MP2208 16V, 4A, 600kHz Synchronous Step-Down Converter The Future of Analog IC Technology DESCRIPTION FEATURES The MP2208 is an internally compensated 600kHz fixed frequency PWM synchronous step-down regulator. With a 3V to 6V bias supply, MP2208 operates from a 3V to 16V input and generates an adjustable output voltage from 0.8V to 0.9xVIN at up to 4A load current. The MP2208 integrates a 80mΩ high-side switch and a 80mΩ synchronous rectifier for high efficiency without an external Schottky diode. With peak current mode control and internal compensation, it can be stabilized with ceramic capacitors and small inductors. Fault condition protection includes short-circuit protection, cycle-by-cycle current limiting and thermal shutdown. 4A Output Current Input Supply Range: 3V to 16V 80mΩ Internal Power MOSFET Switches Stable with Ceramic Output Capacitors High Efficiency 600kHz Fixed Switching Frequency Adjustable Output from 0.8V to 0.9xVIN Frequency Synchronization Power Good Pin Thermal Shutdown Cycle-by-Cycle Current Limiting Short Circuit Protection 3mmx4mm 14-lead QFN Package APPLICATIONS The MP2208 is available in small 3mmx4mm 14-lead QFN packages. 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. Load Current 100 5, 10 VCC 3V to 6V 7 IN 8 BS VCC SW EN/SYNC 9 POK C6 10nF 4, 11 MP2208 13 SS 2 FB 14 AGND/PGND 1, 3, 12 VOUT 1.8V / 4A EFFICIENCY (%) VIN 3V to 16V VIN=8V VIN=12V 95 90 VIN=16V 85 80 75 VOUT=3.3V VCC=5V 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 LOAD CURRENT (A) MP2208 Rev. 0.92 5/7/2012 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 1 MP2208 – 16V, 4A, 600KHz SYNCHRONOUS STEP-DOWN CONVERTER ORDERING INFORMATION Part Number* MP2208DL Package QFN14 (3mm x 4mm) Top Marking Free Air Temperature (TA) 2208 –40C to +85C * For Tape & Reel, add suffix –Z; (e.g. MP2208DL–Z); For RoHS Compliant Packaging, add suffix –LF; (e.g. MP2208DL–LF–Z) PACKAGE REFERENCE 1 14 2 13 3 12 4 11 5 10 6 9 7 8 ABSOLUTE MAXIMUM RATINGS (1) IN to GND .................................... –0.3V to +18V SW to GND .......................... –0.3V to VIN + 0.3V ............................. -2.5V to VIN + 2.5V for < 50ns FB, EN/SYNC, VCC to GND .......... –0.3V to +6.5V BS to SW .................................... –0.3V to +6.5V Continuous Power Dissipation (TA = +25°C) (2) …………………………………………..…....2.6W Junction Temperature ...............................150°C Lead Temperature ....................................260°C Storage Temperature ............... –65°C to +150°C Recommended Operating Conditions (3) Supply Voltage VIN .............................. 3V to 16V Bias Voltage VCC ................................... 3V to 6V Output Voltage VOUT .................. 0.8V to 0.9 x VIN Max Operating Junct. Temp. (TJ) .......... +125C EN/SYNC Voltage .................. No more than VCC MP2208 Rev. 0.92 5/7/2012 Thermal Resistance (4) θJA θJC QFN14 (3mm x 4mm) ............. 48 ...... 11 ... 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. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 2 MP2208 – 16V, 4A, 600KHz SYNCHRONOUS STEP-DOWN CONVERTER ELECTRICAL CHARACTERISTICS VIN = 12V, VCC = VEN = 3.6V, TA = +25C, unless otherwise noted. Parameters VCC Supply Current VCC Shutdown Current VCC Undervoltage Lockout Threshold VCC Undervoltage Lockout Hysteresis IN Under voltage lockout threshold IN Under voltage lockout hysteresis Regulated FB Voltage FB Input Current EN High Threshold EN Low Threshold Soft-Start Charging Current High-Side Switch On-Resistance Low-Side Switch On-Resistance SW Leakage Current Oscillator Frequency Synch Frequency (5) Minimum On Time Maximum Duty Cycle Thermal Shutdown Threshold High-Side Switch Current Limit Low-Side Switch Current Limit Minimum On Time Maximum Duty Cycle Thermal Shutdown Threshold Condition Min Max VEN = 0V, VIN = 12V, VCC = 6V Typ 750 1 Units μA μA Rising Edge 2.8 2.95 V 200 Rising Edge 2.85 mV 2.95 300 TA = +25°C –40°C ≤ TA ≤ +85°C VFB = 0.85V –40°C ≤ TA ≤ +85°C –40°C ≤ TA ≤ +85°C ISW = 300mA ISW = –300mA VEN = 0V; VIN = 12V; VSW = 0V or 12V 0.778 0.770 –50 1.6 0.794 0.810 0.818 50 5 80 80 600 50 90 150 6 2 50 Hysteresis = 20°C Sourcing Sinking 90 Hysteresis = 20°C mV 0.4 –10 450 0.5 150 V 10 750 2 V V nA V V µA mΩ mΩ μA kHz MHz ns % °C A A ns % °C Note: 5) Guaranteed by design. MP2208 Rev. 0.92 5/7/2012 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 3 MP2208 – 16V, 4A, 600KHz SYNCHRONOUS STEP-DOWN CONVERTER PIN FUNCTIONS Pin # 1, 3, 12 2 4, 11 5, 10 6 7 8 9 13 14 Name PGND, AGND Description Ground. Connect these pins with larger copper areas to the negative terminals of the input and output capacitors. Soft-Start Input. Place a capacitor from SS to AGND. The SS pin sources 5μA. As the SS SS voltage rises, the feedback threshold voltage increases to limit the inrush current during start-up. Do not leave this pin open. 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. This supplies power to the high side switch. A decoupling capacitor to ground IN is required close to this pin to reduce switching spikes. N/C No Connect. Bootstrap. A capacitor between this pin and SW provides a floating supply for the high-side BS gate driver. Bias Supply. This supplies power to both the internal control circuit and the gate drivers. A VCC decoupling capacitor to ground is required close to this pin. Power Okay Pin. Open drain power Good output. “HIGH” input indicates VOUT is within ±10% POK window, “LOW” output indicates VOUT is out of ±10% window. 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 500kHz to 2MHz clock signal to this pin synchronizes the internal oscillator frequency to the external source. Feedback. This is the input to the error amplifier. An external resistive divider connected FB between the output and GND is compared to the internal 0.8V reference to set the regulation voltage. Don’t apply a voltage more than VCC to this pin. MP2208 Rev. 0.92 5/7/2012 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 4 MP2208 – 16V, 4A, 600KHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS VCC = 5V, VOUT = 1.8V, TA = +25ºC, unless otherwise noted. Switching Waveform Switching Waveform VIN=5V,IO=0A VIN=12V,IO=0A VO/AC 10mV/div. VO/AC 10mV/div. VSW VSW 2V/div. 5V/div. IL 500mA/div. 500mA/div. Switching Waveform Switching Waveform VIN=5V,IO=4A VIN=12V,IO=4A VO/AC 10mV/div. VO/AC 10mV/div. VSW VSW 2V/div. 5V/div. IL IL 5A/div. VEN 5V/div. VO 1V/div. VSW 10V/div. IL 2A/div. MP2208 Rev. 0.92 5/7/2012 5A/div. Enable Start-up Enable Start-up VIN=12V,IO=0A VIN=12V,IO=4A VEN 5V/div. VO 1V/div. VSW 10V/div. IL 5A/div. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 5 MP2208 – 16V, 4A, 600KHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS VCC = 5V, VOUT = 1.8V, TA = +25ºC, unless otherwise noted. (continued) Enable Shut-down Enable Shut-down VIN=12V,IO=0A VIN=12V,IO=4A VEN VEN 5V/div. 5V/div. VO VO 1V/div. 1V/div. VSW VSW 10V/div. 10V/div. IL IL 5A/div. 1A/div. 400ms/div. Short Circuit Protection Short Circuit Recovery VIN=12V VIN=12V VO VO 1V/div. 1V/div. VSW VSW 10V/div. 10V/div. IL IL 5A/div. 5A/div. 10ms/div. 2ms/div. Load Transient VO/AC 100mV/div. IL 2A/div. MP2208 Rev. 0.92 5/7/2012 Load Transient VO/AC 100mV/div. IL 2A/div. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 6 MP2208 – 16V, 4A, 600KHz SYNCHRONOUS STEP-DOWN CONVERTER FUNCTIONAL BLOCK DIAGRAM VCC POK UVLO 0.88V UVLO IN + -- EN IN + -- 0.72V BS EN/SYNC LOGIC EN EXCLK LOGIC CLK OSC + -- EN/SYNC PWM CURRENT COMPARATOR SW SLOPE SW 0.5pF 1.2 MEG 17pF FB 0.8V -+ + COMP SLOPE COMPENSATION AND PEAK CURRENT LIMIT GND GND SS Figure 1—Functional Block Diagram MP2208 Rev. 0.92 5/7/2012 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 7 MP2208 – 16V, 4A, 600KHz SYNCHRONOUS STEP-DOWN CONVERTER OPERATION PWM Control The MP2208 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 MP2208. The loop bandwidth is adjusted by changing the upper resistor value of the resistor divider at the FB pin. The internal compensation in the MP2208 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 4us shuts down the part; forcing this pin above 1.6V for longer than 4μs turns on the part. Applying a 0.5MHz 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. For automatic start up, connect this pin to VCC with a pull-up resistor; don’t apply a voltage more than VCC to this pin. Soft-Start and Output Pre-Bias Startup The soft start time can be adjusted by connecting a capacitor from this pin to ground. When the soft-start period starts, an internal 5μA current source begins charging the external capacitor. During soft-start, the voltage on the soft-start capacitor is connected to the non-inverting input MP2208 Rev. 0.92 5/7/2012 of the error amplifier. The soft-start 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 no inverting error amplifier input. The soft-start time can be calculated as follows: t ss (ms) = 0.8V Css (nF) 5μA If the output of the MP2208 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 MP2208 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 MP2208 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 POK output change its state. Connect this pin to VCC through a pull-up resistor to get a proper power good output. 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 high-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. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 8 MP2208 – 16V, 4A, 600KHz SYNCHRONOUS STEP-DOWN CONVERTER Input UVLO Both VCC and IN pins have input UVLO detection. Until both VCC and IN voltage exceed under voltage lockout threshold, the parts remain in shutdown condition. There are also under voltage lockout hysesteres at both VCC and IN pins. MP2208 Rev. 0.92 5/7/2012 VCC Power Supply VCC is the power supply of both the internal control circuit and the gate drivers. Generally, the VCC power supply could be provided directly by a proper power rail or generated from other VCC generation circuits. For instance, figure 4 shows a typical VCC generation circuit for VOUT=5V application. It is noteworthy that the voltage applied on the VCC pin should never be higher than 6V. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 9 MP2208 – 16V, 4A, 600KHz SYNCHRONOUS STEP-DOWN CONVERTER APPLICATION INFORMATION fESR 1 2 RESR CO Setting the Output Voltage For example, choose fC=50kHz with ceramic The external resistor divider sets the output capacitor, CO=47uF, R1 is estimated to be voltage (see Figure 1). The feedback resistor R1 523KΩ. R2 is then given by: also sets the feedback loop bandwidth with the R1 internal compensation network (see Figure 1). R2 V The relation between R1 and feedback loop OUT 1 bandwidth (fC), output capacitance (CO) is as 0.8V follows: Table 1—Resistor Selection vs. Output 6 Voltage Setting 1.24 10 R1(K) fC (KHz) CO (uF) VOUT R1 R2 COUT L (μH) (V) (kΩ) (kΩ) (ceramic) The recommended feedback loop bandwidth (fC) 1.2 499 1000 2.2μH-6.8μH 47μF is no higher than 1/10th of switching frequency of MP2208. In the case of ceramic capacitor as CO, 1.5 499 562 2.2μH-6.8μH 47μF it’s usually set to be in the range of 30kHz and 1.8 499 402 2.2μH-6.8μH 47μF 50kHz for optimal transient performance and 3.3 499 158 3.3μH-6.8μH 47μF good phase margin. If electrolytic capacitor is 5 499 95.3 4.7μH-10μH 47μF used, the recommended loop bandwidth is no higher than 1/4th of the ESR zero frequency (fESR). fESR is given by: Table 2—Suggested Surface Mount Inductors Manufacturer Part Number Inductance (μH) Max DCR (mΩ) Current Rating (A) Dimensions L x W x H (mm3) FDA1055-3R3M D128C-931AS-4R7M 3.3 4.7 7.3 9.6 11.7 8.7 10.8x11.6x5.5 12.3x12.3x8 744314330 7447797470 3.3 4.7 9.6 27 8 8 7x6.9x5 10x10x4.3 ULF100457-3R3N6R9 VLF12060T-4R7N7R7 3.3 4.7 11.6 11.6 7.5 9.1 10x9.7x4.5 12.3x12x6 TOKO Wurth Electronics TDK Selecting the Inductor A 2.2μH 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 <10mΩ. See Table 2 for recommended inductors and manufacturers. For most designs, the inductance value can be derived from the following equation: L VOUT x(VIN VOUT ) VIN xIL xfOSC where ΔIL is Inductor Ripple Current. Choose inductor ripple current approximately 30% of the maximum load current, 4A. The maximum inductor peak current is MP2208 Rev. 0.92 5/7/2012 IL 2 Under light load conditions, larger inductance is recommended for improved efficiency IL(MAX) ILOAD 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 47μF capacitor is sufficient. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 10 MP2208 – 16V, 4A, 600KHz SYNCHRONOUS STEP-DOWN CONVERTER 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. 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. 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 larger than 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. MP2208 Rev. 0.92 5/7/2012 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 as follows. Here, the typical application circuit is taken as an example to illustrate the key layout rules should be followed. 1) For MP2208, a PCB layout with >=4 layers is recommended. 2) The high current paths (GND, IN and SW) should be placed very close to the device with short, direct and wide traces. 3) Two input ceramic capacitors (2 x (10μF~22μF)) are strongly recommended to be placed on both sides of the MP2208DL package and keep them as close as possible to the “IN” and “GND” pins. 4) A RC low pass filter is recommended for VCC supply. The VCC decoupling capacitor must be placed as close as possible to “VCC” pin and “GND” pin. 5) The external feedback resistors shall be placed next to the FB pin. Keep the FB trace as short as possible. 6) Keep the switching node SW short and away from the feedback network. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 11 MP2208 – 16V, 4A, 600KHz SYNCHRONOUS STEP-DOWN CONVERTER Top layer Inner layer-1 Inner layer-2 Bottom layer Figure 2―Recommended PCB Layout MP2208 Rev. 0.92 5/7/2012 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 12 MP2208 – 16V, 4A, 600KHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL APPLICATION CIRCUIT Vin 3V to 16V Vcc 2.5V to 6V R4 10 C1 22uF C2 22uF 5,10 8 13 R3 100k 9 R5 100k 7 BS IN Vcc C4 1uF C5 100nF SW 4,11 Vout 1.8V/4A D1 B0530 MP2208 EN/SYNC L1 3.3uH FB POK SS AGND/PGND R1 499k 14 2 C3 47uF R2 402k C6 10nF 1,3,12 Figure 3―Typical Application Circuit of MP2208 D2 B0530 Vin 9V to 16V C1 22uF R4 10k C2 22uF 5,10 8 Z1 4.7V Q1 MMBT3904 C4 1uF 13 R3 100k R5 100k C5 100nF 9 IN BS Vcc SW 4,11 D1 B0530 MP2208 EN/SYNC L1 4.7uH FB POK SS AGND/PGND 1,3,12 14 2 C6 10nF Vout 5V/4A R1 499k R2 95.3k C3 47uF Figure 4―MP2208 with a Vcc Generation Circuit MP2208 Rev. 0.92 5/7/2012 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 13 MP2208 – 16V, 4A, 600KHz SYNCHRONOUS STEP-DOWN CONVERTER PACKAGE INFORMATION 3mm x 4mm QFN14 2.90 3.10 1.60 1.80 0.30 0.50 PIN 1 ID MARKING PIN 1 ID SEE DETAIL A 1 14 0.18 0.30 3.20 3.40 3.90 4.10 PIN 1 ID INDEX AREA 0.50 BSC 8 TOP VIEW 7 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 BE0.10 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. MP2208 Rev. 0.92 5/7/2012 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2012 MPS. All Rights Reserved. 14