Click here for production status of specific part numbers. Evaluates: MAX20471 MAX20471 Evaluation Kit General Description Quick Start The MAX20471 evaluation kit demonstrates the perfor- Required Equipment mance of the MAX20471, which is part of the MAX20471 MAX20471 EV kit MAX20473 series of high-efficiency, low-voltage DC-DC 3.3V, 2A power supply converters. The converter ICs boost a 3.0V to 4.0V input supply to between 3.8V and 5.25V at up to 500mA. The 10, 25W resistor or 1A electronic load boost converters achieve 1.5% output error over load, Digital multimeter (DMM) line, and temperature range. Procedure The IC features a 2.2MHz fixed-frequency forced-PWM The EV kit is fully assembled and tested. Follow the steps (FPWM) mode for better noise immunity and load-transient below to verify board operation: response, and a pulse-frequency modulation mode (skip) for increased efficiency during light-load operation. The 1) Connect the 3.3V supply to the VSUP and GND PCB 2.2MHz frequency operation enables the use of all-ceramic pads. capacitors and minimizes external components. The pro- 2) Remove the EN jumper. grammable spread-spectrum-frequency modulation mini- 3) Activate the supply. Use the DMM to verify that the mizes radiated electromagnetic emissions. Integrated low voltage at the supply is 3.3V, the output is 0V, and R switches improve efficiency at heavy loads and DS(ON) the RESET pin voltage is 0V. make the layout a much simpler task with respect to dis- 4) Place a jumper across pins 1-2 on the EN header. crete solutions. Use the DMM to verify that the voltage at the output is 5.0V and the RESET pin is 3.3V. The regulator includes True Shutdown, soft-start, over- 5) Connect the load (either resistive or electronic) to current, and overtemperature protections. OUT and GND. 6) Use the DMM to verify output voltage is still 5.0V. Benefits and Features 3.0V to 4.0V Operating Supply Voltage 3.8V to 5.25V Fixed Output 500mA Output Version Populated Compatible with 1A and 2A Output Versions 2.2MHz Operation Ordering Information appears at end of data sheet. Feedback Injection Point-to-Test Stability Robust for the Automotive Environment Current Mode, Forced-PWM and Skip Operation Overtemperature and Short-Circuit Protection -40C to +125C Operating Range Proven PCB Layout Fully Assembled and Tested True Shutdown is a trademark of Maxim Integrated Products, Inc. 319-100106 Rev 0 11/17Evaluates: MAX20471 MAX20471 Evaluation Kit Spread Spectrum (SSEN) Detailed Description of Hardware The IC has the option to enable spread-spectrum switching The MAX20471 EV kit comes fully assembled and tested. to reduce EMI. Spread spectrum can be enabled by install- The IC populated on the EV kit determines the pack- ing a jumper between pins 1-2 on the SSEN header, or dis- age and the output current limit. Any of the ICs in the abled by installing a jumper between pins 2-3. With spread MAX204xx series of high-efficiency, low-voltage DC-DC spectrum enabled, the internal oscillator varies the internal converters can be tested on this EV kit. Changing the IC operating frequency by 3% relative to the internally gener- may also require changing the external components on ated 2.2MHz (typ) operating frequency. This function does the EV kit. Refer to the MAX20471MAX20473 IC data not apply to an externally applied oscillation frequency. The sheet for guidance on selecting the proper components. spread-spectrum frequency generated is pseudorandom, EV Kit Interface with a repeat rate well below the audio band. The VSUP and GND PCB pads provide power to the EV Fault Flag Signal (RESET) kit. Input capacitance is included to reduce peak currents The IC features an open-drain reset output for each drawn from the power source and reduces noise and volt- output that asserts low when the corresponding output age ripple on the input caused by the circuits switching. voltage is outside the undervoltage/overvoltage window. The regulator provides output power at the OUT and GND RESET remains asserted for a fixed timeout period after pins. Output capacitance is selected to ensure proper the output rises to its regulated voltage. The fixed timeout stability. period is 0.5ms by default, but can also be factory-set to The enable control input (EN) activates the IC channel 3.7ms, 7.4ms, or 14.9ms. To obtain a logic signal, place a from its low-power shutdown state. EN has an input pullup resistor between the RESET pin and VSUP. threshold of 1.0V (typ), with hysteresis of 80mV (typ). When an enable input goes high, the associated output PCB Layout Guidelines voltage ramps up with the programmed soft-start time. Proper PCB layout of the system is crucial to good perfor- The IC can be turned on either by installing a shunt/ mance. The loop area created by the DC-DC components jumper across pins 1-2 on the EN header, or by applying must be minimized as much as possible. Place the input a logic-high signal to the EN PCB pad. To turn off the IC, capacitor, power inductor, and output capacitor as close as remove the shunt on pins 1-2 and install a shunt across possible to the IC package. The output capacitor experi- pins 2-3 on the EN header, or apply a logic-low signal to ences the greatest amount of ripple current, so should the EN PCB pad. be placed closest to the IC. Increasing the loop area will increase EMI and switching jitter, but may also degrade Synchronization and Switching regulation and transient response. Optimal positioning and The IC has an on-chip oscillator that provides a 2.2MHz routing has been implemented on this EV kit. (typ) switching frequency. Depending on the condition of SYNC, two operation modes exist. If SYNC is unconnect- ed or at GND, the IC operates in a highly efficient pulse- skipping mode if the load current is below the skip-mode current threshold. If the current is above the threshold, Ordering Information the IC automatically changes to FPWM mode. If SYNC is PART TYPE at VSUP or has a frequency applied to it, the IC always MAX20471EVKIT EV Kit operates in FPWM mode. The IC can be switched during Denotes RoHS compliant. operation between FPWM and skip mode by switching SYNC. SYNC can be connected to VSUP by installing a shunt across pins 1-2 on the SYNC header, or connected to GND by installing a shunt across pins 2-3 on the SYNC header. An external square wave can be applied to the SYNC test point to cause the converter to switch at the applied frequency (refer to the MAX20471MAX20473 IC data sheet for limits). Maxim Integrated 2 www.maximintegrated.com