MAX20472ATCA/V+T

Click here to ask about the production status of specific part numbers. MAX20471, MAX20472, MAX20472B Low Voltage Synchronous Boost Converter General Description Benefits and Features The MAX20471, MAX20472, and MAX20472B are highefficiency low-voltage DC-DC converters that boost a 3.0V to 4.0V input supply to between 3.8V and 5.25V (factoryconfigurable) at 500mA or 1A. The boost converters achieve ±1.5% output error over load, line, and temperature range. ● Multiple Functions for Small Size • Synchronous Boost Converter • 3.8V to 5.25V Factory-Preset Output in 50mV Steps • 500mA and 1A Options • 3V to 4V Operating Supply Voltage • True Output Shutdown • 2.2MHz Operation for the MAX20471, MAX20472 • 2.0MHz Operation for the MAX20472B • Open-Drain Reset Output Pin (RESET) • Spread-Spectrum Enable Pin (SSEN) The devices feature a 2.2MHz (2.0MHz for MAX20472B) fixed-frequency PWM mode for better noise immunity and load-transient response, and a pulse-frequency modulation mode (skip) for increased efficiency during light-load operation. The 2.2MHz/2.0MHz frequency operation allows for the use of all ceramic capacitors and minimizes external components. The programmable spread-spectrum frequency modulation minimizes radiated electromagnetic emissions. Integrated low-RDSON switches improve efficiency at heavy loads and make the layout a much simpler task with respect to discrete solutions. Other features include true shutdown, soft-start, overcurrent, and overtemperature protections. Applications ● Automotive Point of Load ● Automotive CAN Transceivers ● High-Precision • ±1.5% Output Voltage Accuracy • 93 ±2% UV Monitoring • 107 ±2% OV Monitoring • Good Load-Transient Performance ● Robust for the Automotive Environment • Current-Mode, Forced-PWM and SKIP Operation • Overtemperature and Short-Circuit Protection • 12-Pin (3mm x 3mm) TDFN • 12-Pin (3mm x 3mm) SWTDFN • 8-Pin (0.150") SOIC (MAX20471 Only) • -40°C to +125°C Automotive Temperature Range Ordering Information appears at end of data sheet. Simplified Block Diagram 3.3V 2.2µF 1µH LX 3.3V 5V AV OUT 1µF 22µF GND EN MAX20471 MAX20472/B PGND SYNC 50KΩ SSEN RESET 19-100163; Rev 13; 9/21 MAX20471, MAX20472, MAX20472B Low Voltage Synchronous Boost Converter TABLE OF CONTENTS General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Benefits and Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Simplified Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 12 TDFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 12 SWTDFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 8 SOIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Pin Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 MAX20471/MAX20472/MAX20472B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 MAX20471 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Functional Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Diagram 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Enable Input (EN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 RESET Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Internal Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Synchronization (SYNC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Soft-Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Current-Limit/Short-Circuit Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 PWM/SKIP Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Overtemperature Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Boost Converter Short Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Startup into Short . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Short or Overload after Soft-Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Input Capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Inductor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Boost Output Capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 PCB Layout Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Typical Application Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Circuit 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 www.maximintegrated.com Maxim Integrated | 2 MAX20471, MAX20472, MAX20472B Low Voltage Synchronous Boost Converter Absolute Maximum Ratings EN, SYNC to GND...................................................... -0.3V to 6V AV to GND .................................................................. -0.3V to 6V RESET to GND........................................................... -0.3V to 6V OUT to PGND............................................................. -0.3V to 6V SSEN to GND ..................................................-0.3V to VAV+0.3V LX to PGND (Note 1) .................................... -0.3V to VOUT+0.3V GND to PGND ......................................................... -0.3V to 0.3V Maximum Continuous RMS Current ...................................... 2.5A Output Short-Circuit Duration ..................................... Continuous Continuous Power Dissipation (Note 2) 12-Pin TDFN-EP (derate 24.4 mW/°C > 70°C) ...........1951mW 12-Pin SWTDFN-EP (derate 24.4 mW/°C > 70°C) .....1951mW 8-Pin SOIC (derate 7.8mW/ºC > +70ºC) .......................623mW Operating Temperature Range .............................-40°C to 125°C Junction Temperature ....................................................... +150°C Storage Temperature Range ..............................-65°C to +150°C Soldering Temperature (reflow) ........................................ +300°C Note 1: Self-protected from transient voltages exceeding these limits in circuit under normal operation. Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Package Information 12 TDFN Package Code TD1233+2C Outline Number 21-0664 Land Pattern Number 90-0397 Thermal Resistance, Four-Layer Board: Junction to Ambient (θJA) 41°C/W Junction to Case (θJC) 8.5°C/W 12 SWTDFN Package Code TD1233Y+2C Outline Number 21-100176 Land Pattern Number 90-100072 Thermal Resistance, Four-Layer Board: Junction to Ambient (θJA) 41°C/W Junction to Case (θJC) 8.5°C/W 8 SOIC Package Code S8+2C Outline Number 21-0041 Land Pattern Number 90-0096 Thermal Resistance, Four-Layer Board: Junction to Ambient (θJA) 128.4°C/W Junction to Case (θJC) 36°C/W For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial. www.maximintegrated.com Maxim Integrated | 3 MAX20471, MAX20472, MAX20472B Low Voltage Synchronous Boost Converter Electrical Characteristics (VAV = 3.3V, EN = 3.3V, TA = TJ = -40°C to +125°C, unless otherwise noted., Typical values are at TA = +25°C under normal conditions unless otherwise noted. (Note 3)) PARAMETER Supply Voltage Range UVLO SYMBOL VIN CONDITIONS (Note 4) VUVLOR Rising VUVLOF Falling Shutdown Supply Current ISD EN = LOW Supply Current IIN EN = high, IOUT = 0mA, SYNC low PWM Switching Frequency fSW Spread Spectrum SS Internally Generated Internally Generated, MAX20472B MIN TYP 3 2.48 2.55 MAX UNITS 4.25 V 2.9 2.475 0.1 2 130 µA µA 2 2.2 2.4 1.88 2.0 2.12 SSEN high V ±3 MHz % OUT Voltage Accuracy VOUT ILOAD = 0A to IMAX, 3V ≤ VAV ≤ 4.25V pMOS On-Resistance RHS VAV = 3.3V, ILX = 0.18A nMOS On-Resistance RLS VAV = 3.3V, ILX = 0.18A nMOS Current-Limit Threshold ILIM1 MAX20471 1.4 1.8 4 ILIM2 MAX20472/MAX20472B 2.8 4.2 7 pMOS Turn Off Threshold -1.5 +1.5 150 100 IZX VAV = 6V, LX = PGND or OUT, TA = 25°C % mΩ mΩ A 50 mA 0.1 μA LX Leakage Current ILXLKG Maximum Duty Cycle DCMAX OUT Discharge Resistance RDISCH VEN = 0V (connected to OUT) 300 Ω SKIP Threshold THSKIP Percentage of nMOS current-limit threshold (MAX20471/MAX20472 only) 15 % Soft-Start Time tSS 1.9 ms 165 °C 15 °C 90 % THERMAL OVERLOAD Thermal Shutdown Temperature TSHDN Hysteresis THYST TJ rising RESET OV Threshold OVACC Rising, % of nominal output 105 107 109 % UV Threshold UVACC Falling, % of nominal output 91 93 95 % tHOLD1 Option 1 (default) 0.5 tHOLD2 Option 2 3.7 tHOLD3 Option 3 7.4 14.8 Active Hold Period tHOLD4 Option 4 Delay Filter tUVDEL 10% below/above threshold Output-High Leakage Current IRLKG TA = 25°C Output Low Level VROL Sinking -2mA, 3V ≤ VAV ≤ 4.25V www.maximintegrated.com ms 10 -0.5 0.1 µs +0.5 μA 0.2 V Maxim Integrated | 4 MAX20471, MAX20472, MAX20472B Low Voltage Synchronous Boost Converter Electrical Characteristics (continued) (VAV = 3.3V, EN = 3.3V, TA = TJ = -40°C to +125°C, unless otherwise noted., Typical values are at TA = +25°C under normal conditions unless otherwise noted. (Note 3)) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS ENABLE AND SYNC INPUTS Input High Level VIH Input Low Level VIL Input Hysteresis VHYST EN Pulldown Current IENPD SYNC Input Pulldown RSYNCPD SYNC Input Frequency Range fSYNC 1.5 V 0.5 V 2 µA 0.1 VAV = 3.3V 0.5 EN high 1 V 100 1.7 kΩ 2.6 MHz Note 3: All units are 100% production tested at +25˚C. All temperature limits are guaranteed by design and characterization. Note 4: FPWM operation is only guaranteed up to 4.0V supply voltage. Supply voltages higher than 4.0V will exhibit skip mode behavior even with SYNC = HIGH for FPWM operation. www.maximintegrated.com Maxim Integrated | 5 MAX20471, MAX20472, MAX20472B Low Voltage Synchronous Boost Converter Typical Operating Characteristics (AVVDD = +3.3V, VDDIO = +1.8V, VREFP - VREFN = VREF = 2.5V; No Line-Frequency Rejection, Continuous-Conversion Mode, Internal Clock; TA = TMIN to TMAX unless otherwise noted.) www.maximintegrated.com Maxim Integrated | 6 MAX20471, MAX20472, MAX20472B Low Voltage Synchronous Boost Converter Pin Configurations EN AV GND GND RESET TOP VIEW SYNC MAX20471/MAX20472/MAX20472B 12 11 10 9 8 7 MAX20471 MAX MAX20472/B 20472/B 1 2 3 4 5 6 SSEN OUTS OUT LX LX PGND + TDFN-EP SWTDFN-EP 3mm x 3mm MAX20471 TOP VIEW EN 1 8 SYNC OUT 2 LX 3 6 GND PGND 4 5 RESET MAX20471 7 AV SOIC (0.150") Pin Description PIN MAX20471/ MAX20472/ MAX20472B MAX20471 1 — SSEN Spread Spectrum Enable. Connect to VAV to enable spread spectrum. 2 — OUTS Output Voltage Feedback Pin. Connect this pin to the output capacitor. NAME FUNCTION 3 2 OUT 4, 5 3 LX 6 4 PGND Power Ground. 7 5 RESET Open–Drain RESET Output. To obtain a logic signal, pull up RESET with an external resistor. 8 — 9 6 10 7 www.maximintegrated.com GND AV Output Voltage. Inductor Connection. Connect LX to the switched side of the inductor. Ground. Connect all ground pins to the EP. Analog Ground. Connect all ground pins to the EP. Analog Power Input Supply. Connect a 1μF ceramic capacitor from VAV to GND. Maxim Integrated | 7 MAX20471, MAX20472, MAX20472B Low Voltage Synchronous Boost Converter Pin Description (continued) PIN MAX20471/ MAX20472/ MAX20472B MAX20471 11 1 EN 12 8 SYNC SYNC Input. Connect SYNC to GND or leave unconnected to enable skip-mode operation under light loads. Connect SYNC to VAV or an external clock to enable fixed-frequency forced-PWM-mode operation. EP Exposed Pad. Connect the exposed pad to ground. Connecting the exposed pad to ground does not remove the requirement for proper ground connections to PGND. The exposed pad is attached with epoxy to the substrate of the die, making it an excellent path to remove heat from the IC. - — www.maximintegrated.com NAME FUNCTION Active-High Enable. Drive EN HIGH for normal operation. Maxim Integrated | 8 MAX20471, MAX20472, MAX20472B Low Voltage Synchronous Boost Converter Functional Diagrams Diagram 1 CS AMP SKIP COMP CLK OUT OUT RAMP GENERATOR ILIM COMP CONTROL LOGIC PGND LX PV LX PWM COMP VREF VREF SOFT-START GENERATOR PGND FPWM CLK EAMP PGND OUTS OUTS UV/OV ZX, NEG ILIM GND GND VREF SYNC SSEN CLK OTP TRIMBITS VAV OSC FPWM POK VOLTAGE REFERENCE VREF UVLO AV RESET EN MAIN CONTROL LOGIC www.maximintegrated.com PGND Maxim Integrated | 9 MAX20471, MAX20472, MAX20472B Low Voltage Synchronous Boost Converter Detailed Description The MAX20471, MAX20472, and MAX20472B are high-efficiency, low-voltage 500mA and 1A synchronous DC-DC boost converter ICs that boost the 3.0V to 4.0V input supply to a fixed output voltage between 3.8V and 5.25V. The boost converters have True Shutdown™, so the output voltage will be 0V when off. The ICs achieve ±1.5% output error over load, line, and temperature ranges. The ICs feature either a 2.2MHz (MAX20471/MAX20472) or a 2.0MHz (MAX20472B) fixed-frequency FPWM mode for better noise immunity and load-transient response, as well as pulse-frequency operation that allows the use of allceramic capacitors, thus minimizing external components. The programmable spread-spectrum frequency modulation minimizes radiated electromagnetic emissions. The spread modulation is factory set to pseudorandom. Integrated low RDS(ON) switches improve efficiency at heavy loads, which makes the layout a much simpler task with respect to discrete solutions. The ICs contain high-accuracy, factory-set OV/UV thresholds for each output mapped to the RESET pin. There are diagnostics on the RESET and OUT pins to guarantee high reliability and fail-safe operation. In light-load applications, a logic input (SYNC) allows the ICs to operate either in skip mode for reduced current consumption, or fixed-frequency FPWM mode to eliminate frequency variation and help minimize EMI. Enable Input (EN) The EN input activates the ICs’ channels from their low-power shutdown state. EN has an input threshold of 1.0V (typ), with hysteresis of 100mV (typ). When EN goes high, the associated output voltage ramps up with the programmed softstart time. RESET Output The device features individual open-drain, active-low reset outputs for each output that asserts low when the corresponding output voltage is outside of the UV/OV window. RESET remains asserted for a fixed timeout period after the output rises up to its regulated voltage. The fixed timeout period is selectable between 0.5ms, 3.7ms, 7.4ms, or 14.8ms (see the Selector Guide). To obtain a logic signal, place a resistor pullup between RESET pins to the system I/O voltage. Internal Oscillator The device has a spread-spectrum oscillator that varies the internal operating frequency up by ±3% relative to the internally generated typical operating frequency. This function does not apply to externally applied oscillation frequency. The spread frequency generated is pseudorandom with a repeat rate well below the audio band. Spread spectrum on MAX20471ASAA is enabled as an internal setting. Contact customer support for more details. Synchronization (SYNC) The ICs have an on-chip oscillator that provides a 2.2MHz/2.0MHz switching frequency. Depending on the condition of the SYNC pin for the MAX20471/MAX20472, two operation modes exist. If SYNC is unconnected or at GND and the load current is below the skip-mode current threshold, the ICs will operate in a highly efficient pulse-skipping mode. If the current is above the threshold, the ICs automatically change to FPWM mode. If SYNC is at VAV or has a frequency applied to it, the ICs will always operate in FPWM mode. The ICs can be switched during operation between FPWM or skip mode by pulling SYNC up to VAV or down to GND. For the MAX20472B, the SYNC pin operates differently. If the SYNC is unconnected or at GND for the MAX20472B the device will remain in pulse-skipping operation regardless of load current. If SYNC pin for the MAX20472B is at VAV or has a frequency applied to it, the device will always operate in FPWM mode. Soft-Start The IC includes a fixed soft-start of 1.9ms. Soft-start time limits start-up inrush current by forcing the output voltage to ramp up towards its regulation point. www.maximintegrated.com Maxim Integrated | 10 MAX20471, MAX20472, MAX20472B Low Voltage Synchronous Boost Converter Current-Limit/Short-Circuit Protection The device features current limit that protects the device against short-circuit and overload conditions at the output. In the event of a short-circuit or overload condition, the high-side MOSFET remains on until the inductor current reaches the high-side MOSFET’s current-limit threshold. The converter then turns on the low-side MOSFET to allow the inductor current to ramp down. Once the inductor current crosses below the low-side MOSFET current-limit threshold, the converter turns on the high-side MOSFET again. This cycle repeats until the short or overload condition is removed. PWM/SKIP Modes The device features an input (SYNC) that puts the converter either in SKIP mode for forced PWM mode of operation. See Pin Descriptions for mode detail. In PWM mode of operation, the converter switches at a constant frequency with variable on-time. In SKIP mode of operation, the converter’s switching frequency is load dependent until the output load reaches a certain threshold. At higher load current, the switching frequency does not change and the operating mode is similar to the PWM mode. SKIP mode helps improve efficiency in light-load applications by allowing the converter to turn on the high-side switch only when the output voltage falls below a set threshold. As such, the converter does not switch MOSFETs on and off as often as is the case in the PWM mode. Consequently, the gate charge and switching losses are much lower in SKIP mode. Overtemperature Protection Thermal overload protection limits the total power dissipation in the MAX20471, MAX20472, and MAX20472B. When the junction temperature exceeds 165°C (typ), an internal thermal sensor shuts down the internal bias regulator and the step-down controller, allowing the IC to cool. The thermal sensor turns on the IC again after the junction temperature cools by 15°C. Boost Converter Short Protection The boost has protection against startup into short and also protection against short/overload after startup. Startup into Short After the boost is enabled, the internal pMOS rectifier is configured as a 2A (typ) current source. This mode of operation is referred to as “charge mode” and is used to charge the output to within 600mV of the input. Under normal circumstances, charge mode is successful and the boost begins switching soft-start to 5.0V. If the output is shorted or overloaded, charge mode will be unable to charge the output to within 600mV of the input. If charge mode lasts for more than 1.9ms, the boost shuts off and automatically attempts restart after 120ms. This automatic restart is called “hiccup mode” and continues indefinitely. Disabling then reenabling the boost overrides the 120ms timer and retries immediately. Short or Overload after Soft-Start After soft-start is complete, the boost continues monitoring to ensure that the output is always greater than the 600mV input. If a short or overload condition pulls the output below the 600mV input, the boost stops switching and re-enters the charge-mode configuration. If the output continues to fall below 3.125V, independent of the input voltage, the boost shuts off and enters hiccup mode, as described above. www.maximintegrated.com Maxim Integrated | 11 MAX20471, MAX20472, MAX20472B Low Voltage Synchronous Boost Converter Applications Information Input Capacitor The input filter capacitor reduces peak currents drawn from the power source and reduces noise and voltage ripple on the input caused by the circuit’s switching. A 2.2µF X7R ceramic capacitor is recommended for the DC-DC input. A 1µF X7R ceramic capacitor is recommended for the VAV pin. Inductor Selection Use a 1µH inductor for MAX20472/MAX20471 and MAX20472B. For a ferrite core, the saturation current should be greater than the maximum current limit. For a soft-saturation core, the saturation current can be less than the maximum current limit as long as the inductance at the maximum current limit is greater than 50% of the nominal inductance. Boost Output Capacitor The MAX20471, MAX20472, and MAX20472B are designed to be stable with low-ESR ceramic capacitors. Other capacitor types are not recommended, as the ESR zero can affect stability of the device. The output-capacitor calculations below are guidelines based on nominal conditions. The phase margin must be measured on the final circuit to verify that proper stability is achieved. 55 µ sec COUT_MIN = V OUT 110 µ sec COUT_NOM = V OUT PCB Layout Guidelines When laying out the PCB, keep the DC-DC power components close together and the routes short to minimize loop area. The output capacitor, power inductor, and input capacitor should be placed close to the IC package. The output capacitor experiences the greatest amount of ripple current, and should be placed closest to the IC. The higher current-carrying traces, such as the input (LX) and OUT, should be wide. Vias should connect the exposed pad of the ICs to provide optimal ground and thermal dissipation connections. A large ground plane should be placed directly below the power traces. Typical Application Circuits Circuit 1 3.3V 2.2µF 1µH LX 3.3V 5V AV OUT 1µF 22µF GND EN MAX20471 MAX20472/B PGND SYNC 50KΩ SSEN RESET www.maximintegrated.com Maxim Integrated | 12 MAX20471, MAX20472, MAX20472B Low Voltage Synchronous Boost Converter Ordering Information TEMP RANGE PINPACKAGE VOUT (V) tHOLD (μs) INPUT CURRENT LIMIT (A) MAX20471ATCA/V+ -40°C to +125°C 12 TDFN-EP* 5 500 1.8 MAX20471ATCB/V+ -40°C to +125°C 12 TDFN-EP* 5.15 500 1.8 MAX20471ATCB/VY+ -40°C to +125°C 12 SWTDFNEP* 5.15 500 1.8 MAX20471ATCA/VY+ -40°C to +125°C 12 SWTDFNEP* 5 500 1.8 MAX20471ASAA/V+ -40°C to +125°C 8 SOIC 5 500 1.8 MAX20472ATCA/V+ -40°C to +125°C 12 TDFN-EP* 5 500 4.2 MAX20472ATCB/V+ -40°C to +125°C 12 TDFN-EP* 5.15 500 4.2 MAX20472ATCC/V+ -40°C to +125°C 12 TDFN-EP* 3.85 500 4.2 MAX20472ATCA/VY+ -40°C to +125°C 12 SWTDFNEP* 5 500 4.2 MAX20472BATCC/V+ -40°C to +125°C 12 TDFN-EP* 3.85 500 4.2 MAX20472ATCE/V+ -40°C to +125°C 12 TDFN-EP* 5 14800 4.2 PART NUMBER Note: For variants with different options, contact factory. /V Denotes an automotive qualified part. Y Denotes side-wettable. + Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel. *EP = Exposed pad. www.maximintegrated.com Maxim Integrated | 13 MAX20471, MAX20472, MAX20472B Low Voltage Synchronous Boost Converter Revision History REVISION NUMBER REVISION DATE 0 9/17 Initial Release — 1 1/18 Changed part in Ordering Information table from MAX20471ASA/V+** to MAX20471ASAA/V+** and removed future product status from MAX20472ATCA/V* 9 2 5/18 Updated Internal Oscillator section and added Boost Converter Short Protection, Startup into Short, and Short or Overload after Soft-Start sections 7, 8 3 6/18 Added MAX20472ATCB/V+** (future product) to Ordering Information table. 10 4 9/18 Removed all references to MAX20473 and 2A convertor operation; updated Pin Configuration; updated Functional Diagram; updated Inductor Selection and Output Capacitor sections; updated Typical Application Circuit; removed MAX20473ATCA/ V+** and future-part designation for MAX20471ATCB/V+ from the Ordering Information table 5 11/18 Removed future-part designation for MAX20472ATCB/V+ from the Ordering Information table 11 6 12/18 Updated Package Information table 2 7 3/19 Added information for SWTDFN package to Benefits and Features, Absolute Maximum Ratings, Package Information, Pin Configurations, and Ordering Information; added MAX20472ATCC/V+** to Ordering Information 8 6/19 Removed future-part designation from MAX20471ASAA/V+ in the Ordering Information table 11 9 8/19 Added notes to Ordering Information table 11 9.1 PAGES CHANGED DESCRIPTION Corrected Revision Date for Rev 9 in Revision History 1–11 1, 2, 6, 11 11 10 6/20 Added MAX20472B 1–14 11 8/20 Updated Package Information, Ordering Information 12 9/20 Updated Benefits and Features, Absolute Maximum Ratings, Electrical Characteristics, Pin Description, Detailed Description, and Applications Information; removed future-product notation from MAX20471ATCA/VY+T in Ordering Information 1, 3, 4, 5, 7, 8, 10, 12, 13 13 9/21 Updated Electrical Characteristics, Detailed Description, and Ordering Information 4, 5, 10, 13 3, 14 For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html. Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. © 2021 Maxim Integrated Products, Inc.