Evaluates: MAX17531 (TDFN) in MAX17531 5V Output 5V Output Voltage Applications Evaluation Kit (TDFN) Procedure General Description The EV kit is fully assembled and tested. Follow the steps The MAX17531 5V evaluation kit (EV kit) (TDFN) is a fully below to verify board operation. Caution: Do not turn on assembled and tested circuit board that demonstrates the the power supply until all connections are completed. performance of the MAX17531 42V, 50mA ultra-small, high-efficiency, synchronous step-down DC-DC converter 1) Verify that shunts are installed on jumpers JU1, JU2 in a 10-pin TDFN package. The EV kit operates over (EN/UVLO). a wide input voltage range of 6V to 42V and provides 2) Verify that jumper JU3 (MODE-PFM operation) is open. up to 50mA load current at 5V output. It draws only 3) Set the electronic load to constant-current mode, 26A supply current under no-load conditions (EN/UVLO 50mA, and disable the electronic load. connected to V ). The EV kit is programmed to switch at a IN 4) Connect the electronic loads positive terminal to the frequency of 300kHz. The device is simple to use and easily VOUT PCB pad. Connect the negative terminal to configurable with minimal external components. It the GND PCB pad. features cycle-by-cycle peak current-limit protection, undervoltage lockout, and thermal shutdown. 5) Connect the voltmeter across the VOUT and GND PCB pads. The EV kit comes installed with the MAX17531ATB+ in 6) Set the power-supply output to 24V. Disable the a 10-pin (3mm x 2mm) lead(Pb)-free/RoHS-compliant power supply. TDFN package. 7) Connect the power-supply output to the VIN PCB Features pad. Connect the supply ground to the GND PCB pad. 6V to 42V Input Voltage Range 8) Turn on the power supply. 5V Output, 50mA Continuous Current 9) Enable the electronic load and verify that output voltage 26A No-Load Supply Current is 5V with respect to GND. EN/UVLO for On/Off Control and Programmable 10) Vary the input voltage from 6V to 42V. Input Undervoltage Lockout 11) Vary the load current from 1mA to 50mA and verify Programmable Switching Frequency that output voltage is 5V with respect to GND. Internal or Programmable Soft-Start Note: While performing an output short-circuit test, it is PFM or Forced-PWM Mode of Operation possible for the ceramic output capacitor to oscillate with the wiring inductance between the capacitor and short- Open-Drain RESET Output circuited load, and thereby cause the absolute maximum Peak Current-Limit Protection rating of the V pin (-0.3V) to be exceeded. The OUT Thermal Shutdown resistor (R7) and the capacitor (C5) are included on this evaluation kit to protect against unintentional violation of Proven PCB Layout the above mentioned rating. In the actual system design, Fully Assembled and Tested parasitic board or wiring inductance should be minimized and the output-voltage waveform under short-circuit Quick Start operation should be verified to ensure that the absolute maximum rating of the V pin is not exceeded. Recommended Equipment OUT MAX17531 5V EV kit (TDFN) Ordering Information appears at end of data sheet. 42V adjustable, 0.5A DC power supply Electronic load up to 50mA Voltmeter 19-7709 Rev 0 7/15Evaluates: MAX17531 (TDFN) in MAX17531 5V Output Evaluation Kit (TDFN) 5V Output Voltage Applications RESET Output Detailed Description The EV kit provides a PCB pad to monitor the status of The MAX17531 5V EV kit (TDFN) is a fully assembled and the RESET output. RESET goes high when the output tested circuit board that demonstrates the performance voltage rises above 95% (typ) of its nominal regulated of the MAX17531 42V, 50mA ultra-small, high-efficiency, output voltage. RESET goes low when output voltage falls synchronous step-down DC-DC converter in a 10-pin below 92% (typ) of its nominal regulated voltage. TDFN package. The EV kit operates over a wide input voltage range of 6V to 42V and provides up to 50mA load PFM or Forced-PWM Mode (MODE) current at 5V output. It draws only 26A supply current The EV kit includes a jumper (JU3) to select the mode under no-load conditions (EN/UVLO connected to VIN). The of operation of the converter. Install a shunt across JU3 EV kit is programmed to switch at a frequency of 300kHz. before powering up the EV kit to enable the forced-PWM The device is simple to use and easily configurable with mini- operation. Keep JU3 open to enable the light-load PFM mal external components. It features cycle-by-cycle peak operation. See Table 2 for proper JU3 settings. current-limit protection, undervoltage lockout, and thermal shutdown. Soft-Start The EV kit includes an EN/UVLO PCB pad and jumpers The EV kit offers a fixed 5ms soft-start time. Connect JU1 and JU2 to enable control of the converter output. capacitor C4 to adjust the soft-start time (t ). The SS The MODE PCB pad and jumper JU3 are provided minimum soft-start time is related to the output for selecting the mode of operation of the converter. A capacitance (C ) and the output voltage (V ) by the OUT OUT RESET PCB pad is available for monitoring the RESET following equation. output. The RT/SYNC PCB pad can be used to synchro- t > 0.05 x C x V SS OUT OUT nize the EV kit switching frequency to an external clock where t is in milliseconds and C is in F. frequency. SS OUT Use the following equation to determine the soft-start Enable Control (JU1, JU2) capacitance value (C ): SS The EN/UVLO pin on the EV kit serves as an on/off control C = 6.25 x t SS SS while also allowing the user to program the input under- where t is in milliseconds and C is in nanofarads. voltage-lockout (UVLO) threshold. Jumpers JU1 and JU2 SS SS configure the EV kits output for turn-on/turn-off control. External Synchronization (RT/SYNC) See Table 1 for proper JU1, JU2 jumper configurations. The EV kit provides a PCB pad to synchronize the EV kit Additionally, resistors R1 and R2 are included to set the switching frequency to an external clock frequency. Refer UVLO to a desired turn-on voltage. Refer to the Setting to the External Synchronization section in the MAX17531 the Input Undervoltage-Lockout Level section in the IC data sheet for additional information on configuring the MAX17531 IC data sheet for additional information on external clock. setting the UVLO threshold voltage. Table 1. Enable Control (EN/UVLO) (JU1, JU2) SHUNT POSITION EN/UVLO PIN VOUT OUTPUT JU1 JU2 1-2 Open Connected to VIN Enabled Open 1-2 Connected to GND Disabled 1-2* 1-2 Connected to midpoint of R1, R2 resistor-divider Enabled at VIN 6V *Default position. Table 2. MODE Control (JU3) SHUNT POSITION MODE PIN MODE OF OPERATION 1-2 Connected to GND Forced PWM Open* Unconnected PFM *Default position. Maxim Integrated 2 www.maximintegrated.com