDEX AREA 0.50 BSC 7 8 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 2.90 0.70 NOTE: 1.70 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 VGED-3. 5) DRAWING IS NOT TO SCALE. 0.25 3.30 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. MP2125 Rev. 1.0 12/24/2013 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2013 MPS. All Rights Reserved. 10