MP2119 2A, 6V Synchronous Step-Down Switching Regulator The Future of Analog IC Technology DESCRIPTION FEATURES The MP2119 is an internally compensated 1.5MHz fixed frequency PWM synchronous step-down regulator. MP2119 operates from a 2.7V to 6V input and generates an output voltage as low as 0.8V. • • • • • • • • • • • • The MP2119 integrates a 100mΩ high-side switch and a 100mΩ synchronous rectifier for high efficiency without an external Schottky diode. With peak current mode control and internal compensation, the MP2119 based solution delivers a very compact footprint with a minimum component count. The MP2119 is available in a small 3mm x 3mm QFN package. 2A Output Current Input Operation Range: 2.7V to 6V All Ceramic Capacitor Design 1.5MHz Fixed Switching Frequency Adjustable Output from 0.8V to 0.9xVIN Internal Soft-Start Frequency Synchronization Input Power Good Output Thermal Shutdown Cycle-by-Cycle Current Limiting Hiccup Short Circuit Protection 3mm x 3mm QFN Package APPLICATIONS • • • • µP/ASIC/DSP/FPGA Core and I/O Supplies Printers and LCD TVs Network and Telecom Equipment Point of Load Regulators “MPS” and “The Future of Analog IC Technology” are Trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION Efficiency vs. Output Current VIN 2.7V to 6V 47 POK IN C3 100nF BS POK VOUT 1.8V / 2A SW MP2119 OFF ON 1.2 EN/SYNC GND 400 FB 310 47 EFFICIENCY (%) 100 80 VIN = 5V, VOUT =1.8V VIN = 3.3V, VOUT =1.8V 60 40 20 0 0 MP2119 Rev. 0.94 4/22/2011 0.5 1.0 1.5 OUTPUT CURRENT (A) www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 2.0 1 MP2119 – 2A, 6V SYNCHRONOUS STEP-DOWN SWITCHING REGULATOR ORDERING INFORMATION Part Number* MP2119DQ Package QFN10 (3mm x 3mm) Top Marking Free Air Temperature (TA) U8 -40°C to +85°C * For Tape & Reel, add suffix –Z (e.g. MP2119DQ–Z). For RoHS compliant packaging, add suffix –LF (e.g. MP2119DQ–LF–Z) PACKAGE REFERENCE TOP VIEW FB 1 GND 2 SW 3 IN 4 BS 5 11 EXPOSED PAD 10 EN/SYNC 9 GND 8 SW 7 IN 6 POK EXPOSED PAD ON BACKSIDE ABSOLUTE MAXIMUM RATINGS (1) IN to GND .................................... -0.3V to +6.5V SW to GND ........................... -0.3V to VIN + 0.3V SW to GND ............ -2.5V to VIN+2.5V for <50nS FB, EN/SYNC, POK to GND ........... -0.3V to +6.5V BS to SW ..................................... -0.3V to +6.5V (2) Continuous Power Dissipation (TA = +25°C) ………………………………………………....2.5W Junction Temperature ...............................150°C Lead Temperature ....................................260°C Storage Temperature ............... -65°C to +150°C Recommended Operating Conditions (3) Supply Voltage VIN ............................. 2.7V to 6V Output Voltage VOUT .................. 0.8V to 0.9 x VIN Operating Junct. Temp (TJ)...... -40°C to +125°C MP2119 Rev. 0.94 4/22/2011 Thermal Resistance (4) θJA θJC QFN10 (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. © 2011 MPS. All Rights Reserved. 2 MP2119 – 2A, 6V SYNCHRONOUS STEP-DOWN SWITCHING REGULATOR ELECTRICAL CHARACTERISTICS (5) VIN = VEN = 3.6V, TA = +25°C, unless otherwise noted. Parameters Supply Current Shutdown Current IN Undervoltage Lockout Threshold IN Undervoltage Lockout Hysteresis Regulated FB Voltage FB Input Current EN High Threshold EN Low Threshold Internal Soft-Start Time High-Side Switch On-Resistance Low-Side Switch On-Resistance SW Leakage Current BS Under Voltage Lockout Threshold High-Side Switch Current Limit Low-Side Switch Current Limit Oscillator Frequency Maximum Synch Frequency Minimum Synch Frequency Minimum On Time Maximum Duty Cycle POK Upper Trip Threshold POK Lower Trip Threshold POK Output Voltage Low POK Deglitch Timer Thermal Shutdown Threshold Condition VEN = VIN VFB = 0.85V VEN = 0V, VIN = 5V Min Rising Edge Typ Max 750 µA 1 µA 2.59 2.69 210 TA = +25°C VFB = 0.85V -40°C ≤ TA ≤ +85°C -40°C ≤ TA ≤ +85°C ISW = 300mA ISW = –300mA VEN = 0V; VIN = 5V VSW = 0V or 5V Sourcing Sinking 0.776 0.800 ±50 0.824 0.4 V nA V V µs mΩ mΩ 10 µA 120 100 100 –10 1.2 FB respect to the nominal value FB respect to the nominal value ISINK = 5mA Hysteresis = 20°C V mV 1.6 TBD Units 1.8 V 3.5 3.5 1.5 2 1 50 90 10 -10 A A MHz MHz MHz ns % % % V µs °C 1.8 0.4 30 150 Note: 5) Production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization. MP2119 Rev. 0.94 4/22/2011 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 3 MP2119 – 2A, 6V SYNCHRONOUS STEP-DOWN SWITCHING REGULATOR PIN FUNCTIONS Pin # 1 2, 9 3, 8 4, 7 5 6 10 11 Name Description Feedback. This is the input to the error amplifier. An external resistive divider connects this FB pin between the output and GND. The voltage on the FB pin compares to the internal 0.8V reference to set the regulation voltage. Ground. Connect these pins with larger copper areas to the negative terminals of the input GND and output capacitors. Switch Node Connection to the Inductor. These pins connect to the internal high and lowSW side power MOSFET switches. All SW pins must be connected together externally. Input Supply. A decoupling capacitor to ground is required close to these pins to reduce IN switching spikes. Bootstrap. A capacitor between this pin and SW provides a floating supply for the high-side BS gate driver. Open Drain Power Okay Output. “HIGH” output indicates VOUT is within ±10% window. POK “LOW” output indicates VOUT is out of ±10% window. POK is pulled down in shutdown. Enable and Frequency Synchronization Input Pin. Forcing this pin below 0.4V shuts down EN/SYNC the part. Forcing this pin above 1.6V turns on the part. Applying a 1MHz to 2MHz clock signal to this pin synchronizes the internal oscillator frequency to the external source. Exposed Connect exposed pad to ground plane for optimal thermal performance. Pad MP2119 Rev. 0.94 4/22/2011 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 4 MP2119 – 2A, 6V SYNCHRONOUS STEP-DOWN SWITCHING REGULATOR TYPICAL PERFORMANCE CHARACTERISTICS VIN = 5V, VOUT = 1.8V, TA = +25ºC, unless otherwise noted. Steady State Operation Steady State Operation No Load Steady State Operation Half Load VOUT 10mV/div. VOUT 10mV/div. Inductor 1A/div. Inductor 1A/div. VSW 5V/div. VSW 5V/div. 400ns/div Full Load VOUT 10mV/div. Inductor 1A/div. VSW 5V/div. 400ns/div 400ns/div Start-up through enable Load Transient No Load 1A-2A Step Resistive Load VOUT 100mV/div. VOUT 1V/div. VPOK 2V/div. Inductor 1A/div. VEN 2V/div. 200ns/div MP2119 Rev. 0.94 4/22/2011 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 5 MP2119 – 2A, 6V SYNCHRONOUS STEP-DOWN SWITCHING REGULATOR TYPICAL PERFORMANCE CHARACTERISTICS VIN = 5V, VOUT = 1.8V, TA = +25ºC, unless otherwise noted. Steady State Operation Shut Down through Enable Shut Down through Enable Full Load No Load Full Load VOUT 1V/div. VOUT 1V/div. VPOK 2V/div. VOUT 1V/div. VEN 2V/div. VEN 2V/div. VPOK 2V/div. v VEN 2V/div. VPOK 2V/div. 400ms/div 1ms/div Short Circut Protection Short Circuit Recovery VIN=5V,VOUT=1.8V VIN=5V,VOUT=1.8V VOUT 1V/div. VSW 5V/div. VOUT 10mV/div. VSW 5V/div. Inductor 2A/div. Inductor 1A/div. v MP2119 Rev. 0.94 4/22/2011 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 1ms/div 6 MP2119 – 2A, 6V SYNCHRONOUS STEP-DOWN SWITCHING REGULATOR FUNCTION BLOCK DIAGRAM POK 0.88V IN + -- EN IN + -- 0.72V BS EN EXCLK LOGIC CLK OSC + -- EN/SYNC LOGIC EN/SYNC PWM CURRENT COMPARATOR SW SLOPE SW 0.5pF 1.2 MEG 17pF FB 0.8V -+ + COMP SLOPE COMPENSATION AND PEAK CURRENT LIMIT SOFT -START GND GND Figure 1—Function Block Diagram MP2119 Rev. 0.94 4/22/2011 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 7 MP2119 – 2A, 6V SYNCHRONOUS STEP-DOWN SWITCHING REGULATOR FUNCTIONAL DESCRIPTION PWM Control The MP2119 is a constant frequency peakcurrent-mode control PWM switching regulator. Refer to the functional block diagram. The high side N-Channel DMOS power switch turns on at the beginning of each clock cycle. The current in the inductor increases until the PWM current comparator trips to turn off the high side DMOS switch. The peak inductor current at which the current comparator shuts off the high side power switch is controlled by the COMP voltage at the output of feedback error amplifier. The transconductance from the COMP voltage to the output current is set at 11.25A/V. This current-mode control greatly simplifies the feedback compensation design by approximating the switching converter as a single-pole system. Only Type II compensation network is needed, which is integrated into the MP2119. The loop bandwidth is adjusted by changing the upper resistor value of the resistor divider at the FB pin. The internal compensation in the MP2119 simplifies the compensation design, minimizes external component counts, and keeps the flexibility of external compensation for optimal stability and transient response. Enable and Frequency Synchronization (EN/SYNC PIN) This is a dual function input pin. Forcing this pin below 0.4V for longer than 4µs shuts down the part; forcing this pin above 1.6V for longer than 4µs turns on the part. Applying a 1MHz to 2MHz clock signal to this pin also synchronizes the internal oscillator frequency to the external clock. When the external clock is used, the part turns on after detecting the first few clocks regardless of duty cycles. If any ON or OFF period of the clock is longer than 4µs, the signal will be intercepted as an enable input and disables the synchronization. period lasts until the voltage on the soft-start capacitor exceeds the reference voltage of 0.8V. At this point the reference voltage takes over at the non-inverting error amplifier input. The softstart time is internally set at 120µs. If the output of the MP2119 is pre-biased to a certain voltage during startup, the IC will disable the switching of both high-side and low-side switches until the voltage on the internal soft-start capacitor exceeds the sensed output voltage at the FB pin. Over current Protection The MP2119 offers cycle-to-cycle current limiting for both high-side and low-side switches. The high-side current limit is relatively constant regardless of duty cycles. When the output is shorted to ground, causing the output voltage to drop below 50% of its nominal output, the IC is shut down momentarily and begins discharging the soft start capacitor. It will restart with a full soft-start when the soft- start capacitor is fully discharged. This hiccup process is repeated until the fault is removed. Power Good Output (POK PIN) The MP2119 includes an open-drain Power Good output that indicates whether the regulator output is within ±10% of its nominal output. When the output voltage moves outside this range, the POK output is pulled to ground. There is a 30µs deglitch time when the POK output change its state. Bootstrap (BST PIN) The gate driver for the high-side N-channel DMOS power switch is supplied by a bootstrap capacitor connected between the BS and SW pins. When the low-side switch is on, the capacitor is charged through an internal boost diode. When the high-side switch is off and the low-side switch turns on, the voltage on the bootstrap capacitor is boosted above the input voltage and the internal bootstrap diode prevents the capacitor from discharging. Soft-Start and Output Pre-Bias Startup When the soft-start period starts, an internal current source begins charging an internal softstart capacitor. During soft-start, the voltage on the soft-start capacitor is connected to the noninverting input of the error amplifier. The soft-start MP2119 Rev. 0.94 4/22/2011 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 8 MP2119 – 2A, 6V SYNCHRONOUS STEP-DOWN SWITCHING REGULATOR APPLICATION INFORMATION Output Voltage Setting The external resistor divider sets the output voltage (see Page 1). The feedback resistor R1 also sets the feedback loop bandwidth with the internal compensation (refer to description function). The relation between R1 and feedback loop bandwidth (fC), output capacitance (CO) is as following: 1.24 × 106 R1(kΩ) = fC (kHz) × CO (uF) The feedback loop bandwidth (fC) is no higher than 1/10 of switching frequency of MP2119. In the case of ceramic capacitor as CO, it’s usually set to be in the range of 50kHz and 150kHz for optimal transient performance and good phase margin. If electrolytic capacitor is used, the loop bandwidth is no higher than 1/4 of the ESR zero frequency (fESR). fESR is given by: 1 fESR = 2π × RESR × CO For example, choose fC=70kHz with ceramic capacitor, CO=47uF, R1 is estimated to be 400kΩ. R2 is then given by: R1 R2 = VOUT -1 0.8V Table 1—Resistor Selection vs. Output Voltage Setting VOUT (V) R1 (kΩ) R2 (kΩ) L (µH) COUT (ceramic) 1.2 1.5 1.8 2.5 3.3 400 400 400 400 400 806 453 316 187 127 0.47µH-1µH 0.47µH-1µH 0.47µH-1µH 0.47µH-1µH 0.47µH-1µH 47µF 47µF 47µF 47µF 47µF Inductor Selection A 0.47µH to 1µH 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 <10mΩ. For most designs, the inductance value can be derived from the following equation: VOUT × (VIN - VOUT) L= VIN × ∆IL × fOSC Where ∆IL is Inductor Ripple Current. Choose inductor ripple current approximately 30% of the maximum load current. The maximum inductor peak current is: ∆IL IL(MAX) = ILOAD + 2 Under light load conditions, larger inductance is recommended for improved efficiency. Input Capacitor Selection The input capacitor reduces the surge current drawn from the input and the 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 source. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. For most applications, a 47µF capacitor is sufficient. Output Capacitor Selection The output capacitor keeps output voltage ripple small and ensures a stable regulation loop. The output capacitor impedance shall be low at the switching frequency. Ceramic capacitors with X5R or X7R dielectrics are recommended. If electrolytic capacitor is used, pay attention to output ripple voltage, extra heating, and the selection of feedback resistor R1 (refer to “Output Voltage Setting” section) due to large ESR of electrolytic capacitor. The output ripple ∆VOUT is approximately: ∆VOUT ≤ MP2119 Rev. 0.94 4/22/2011 VOUT × (VIN - VOUT) VIN × fOSC × L × (ESR + www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 1 8 × fOSC × CO ) 9 MP2119 – 2A, 6V SYNCHRONOUS STEP-DOWN SWITCHING REGULATOR External Schottky Diode For this part, an external schottky diode is recommended to be placed close to "SW" and "GND" pins, especially when the output current is close to 2A. With the external schottky diode, the voltage spike and negative kick on "SW" pin can be minimized; moreover, the conversion efficiency can also be improved a little. For the external schottky diode selection, it's noteworthy that the maximum reverse voltage rating of the external diode should be larger than the maximum input voltage. As for the current rating of this diode, 0.5A rating should be sufficient. Top Layer PCB Layout 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 as follows. Here, the typical application circuit is taken as an example to illustrate the key layout rules should be followed. 1) For MP2119, a PCB layout with more than (or) four layers is recommended. Inner Layer1 2) The high current paths (GND, IN and SW) should be placed very close to the device with short, direct and wide traces. 3) For MP2119, two input ceramic capacitors (2 x (10µF~22µF)) are strongly recommended to be placed on both sides of the MP2119 package and keep them as close as possible to the “IN” and “GND” pins. If this placement is not possible, a ceramic cap (10µF~47µF) must be placed across PIN7-“IN”and PIN9-“GND” since the internal Vcc supply is powered from PIN7, and good decoupling is needed to avoid any interference issues. Inner Layer2 4) The external feedback resistors shall be placed next to the FB pin. Keep the FB trace as short as possible. Don’t place test points on FB trace if possible. 5) Keep the switching node SW short and away from the feedback network. MP2119 Rev. 0.94 4/22/2011 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 10 MP2119 – 2A, 6V SYNCHRONOUS STEP-DOWN SWITCHING REGULATOR Bottom Layer Figure2―Recommended PCB Layout of MP2119 Table 2—Suggested Surface Mount Inductors Part Number Inductance (µH) Max DCR (mΩ) Current Rating (A) Dimensions L x W x H (mm3) 744310055 744310095 0.55 0.95 4.5 7.4 14 11 7×6.9×3 7×6.9×3 B1015AS-1R0N 1 11 6.9 8.4×8.3×4 Manufacturer Wurth Electronics TOKO TYPICAL APPLICATION CIRCUIT Vin 2.7V to 5.5V C1 10uF C2 10uF 6 R4 100k R3 100k 4,7 C4 100nF 5 IN BS SW POK 3,8 MP2119 10 EN/SYNC FB GND 2,9,11 1 D1 B0530 L1 1uH R1 400k R2 316k Vout 1.8V/2A C3 47uF Figure3―Typical Application Circuit of MP2119 MP2119 Rev. 0.94 4/22/2011 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 11 MP2119 – 2A, 6V SYNCHRONOUS STEP-DOWN SWITCHING REGULATOR PACKAGE INFORMATION 3mm x 3mm QFN10 2.90 3.10 0.30 0.50 PIN 1 ID MARKING 0.18 0.30 2.90 3.10 PIN 1 ID INDEX AREA 1.45 1.75 PIN 1 ID SEE DETAIL A 10 1 2.25 2.55 0.50 BSC 5 6 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 0.70 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) DRAWING CONFORMS TO JEDEC MO-229, VARIATION VEED-5. 5) DRAWING IS NOT TO SCALE. 1.70 0.25 2.50 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. MP2119 Rev. 0.94 4/22/2011 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2011 MPS. All Rights Reserved. 12