MP2205A 16V, 2.5A, 1.3MHz Synchronous Step-Down Converter The Future of Analog IC Technology DESCRIPTION FEATURES The MP2205A is an internally compensated 1.3MHz fixed frequency PWM synchronous step-down regulator with a 3V to 6V bias supply (VCC). MP2205A operates from a 3V to 16V input and generates an adjustable output voltage from 0.8V to 0.9xVIN at up to 2.5A load current. • • • • • • • • • • • • • • The MP2205A integrates an 80mΩ high-side switch and an 80mΩ synchronous rectifier for high efficiency without an external Schottky diode. With peak current mode control and internal compensation, it is stable with a output ceramic capacitor and a small inductor. Fault protection includes hiccup short-circuit protection, cycle-by-cycle current limiting and thermal shutdown. Other features include frequency synchronization and internal softstart. 2.5A Output Current Input Supply Range: 3V to 16V 80mΩ Internal Power MOSFET Switches All Ceramic Output Capacitors Design Up to 95% Efficiency 1.3MHz Fixed Switching Frequency Adjustable Output from 0.8V to 0.9xVIN Internal Soft-Start Power Good Pin Frequency Synchronization Input Thermal Shutdown Cycle-by-Cycle Current Limiting Hiccup Short Circuit Protection 14-Lead, 3mm x 4mm QFN Package APPLICATIONS • • • • The MP2205A is available in a small 3mm x 4mm 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 VIN 3V to 16V VCC 3V to 6V C1 33uF 5,10 8 C4 1uF OFF ON 7 IN C3 100nF BS VCC SW 4,11 MP2205A 13 9 EN/SYNC L1 1uH C6 560PF FB POK GND VOUT 1.8V / 2.5A 14 C2 47uF 1,3,12 MP2205A Rev. 0.9 9/1/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 1 MP2205A – 16V, 2.5A, 1.3MHz SYNCHRONOUS STEP-DOWN CONVERTER ORDERING INFORMATION Part Number* MP2205ADL Package QFN14 (3mm x 4mm) Top Marking Free Air Temperature (TA) MP2205A -40°C to +85°C * For Tape & Reel, add suffix –Z (eg. MP2205ADL–Z). For RoHS Compliant Packaging, add suffix –LF (eg. MP2205ADL–LF–Z) PACKAGE REFERENCE TOP VIEW PIN 1 ID AGND 1 14 FB N/C 2 13 EN/SYNC PGND 3 12 PGND SW 4 11 SW IN 5 10 IN N/C 6 9 POK BS 7 8 VCC EXPOSED PAD ON BACKSIDE 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 Operating Junct. Temp (TJ)...... -40°C to +125°C MP2205A Rev. 0.9 9/1/2010 Thermal Resistance (4) θJA θJC QFN14 (3mm x 4mm) ............. 48 ...... 10... °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-to-ambient 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 MP2205A – 16V, 2.5A, 1.3MHz SYNCHRONOUS STEP-DOWN CONVERTER ELECTRICAL CHARACTERISTICS (5) VCC = 3.6V, VIN=12V, TA = +25°C, unless otherwise noted. Parameters VCC Supply Current VCC Shutdown Current VCC Under Voltage Lockout Threshold VCC Under Voltage Lockout Hysteresis IN Shutdown Current IN Under Voltage Lockout Threshold, Rising Edge IN Under Voltage Lockout Hysteresis Regulated FB Voltage Condition VEN = VCC VFB = 0.85V VEN = 0V, VCC= 6V Min Typ Rising Edge VEN = 0V TA = +25°C –40°C ≤ TA ≤ +85°C VFB = 0.85V –40°C ≤ TA ≤ +85°C –40°C ≤ TA ≤ +85°C FB Input Current EN High Threshold EN Low Threshold Internal Soft-Start Time High-Side Switch On-Resistance ISW = 300mA Low-Side Switch On-Resistance ISW = –300mA VEN = 0V; VIN = 12V SW Leakage Current VSW = 0V or 12V BS Under Voltage Lockout Threshold High-Side Switch Current Limit Sourcing Low-Side Switch Current Limit Sinking Oscillator Frequency Maximum Synch Frequency Minimum Synch Frequency Minimum On Time Maximum Duty Cycle Thermal Shutdown Threshold Hysteresis = 20°C 0.780 0.772 Max 750 μA 1 μA 2.9 V 200 mV 3 μA 2.9 V 300 mV 0.800 0.820 0.828 ±50 1.6 0.4 120 80 80 -10 1 Units 10 V V nA V V µs mΩ mΩ μA 1.8 V 4 3.5 1.3 2 1 50 90 150 A A MHz MHz MHz ns % °C 1.6 Note: 5) Production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization. MP2205A Rev. 0.9 9/1/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 3 MP2205A – 16V, 2.5A, 1.3MHz SYNCHRONOUS STEP-DOWN CONVERTER PIN FUNCTIONS Pin # 8 5, 10 4, 11 1, 3, 12 7 14 13 9 2, 6 Name Description 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. 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. 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. PGND, Ground. Connect these pins with larger copper areas to the negative terminals of the input AGND and output capacitors. Bootstrap. A capacitor between this pin and SW provides a floating supply for the high-side BS gate driver. 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. 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. POK Power Good Pin. N/C No Connect. MP2205A Rev. 0.9 9/1/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 4 MP2205A – 16V, 2.5A, 1.3MHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS VOUT = 1.8V, TA = +25ºC, unless otherwise noted. MP2205A Rev. 0.9 9/1/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 5 MP2205A – 16V, 2.5A, 1.3MHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VOUT = 1.8V, TA = +25ºC, unless otherwise noted. MP2205A Rev. 0.9 9/1/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 6 MP2205A – 16V, 2.5A, 1.3MHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VOUT = 1.8V, TA = +25ºC, unless otherwise noted. MP2205A Rev. 0.9 9/1/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 7 MP2205A – 16V, 2.5A, 1.3MHz SYNCHRONOUS STEP-DOWN CONVERTER FUNCTIONAL BLOCK DIAGRAM POK VCC UVLO UVLO IN 0.88V + 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 375k FB -+ + 0.8V COMP SLOPE COMPENSATION AND PEAK CURRENT LIMIT SOFT -START GND GND Figure 1—Functional Block Diagram MP2205A Rev. 0.9 9/1/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 8 MP2205A – 16V, 2.5A, 1.3MHz SYNCHRONOUS STEP-DOWN CONVERTER FUNCTIONAL DESCRIPTION PWM Control The MP2205A is a constant frequency peak-currentmode 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 MP2205A. The loop bandwidth is adjusted by changing the upper resistor value of the resistor divider at the FB pin. The internal compensation in the MP2205A 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 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. Soft-Start and Output Pre-Bias Startup When the soft-start period starts, an internal current source begins charging an internal soft-start capacitor. During soft-start, the voltage on the softstart capacitor is connected to the non-inverting input 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 non-inverting error amplifier input. The soft-start time is internally set at 120µs. If the output of the MP2205A is prebiased 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. MP2205A Rev. 0.9 9/1/2010 Over Current Protection The MP2205A offers cycle-to-cycle current limiting for both high-side and low-side switches. The highside current limit is relatively constant regardless of duty cycles. When the output is shorted to ground, causing the output voltage to drop below 70% 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 The MP2205A 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 on and the low-side switch turns off, the voltage on the bootstrap capacitor is boosted above the input voltage and the internal bootstrap diode prevents the capacitor from discharging. No external bootstrap diode is required for typical applications. For applications with low input VCC voltage or where output voltage is very close to input voltage, an external Schottky diode may be connected from the VCC to BS pins to charge the bootstrapped capacitor more strongly for increased gate drive voltage. When using the external bootstrap diode, a resistor at the regulator output or a minimal load current may be required as the bootstrapped capacitor always see the supply voltage even when the part is disabled. 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. 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. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 9 MP2205A – 16V, 2.5A, 1.3MHz SYNCHRONOUS STEP-DOWN CONVERTER the inductance value can be derived from the following equation: APPLICATION INFORMATION Setting the Output Voltage The external resistor divider sets the output voltage (see Typical Application on page 1). R2 is given by: R2 = L= where ∆IL is Inductor Ripple Current. Choose inductor ripple current approximately 30% of the maximum load current, 2.5A.The maximum inductor peak current is: R1 VOUT −1 0.8V Table 1—Resistor Selection vs. Output Voltage Setting VOUT (V) R1 (kΩ) R2 (kΩ) 1.2 1.5 1.8 2.5 3.3 5 8.75 12.4 21.25 31.25 10 10 10 10 10 L (μH) COUT (ceramic) 0.47μH-1μH 0.47μH-1μH 0.47μH-1μH 0.47μH-1μH 0.47μH-1μH 47μF 47μF 47μF 47μF 47μF VOUT x(VIN − VOUT ) VIN xΔIL xfOSC IL(MAX) = ILOAD + ΔIL 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 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. Selecting the Inductor 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. See Table 2 for recommended inductors and manufacturers. For most designs, Table 2—Suggested Surface Mount Inductors Manufacturer Part Number Inductance (μH) Max DCR (mΩ) Current Rating (A) Dimensions L x W x H (mm3) 0.55 0.95 4.5 7.4 14 11 7×6.9×3 7×6.9×3 1 11 6.9 8.4×8.3×4 Wurth Electronics 744310055 744310095 TOKO B1015AS-1R0N MP2205A Rev. 0.9 9/1/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 10 MP2205A – 16V, 2.5A, 1.3MHz SYNCHRONOUS STEP-DOWN CONVERTER Output Capacitor Selection PC Board Layout 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. The output ripple ∆VOUT is approximately: 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 MP2205A, 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 MP2205ADL 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. ΔVOUT ≤ VOUT x(VIN − VOUT ) 1 x(ESR + ) VIN xfOSC xL 8xfOSC xC3 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. MP2205A Rev. 0.9 9/1/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 11 MP2205A – 16V, 2.5A, 1.3MHz SYNCHRONOUS STEP-DOWN CONVERTER Top Layer Inner Layer1 Bottom Layer InnerLayer2 Figure 2—Recommended PCB Layout MP2205A Rev. 0.9 9/1/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 12 MP2205A – 16V, 2.5A, 1.3MHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL APPLICATION CIRCUIT Figure 3—Typical Application Circuit of MP2205A 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 Vcc BS SW 4,11 D1 B0530 MP2205A EN/SYNC L1 1uH FB POK N/C AGND/PGND 14 2 Vout 5V/2.5A R1 10k R2 1.91k C3 47uF 1,3,12 Figure 4—MP2205A with a Vcc Generation Circuit MP2205A Rev. 0.9 9/1/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 13 MP2205A – 16V, 2.5A, 1.3MHz SYNCHRONOUS STEP-DOWN CONVERTER PACKAGE INFORMATION QFN14 (3mm x 4mm) 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 7 8 TOP VIEW BOTTOM VIEW PIN 1 ID OPTION A 0.30x45º TYP. 0.80 1.00 0.20 REF PIN 1 ID OPTION B R0.20 TYP. 0.00 0.05 SIDE VIEW DETAIL A 2.90 0.70 NOTE: 1.70 1) 2) 3) 4) 5) 0.25 ALL DIMENSIONS ARE IN MILLIMETERS. EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH. LEAD COPLANARITY SHALL BE 0.10 MILLIMETER MAX. DRAWING CONFORMS TO JEDEC MO-229, VARIATION VEED-5. DRAWING IS NOT TO SCALE. 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. MP2205A Rev. 0.9 9/1/2010 www.MonolithicPower.com MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. 14