MP3421 The Future of Analog IC Technology 5.5A, 600kHz High-Efficiency, Synchronous Step-Up Converter with True Output Disconnect in a 2mmx2mm QFN Package DESCRIPTION FEATURES The MP3421 is a high-efficiency, synchronous, current–mode, step-up converter with true output disconnect. • • • • • • • • • • • • • The MP3421 starts up from low input voltage (as low as 1.9V) while providing in-rush current limiting and output short-circuit protection. The integrated, P-channel synchronous rectifier improves efficiency and eliminates the need for an external Schottky diode; the P-channel disconnects the output load from the input during shutdown. The MP3421 has 600kHz switching frequency, which accommodates small external components. In addition, its internal compensation and soft-start functions minimize external component count. The MP3421 provides a compact solution for a 5V output, 2.1A load requirement, using a supply voltage as low as 2.8V. The MP3421 is available in a 14-pin QFN 2mmx2mm package. Support 5V/2.1A Output at 2.8V Input Up to 98% Efficiency 1.9V to 5.5V Input Range 2.5V to 5.5V Output Range Internal Synchronous Rectifier 600kHz Fixed-Switching Frequency >5.5A Switch-Current Limit Capability 43uA Quiescent Current High-Efficiency over Full-Load Range Internal Soft-start and Compensation Output-Load Disconnect from Input OCP, SCP, OVP and OTP Protection Small 2x2mm QFN14 Package APPLICATIONS • • • • • Battery-Powered Products Power Banks, Juice Packs, Battery Back-up Units USB Power Supply Consumer Electronic Accessories Tablets All MPS parts are lead-free and adhere to the RoHS directive. For MPS green status, please visit MPS website under Products, Quality Assurance page. “MPS” and “The Future of Analog IC Technology” are Registered Trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION Efficiency vs. Load Current 100 VOUT=5V VIN=4.2V 98 96 94 VIN=3.3V VIN=2.8V 92 90 88 86 84 0 0.5 1 1.5 2 2.5 LOAD CURRENT (A) MP3421 Rev. 1.0 11/13/2014 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2014 MPS. All Rights Reserved. 1 MP3421—5.5A, 600KHZ HIGH EFFICIENCY, SYNCHRONOUS, STEP-UP CONVERTER WITH OUTPUT DISCONNECT IN 2X2MM QFN PACKAGE ORDERING INFORMATION Part Number* MP3421GG Package QFN-14 (2mmX2mm) Top Marking See Below * For Tape & Reel, add suffix –Z (e.g. MP3421GG–Z) TOP MARKING DK: product code of MP3421GG; Y: year code; LLL: lot number; PACKAGE REFERENCE TOP VIEW MP3421 Rev. 1.0 11/13/2014 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2014 MPS. All Rights Reserved. 2 MP3421—5.5A, 600KHZ HIGH EFFICIENCY, SYNCHRONOUS, STEP-UP CONVERTER WITH OUTPUT DISCONNECT IN 2X2MM QFN PACKAGE ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance SW .. ......................-0.3V to +6.5V (9V for <5ns) All other Pins................................-0.3V to +6.5V Continuous Power Dissipation (TA = +25°C) (2) ........................................................... 1.56W Junction Temperature ...............................150°C Lead Temperature ....................................260°C Storage Temperature............... -65°C to +150°C QFN-14 (2mmx2mm)............. 80....... 16 °C/W Recommended Operating Conditions (3) Supply Voltage VIN ..........................1.9V to 5.5V VOUT .................................................2.5V to 5.5V Operating Junction Temp. (TJ). -40°C to +125°C MP3421 Rev. 1.0 11/13/2014 (4) θJA θJC 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. © 2014 MPS. All Rights Reserved. 3 MP3421—5.5A, 600KHZ HIGH EFFICIENCY, SYNCHRONOUS, STEP-UP CONVERTER WITH OUTPUT DISCONNECT IN 2X2MM QFN PACKAGE ELECTRICAL CHARACTERISTICS VIN = VEN = 3.3V, VOUT = 5V, TJ= -40°C to125°C, typical values are tested at TJ =25°C, unless otherwise noted. Parameters Voltage Range Start-Operating Input Voltage Symbol Condition VIN Quiescent Current IQ_NS Shutdown Current ISD IN UVLO Rising Threshold IN UVLO Falling Threshold VOUT Start-Switching Rising Threshold VUVLO_IN-R VUVLO_IN-F Min Typ 1.9 VEN=VIN=3.3V, VOUT=5V, no load Measured on OUT, TJ=25°C VEN=VIN=3.3V, VOUT=5V, no load Measured on IN VEN=VOUT=0V, Measured on IN, TJ=25°C VIN Rising TJ=25°C VIN Falling, VOUT=5V 43 Max Units 5.5 V 57 µA 0.3 1 VUVLO_OUT_R TJ=25°C µA 0.1 1 µA 1.3 650 1.6 V mV 1.7 1.79 V Step-up Converter Operation Frequency FSW Feedback Voltage VFB Feedback Input Current NMOS On-Resistance NMOS Leakage Current PMOS On-Resistance PMOS Leakage Current Maximum Duty Cycle IFB RNDS_ON IN_LK RPDS_ON IP_LK DMAX Linear-Charge Current Limit(5) ICH_LIMIT NMOS Current Limit(5) ISW_LIMIT1 ISW_LIMIT2 TJ=25°C 500 600 700 -40°C≤TJ≤125°C 440 600 760 TJ=25°C 795 807 819 -40°C≤TJ≤125°C 791 807 823 mV 1 15 100 20 0.1 95 0.7 0.2 4 50 nA mΩ nA mΩ µA % A A A A VFB=850mV VSW=5V VSW=5V, VOUT=0V 90 VOUT=1.7V VOUT=0V VIN=5V, VOUT=3.3V Duty=44%, VIN=2.8V, VOUT=5V 5.5 kHz Logic Interface EN High-Level Voltage EN Low-Level Voltage EN Input Current VEN _H VEN _L IEN 1.2 10 V V nA 150 °C 20 °C 0.4 Connect to VIN Protection Thermal Shutdown(5) Over Temperature Hysteresis (5) Notes: 5) Guaranteed by characterization, not production tested. MP3421 Rev. 1.0 11/13/2014 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2014 MPS. All Rights Reserved. 4 MP3421—5.5A, 600KHZ HIGH EFFICIENCY, SYNCHRONOUS, STEP-UP CONVERTER WITH OUTPUT DISCONNECT IN 2X2MM QFN PACKAGE TYPICAL CHARACTERISTICS VIN = VEN = 3.3V, VOUT = 5V, L = 1.5µH, TA = 25°C, unless otherwise noted. Quiescent Current vs. Input Voltage VIN>VOUT 60 60 VIN<VOUT 2 EN=LOW 50 1.6 40 40 1.2 30 30 0.8 20 20 0.4 10 1.5 2 2.5 3 3.5 4 4.5 5 5.5 INPUT VOLTAGE(V) 10 1.5 2 2.5 3 3.5 4 4.5 5 5.5 OUTPUT VOLTAGE(V) Input UVLO Threshold vs. Temperature 1 0 1.5 2 2.5 3 3.5 4 4.5 5 5.5 INPUT VOLTAGE(V) EN Threshold vs. Temperature VOUT Rising Threshold for switching vs. Temperature 2.5 0.4 Falling Threshold 0.5 Rising Threshold Falling Threshold 0.25 820 750 Frequency vs. Temperature 815 700 FREQUENCY(kHz) 805 800 795 790 650 600 550 785 780 -40 -20 0 20 40 60 80 100120140 MP3421 Rev. 1.0 11/13/2014 500 -40 -20 0 20 40 60 80 100120140 2 1.75 1.5 1.25 1 -40 -20 0 20 40 60 80 100120140 0 -40 -20 0 20 40 60 80 100120140 Feedback Voltage vs. Temperature 810 VOUT THRESHOLD(V) Rising Threshold 0.8 0.75 1 LINEAR CHARGING LIMIT(A) 1.2 EN THRESHOLD(V) 2.25 1.6 0 -40 -20 0 20 40 60 80 100120140 FB REGULATION VOLTAGE(mV) Shutdown Current vs. Input Voltage 50 2 VIN UVLO THRESHOLD(V) Quiescent Current vs. Output Voltage Linear-Charging Current Limit vs. Output Voltage 0.75 VIN=4.2V 0.5 0.25 VIN=2.8V 0 0 0.4 0.8 1.2 1.6 OUTPUT VOLTAGE(V) www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2014 MPS. All Rights Reserved. 2 5 MP3421—5.5A, 600KHZ HIGH EFFICIENCY, SYNCHRONOUS, STEP-UP CONVERTER WITH OUTPUT DISCONNECT IN 2X2MM QFN PACKAGE TYPICAL CHARACTERISTICS (continued) VIN = VEN = 3.3V, VOUT = 5V, L = 1.5µH, TA = 25°C, unless otherwise noted. Linear-Charging Current Limit vs. Temperature MP3421 Rev. 1.0 11/13/2014 600 VIN=1.9V 800 VOUT=1.6V 400 200 VOUT=0V 0 -40 -20 0 20 40 60 80 100120140 LINEAR CHARGING LIMIT(mA) LINEAR CHARGING LIMIT(mA) 800 Linear-Charging Current Limit vs. Temperature VIN=3.3V 600 400 VOUT=1.6V 200 VOUT=0V 0 -40 -20 0 20 40 60 80 100120140 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2014 MPS. All Rights Reserved. 6 MP3421—5.5A, 600KHZ HIGH EFFICIENCY, SYNCHRONOUS, STEP-UP CONVERTER WITH OUTPUT DISCONNECT IN 2X2MM QFN PACKAGE TYPICAL PERFORMANCE CHARACTERISTICS VIN = 3.3V, VOUT = 5V, L=1.5uH, TA = 25°C, tested on standard EVB, unless otherwise noted. 100 98 96 94 92 90 88 86 84 0 0.5 1 1.5 2 2.5 2 2 1.5 1.5 1 1 0.5 0.5 0 0 -0.5 -0.5 -1 -1 -1.5 -1.5 -2 1.5 2 2.5 3 3.5 4 4.5 5 5.5 30 500 25 400 20 -2 0 0.5 1 1.5 2 2.5 VOUT/AC 100mV/div. 300 15 200 10 SW 2V/div. IL 2A/div. 100 5 0 0 VOUT/AC 100mV/div. 0.5 1 1.5 2 2.5 0 1.5 VOUT/AC 50mV/div. 2 2.5 3 3.5 4 4.5 5 VOUT 2V/div. VIN 2V/div. SW 2V/div. SW 2V/div. IL 2A/div. IL 5A/div. MP3421 Rev. 1.0 11/13/2014 SW 2V/div. IL 1A/div. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2014 MPS. All Rights Reserved. 7 MP3421—5.5A, 600KHZ HIGH EFFICIENCY, SYNCHRONOUS, STEP-UP CONVERTER WITH OUTPUT DISCONNECT IN 2X2MM QFN PACKAGE TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = 3.3V, VOUT = 5V, L=1.5uH, TA = 25°C, tested on standard EVB, unless otherwise noted. VOUT 2V/div. VOUT 2V/div. VOUT 2V/div. VIN 2V/div. EN 5V/div. EN 5V/div. SW 2V/div. SW 5V/div. SW 5V/div. IL 2A/div. IL 2A/div. IL 2A/div. VOUT 2V/div. VOUT 2V/div. VOUT/AC 200mV/div. VEN 5V/div. VSW 5V/div. IL 500mA/div. VOUT 2V/div. IL 5A/div. MP3421 Rev. 1.0 11/13/2014 VEN 5V/div. VSW 5V/div. IL 2A/div. ILOAD 500mA/div. VOUT 2V/div. IL 2A/div. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2014 MPS. All Rights Reserved. 8 MP3421—5.5A, 600KHZ HIGH EFFICIENCY, SYNCHRONOUS, STEP-UP CONVERTER WITH OUTPUT DISCONNECT IN 2X2MM QFN PACKAGE PIN FUNCTIONS Pin # Name Pin Function 1, 2, 13 PGND Power Ground. 3, 14 SW Power-Switch Output. SW is the internal NMOS switch and synchronous switch connection node . Connect the power inductor between SW and input power. Keep these PCB trace lengths as short and wide as possible to reduce EMI and voltage spikes. 4, 5, 6 OUT Output. OUT is the internal synchronous rectifier MOSFET drain. Bias is derived from OUT when VOUT is higher than VIN. PCB trace length from OUT to the output filter capacitor(s) should be as short and wide as possible. Due to the output disconnect feature, OUT is completely disconnected from IN when EN is low. 7 NC No Connect. Reserved for factory use only. Float or connect NC to GND in the application. 8 EN Enable Control Input. 9 IN Power-Supply Input. The startup bias is derived from IN. It must be locally bypassed. Once OUT exceeds IN, bias comes from OUT. Once started, operation is completely independent from IN. 10 INA 11 AGND 12 FB MP3421 Rev. 1.0 11/13/2014 Power-Supply Input (for factory use only). INA must be connected to IN in the application. Analog Signal Ground. Feedback Input to Error Amplifier. Connect resistor divider tap to FB. The output voltage can be adjusted from 2.5V to 5.5V www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2014 MPS. All Rights Reserved. 9 MP3421—5.5A, 600KHZ HIGH EFFICIENCY, SYNCHRONOUS, STEP-UP CONVERTER WITH OUTPUT DISCONNECT IN 2X2MM QFN PACKAGE FUNCTION DIAGRAM L1 Cin IN INA SCP/OVP SW VoutGood Body Vin Control A B C Startup PWM Control AGND 1.7V OUT Current Limit SYNC Drive Control R1 OSC 600KHz Slope Comp ∑ PGND Cp Rc Cout Cc RT PWM Comparator Vref EN Enable Control Undervoltage Lockout FB EA 0.8V REF Enable R2 Figure 1: Functional Block Diagram MP3421 Rev. 1.0 11/13/2014 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2014 MPS. All Rights Reserved. 10 MP3421—5.5A, 600KHZ HIGH EFFICIENCY, SYNCHRONOUS, STEP-UP CONVERTER WITH OUTPUT DISCONNECT IN 2X2MM QFN PACKAGE OPERATION The MP3421 is a 600kHz, synchronous step-up converter with true output disconnect offered in a compact QFN 2X2-14 lead package. It features fixed-frequency current mode PWM controls for excellent line and load regulation. Internal soft-start and loop compensation simplifies the design process and minimizes external components. The internal, RDS(ON) low MOSFETs, combined with frequency-stretching operation, allows the device to maintain high efficiency over a wide-load current range. Start-Up When the IC is enabled and IN voltage exceeds Vuvlo_in-R, the MP3421 starts up in the linear charge period. During this period, the PMOS rectifier turns on until the output capacitor is charged to 1.7V. The PMOS current is limited to 0.2A when VOUT is 0V to avoid an inrush current. While the output ramps, the PMOS current limit increases and ramps to 0.7A at 1.7V output. This circuit helps to limit the output current under short-circuit conditions. Once the output is charged to 1.7V, the linear charge period elapses and the MP3421 starts switching in normal closed-loop operation. In normal operation, with Vo lower than Vin +0.3V, the MP3421 operates in step-down mode with 4A typical peak-current limit. Also it works in boost mode when Vo is higher than Vin +0.3V with more than 5.5A current limit (see Table 1). Table 1: Work Mode during Startup VOUT<1.7V VOUT ≥1.7V & VOUT < VIN + 0.3V VOUT ≥1.7V & VOUT ≥ VIN + 0.3V Linear Charge Mode Down Mode Boost Mode In down mode (if HS-FET is on), the HS-FET gate is pulled to VIN and works with high impedance. In down mode, power loss is high and regulation is poor. Down mode is designed to work in startup and SCP conditions; do not set MP3421 in down mode for normal operation (unless the thermal temperature and regulation do not affect system performance). Once the output voltage exceeds the input voltage, the MP3421 powers its internal circuits from VOUT instead of Vin. Soft-Start (SS) The MP3421 provides soft-start by charging an internal capacitor with a current source. During the linear-charge period, the soft-start voltage rises, following the FB voltage. Once the linear charge period elapses and the voltage on the capacitor is charged, the reference voltage slowly ramps. The reference soft-start time is typically 2ms from 0V to 0.807V. The soft-start capacitor is discharged completely at output in the event of a commanded shutdown, thermal shutdown, or short circuit. Enable (EN) Operation is enabled when EN is switched high; it enters shutdown mode when EN is switched low. In shutdown mode, the regulator stops switching and all internal control circuitry is turned off; the load is isolated from the input. Power-Save Mode (PSM) The MP3421 automatically enters power-save mode (PSM) when the load decreases; it resumes PWM mode when the load increases. When the device goes into PSM, it lowers the switching frequency. This prevents switching and driver losses and switches to pulse-skip mode if the load continues to decrease. Error Amplifier (EA) The error amplifier (EA) is an internallycompensated amplifier. The EA compares the internal 0.807V reference voltage against VFB to generate an error signal. The output voltage of the MP3421 is adjusted by an external resistor divider. A voltage divider from VOUT to ground programs the output voltage via the FB from 2.5V to 5.5V using the equation: VOUT=0.807V x (1+R1/R2) Set the value of R1 and R2 to achieve lowquiescent current. R1 values larger than 600k MP3421 Rev. 1.0 11/13/2014 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2014 MPS. All Rights Reserved. 11 MP3421—5.5A, 600KHZ HIGH EFFICIENCY, SYNCHRONOUS, STEP-UP CONVERTER WITH OUTPUT DISCONNECT IN 2X2MM QFN PACKAGE are recommended transient balance. for good stability and Over-Load (OLP)and Short-Circuit (SCP) Protection Current Sensing Lossless-current sensing converts the NMOS switch current signal to voltage, which is summed with the internal slope compensation. The summed signal is compared to the error amplifier output to provide a peak-current control command for the PWM. The minimum peak-switch current limit is 5.5A. Internally, the switch-current signal is blanked for about 60ns to enhance noise rejection. If an overload or short circuit occurs, the output voltage drops. If VOUT drops below Vin +0.3 V, MP3421 converts to step-down mode. If VOUT drops below 1.7V, the device enters linear charge mode. If VOUT drops below 70% of the nominal output voltage, the MP3421 immediately shuts down and re-starts in a power-on cycle after 40μs. Output Disconnect The MP3421 has true output disconnect by eliminating body diode conduction from the internal PMOS rectifier. This allows VOUT to go to 0V during shutdown or isolate and maintain an external bias on VOUT. Also, it allows for inrush-current limit at startup, minimizing surge current from the input supply. To efficiently utilize output disconnect, eliminate (if necessary) the external Schottky diode connection between the switch and VOUT. If VOUT is higher than 7V, boost switching stops. This prevents overvoltage from damaging the internal power MOSFET. When the output drops below 7V, the device resumes switching automatically. MP3421 Rev. 1.0 11/13/2014 Over-Voltage Protection (OVP) Thermal Shutdown (TSD) The device contains an internal temperature monitor. The switches turn off if the die temperature exceeds 150°C. The device resumes normal operation below 130°C. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2014 MPS. All Rights Reserved. 12 MP3421—5.5A, 600KHZ HIGH EFFICIENCY, SYNCHRONOUS, STEP-UP CONVERTER WITH OUTPUT DISCONNECT IN 2X2MM QFN PACKAGE APPLICATION INFORMATION COMPONENT SELECTION L≥ Input Capacitor Selection Low ESR input capacitors reduce inputswitching noise and reduce the peak current drawn from the battery. Ceramic capacitors are recommended for input decoupling and should be located as close to the device as possible. A ceramic capacitor larger than 22μF is recommended to restrain the VIN ripple. Output Capacitor Selection To ensure stability over the full-operating range, the output capacitor requires a minimum capacitance value of 22μF at the programmed output voltage. A higher capacitance value may be required to lower both the output ripple and the transient ripple. Low ESR capacitors, such as X5R or X7R type ceramic capacitors are recommended. Supposing that ESR is zero, the minimum output capacitor to support the ripple in the PWM mode can be calculated by: CO ≥ IO × (VOUT(MAX) − VIN(MIN) ) fS × V OUT(MAX) ×ΔV Where, VOUT(MAX) = Maximum output voltage VIN(MIN) = Minimum Input voltage IO=Output current fS = Switching frequency ΔV= Acceptable output ripple A 1μF ceramic capacitor is recommended between the OUT and PGND. This reduces spikes on the SW node and improves EMI performance. Inductor Selection Due to the 600kHz switching frequency, the MP3421 utilizes small surface mount-chip inductors, Inductor values run between 1μH and 2.2μH, and they are suitable for most applications. Larger inductance values allow slightly greater output-current capability by reducing the inductor-ripple current. However, larger inductance values also increase component size. The minimum inductance value is given by: MP3421 Rev. 1.0 11/13/2014 VIN(MIN) × (VOUT(MAX) − VIN(MIN) ) VOUT(MAX) × ΔIL × fS (3) Where ΔIL=Acceptable inductor-current ripple. The inductor-current ripple is typically set at 30% to 40% of the maximum inductor current. The inductor should have low DCR (inductor current series resistance without saturating windings) to reduce the resistive power loss. The saturated current (ISAT) should be large enough to support the peak current. PCB Layout Considerations Proper PCB layout for high-frequency switching power supplies is critical. Poor layout results in weak performance, excessive EMI, resistive loss and system instability. The steps below ensure a good layout design: 1. The output capacitor must be placed as close as possible to the OUT, with minimal distance from PGND. A small decoupling capacitor should be parallel with the bulk output capacitor and placed as close as possible to the OUT. This is critical for reducing spikes on the SW and improving EMI performance. 2. The input capacitor and inductor should be as close as possible to the IN and SW. The trace between the inductor and the SW should be as wide and short as possible. 3. The feedback loop should be far from any noise sources, such as the SW. The feedback divider resistors should be as close as possible to the FB and AGND. 4. The ground return of the input/output capacitors should be tied as close as possible to the PGND with a large copper GND area. Vias around the GND are recommended to lower the die temperature. 5. INA must be connected to IN. NC can either float or be connected to GND. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2014 MPS. All Rights Reserved. 13 MP3421—5.5A, 600KHZ HIGH EFFICIENCY, SYNCHRONOUS, STEP-UP CONVERTER WITH OUTPUT DISCONNECT IN 2X2MM QFN PACKAGE Figure 2 shows recommended component placement for the MP3421. Top Layer SW L1 Bottom Layer Via VIN VOUT MP3421 OUT OUT OUT NC C1 SW SW IN PGND PGND PGND INA PGND C2A EN AGND R2 FB Design Example Table 2 shows a design example (using the application guidelines) for the following specifications: Table 2: Design Example VIN VOUT IOUT 2.8V-4.2V 5V 0A-2.1A C2B PGND Vias for heat sink R1 See Figure 3 for the detailed application schematic. The typical application circuit for VOUT = 5V is the basis for the typical performance waveforms. For details on additional device applications, please refer to the related evaluation board datasheets. Figure 2: Layout Recommendation MP3421 Rev. 1.0 11/13/2014 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2014 MPS. All Rights Reserved. 14 MP3421—5.5A, 600KHZ HIGH EFFICIENCY, SYNCHRONOUS, STEP-UP CONVERTER WITH OUTPUT DISCONNECT IN 2X2MM QFN PACKAGE TYPICAL APPLICATION CIRCUITS Figure 3: Typical Boost Application Circuit, VIN=2.8V to 4.2V, VOUT=5V, IOUT=0A-2.1A MP3421 Rev. 1.0 11/13/2014 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2014 MPS. All Rights Reserved. 15 MP3421—5.5A, 600KHZ HIGH EFFICIENCY, SYNCHRONOUS, STEP-UP CONVERTER WITH OUTPUT DISCONNECT IN 2X2MM QFN PACKAGE PACKAGE INFORMATION QFN-14 (2mmX2mm) 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. MP3421 Rev. 1.0 11/13/2014 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2014 MPS. All Rights Reserved. 16