Evaluates: MAX17521 in 3.3V and 5V Output-Voltage Application. MAX17521 Evaluation Kit. General Description. Quick Start. Features

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1 MAX75 Evaluation Kit Evaluates: MAX75 in 3.3V and 5V General Description The MAX75 evaluation kit (EV kit) provides a proven design to evaluate the MAX75 dual high-efficiency, high-voltage, synchronous step-down DC-DC converter. The EV kit generates 3.3V and 5V output voltages at load currents up to A from a 7V to 6V input supply. The EV kit features a switching-frequency selector pin and individual mode-of-operation selector pins, enable/undervoltage-lockout (EN/UVLO) pins, programmable soft-start pins, and open-drain RESET_ signals for each output. Features Operates from a 7V to 6V Input Supply Dual-Output Voltage: 3.3V and 5V Up to A Output Current Pin-Selectable Switching Frequency Enable/UVLO Input, Resistor-Programmable UVLO Threshold Mode-Selection Pin for Each Output to Select Between PWM and PFM Modes Adjustable Soft-Start Time for Each Output Open-Drain RESET_ Signals for Each Output External Frequency Synchronization Overcurrent and Overtemperature Protection Proven PCB Layout Fully Assembled and Tested Ordering Information appears at end of data sheet. Quick Start Recommended Equipment MAX75 EV kit 7V to 6V, A DC input power supply Two loads capable of sinking A Two digital voltmeters (DVM) Procedure The EV kit is fully assembled and tested. Follow the steps below to verify the board operation. Caution: Do not turn on the power supply until all connections are completed. ) Set the power supply at a voltage between 7V and 6V. Disable the power supply. ) Connect the positive terminal of the power supply to the VIN PCB pad and the negative terminal to the nearest PGND PCB pad. Connect the positive terminal of one of the A loads to the VOUT PCB pad and the negative terminal to the PGND PCB pad. Connect the positive terminal of the other A load to the VOUT PCB pad and the negative terminal to the PGND PCB pad. 3) Connect the DVMs across the VOUT PCB pad and the PGND PCB pad and across the VOUT PCB pad and the PGND PCB pad. 4) Verify that shunts are installed across pins - on jumpers J, J, and J3. 5) Select the shunt position on J5 and J6 depending on the intended mode of operation. 6) Turn on the DC power supply. 7) Enable the loads. 8) Verify that the DVMs display 3.3V and 5V ; Rev ; 7/7

2 MAX75 Evaluation Kit Evaluates: MAX75 in 3.3V and 5V Detailed Description The MAX75 EV kit provides a proven design to evaluate the MAX75 high-efficiency, high-voltage, dual synchronous step-down DC-DC converter. The EV kit generates 3.3V and 5V, at load currents up to A, from a 7V to 6V input supply. The EV kit features a switching-frequency selector pin and individual mode-of-operation selector pins, enable/ undervoltage-lockout (EN/UVLO) pins, programmable soft-start pins, and open-drain RESET signals for each output. Soft-Start Input (SS) The device implements adjustable soft-start operation to reduce inrush current. Capacitors connected from the SS pins to programs the soft-start time for the corresponding output voltage. The selected output capacitance (C SEL ) and the output voltage (V OUT ) determine the minimum required soft-start capacitor as follows: C SS 56 x -6 x C SEL x V OUT The soft-start time (t SS ) is related to the capacitor connected at SS (C SS ) by the following equation: t SS = C SS /(5.55 x -6) For example, to program a ms soft-start time, a 5.6nF capacitor should be connected from the SS pin to. Table. Regulator Enable (EN/UVLO) Description (J) SHUNT POSITION EN/UVLO PIN MAX75_ OUTPUT -* Connected to VIN Enabled Not installed Connected to the center node of resistor-divider R3 and R4 Enabled, UVLO level set through the R3 and R4 resistors -3 Connected to Disabled Regulator Enable/Undervoltage-Lockout Level (EN/UVLO, EN/UVLO) The device offers an adjustable input undervoltagelockout level for each output. Set the voltage at which each converter turns on with a resistive voltage-divider connected from VIN to (viewable here). Connect the center node of the divider to EN/UVLO pin. Choose R TOP to be 3.3MΩ, and then calculate R BOTTOM as: RTOP.8 RBOTTOM = VINU.8 Where V INU is the input voltage at which a particular converter is required to turn on. Install a shunt across pins - on J and J to enable the EV kit s outputs. See Table and Table for proper jumper settings. Table. Regulator Enable (EN/UVLO) Description (J) SHUNT POSITION EN/UVLO PIN MAX75_ OUTPUT -* Connected to VIN Enabled Not installed Connected to the center node of resistor-divider R and R Enabled, UVLO level set through the R and R resistors -3 Connected to Disabled Maxim Integrated

3 MAX75 Evaluation Kit Evaluates: MAX75 in 3.3V and 5V Mode Selection (MODE, MODE) The device s MODE_ pins can be used to select between the PWM and PFM modes of operation. Refer to the MAX75 IC data sheet for more information on the PWM and PFM modes of operation. Table 3 and Table 4 show EV kit jumper settings that can be used to configure the desired mode of operation. Switching-Frequency Selection (FSEL) The device s FSEL pin can be used to select between 56kHz and 3kHz switching frequency. The EV kit is designed to operate at 56kHz switching frequency. If intended to operate at 3kHz, the values of the inductors, input and output capacitors, and the compensation components should be modified according to formulae provided in the MAX75 IC data sheet. Table 5 shows EV kit jumper settings that can be used to configure the switching frequency. Table 3. MODE Description (J6) SHUNT POSITION MODE PIN MAX75_ MODE Not installed* - Unconnected Connected to PFM mode of operation PWM mode of operation External Clock Synchronization (SYNC) The internal oscillator of the device can be synchronized to an external clock signal on the SYNC pin. The external synchronization clock frequency must be between.f SW and.4f SW, where f SW is the frequency of operation set by the FSEL pin. See Table 6 for jumper settings. Table 5. FSEL Description (J4) SHUNT POSITION FSEL PIN Switching Frequency Not installed* Unconnected 56kHz - Table 6. SYNC Description (J7) Connected to 3kHz SHUNT POSITION FSEL PIN SYNC - -3* Connected to test loop on PCB Connected to Frequency can be synchronized with an external clock SYNC feature unused Table 4. MODE Description (J5) SHUNT POSITION MODE PIN MAX75_ MODE Not installed* - Unconnected Connected to PFM mode of operation PWM mode of operation Maxim Integrated 3

4 MAX75 Evaluation Kit Evaluates: MAX75 in 3.3V and 5V EV Kit Performance Report (4V input voltage, unless otherwise noted.) EFFICIENCY (%) V OUTPUT, EFFICIENCY vs. LOAD CURRENT PFM MODE PWM MODE V IN = 4V, FSEL = OPEN LOAD CURRENT (ma) TOC EFFICIENCY (%) V OUTPUT, EFFICIENCY vs. LOAD CURRENT PFM MODE V IN = 4V, FSEL = OPEN LOAD CURRENT (ma) PWM MODE TOC OUTPUT VOLTAGE (V) 5V OUTPUT, LOAD REGULATION 5.5 V IN = 4V, FSEL = OPEN 5. PFM MODE PWM MODE LOAD CURRENT (ma) TOC3 OUTPUT VOLTAGE (V) V OUTPUT, LOAD REGULATION 3.43 V IN = 4V, FSEL = OPEN 3.4 PFM MODE PWM MODE LOAD CURRENT (ma) TOC4 5V OUTPUT, PWM MODE, FROM.5A TO A) TOC5 5V OUTPUT, PWM MODE, FROM TO.5A) TOC6 V OUT mv/div V OUT mv/div I OUT 5mA/div I OUT ma/div μs/div μs/div Maxim Integrated 4

5 MAX75 Evaluation Kit Evaluates: MAX75 in 3.3V and 5V EV Kit Performance Report (continued) (4V input voltage, unless otherwise noted.) 5V OUTPUT, PFM MODE, FROM 5mA TO 5mA) TOC7 3.3V OUTPUT, PWM MODE, FROM.5A TO A) TOC8 V OUT mv/div V OUT mv/div I OUT 5mA/div I OUT ma/div ms/div μs/div 3.3V OUTPUT, PWM MODE, FROM TO.5A) TOC9 3.3V OUTPUT, PFM MODE, FROM 5mA TO.5A) TOC V OUT 5mV/div V OUT mv/div I OUT ma/div I OUT ma/div μs/div ms/div 3 BODE PLOT (5V OUTPUT, A LOAD) toc 3 BODE PLOT (3.3V OUTPUT, A LOAD) toc PHASE PHASE GAIN 5 5 GAIN (db) PHASE ( ) GAIN (db) GAIN PHASE (º) V OUT = 5V f CR = 5kHz, PHASE MARGIN = V OUT = 3.3V f CR = 5KHz, PHASE MARGIN = FREQUENCY(Hz) 4 FREQUENCY(Hz) 5 Maxim Integrated 5

6 MAX75 Evaluation Kit Evaluates: MAX75 in 3.3V and 5V MAX75 EV Kit Bill of Materials Designator Value Description Part Number Manufacturer Quantity C, C.μF/X7R/V/ Input Capacitor GRM3ER7A5KA35L Murata C3 μf/x7r/v/ Output Capacitor GRM3DR7A6KA Murata C4 μf/x7r/v/ Output Capacitor GRM3ER7A6ME Murata C5, C6 μf/x7r/6.3v/63 VCC Bypass Capacitor GRM88R7J5KA Murata C7, C8 33pF/X7R/5V/4 Soft-start Capacitor GRM55R7H33KA Murata C9, C 7pF/X7R/5V/4 Compensation Capacitor GRM55R7H7KAJ Murata C 33pF Compensation Capacitor GRM555CH33JAD Murata C pf Compensation Capacitor GRM555CHJAD Murata L μh Inductor XAL55-3 Coilcraft L 5μH Inductor XAL44-53 Coilcraft R 8.5kΩ±%, 4 FB divider Resistor Vishay Dale R 8.kΩ±%, 4 FB divider Resistor Vishay Dale R3, R 3.3MΩ±%, 63 EN divider Resistor Vishay Dale R4 75kΩ±%, 63 EN divider Resistor Vishay Dale R5 5.8kΩ±%, 4 Compensation Resistor Vishay Dale R6, R7 kω±%, 4 RESET\ pull-up Resistor Vishay Dale R8.kΩ±%, 4 Compensation Resistor Vishay Dale R9 54.9kΩ±%, 4 FB divider Resistor Vishay Dale R.5kΩ±%, 4 FB divider Resistor Vishay Dale R MΩ±%, 63 EN divider Resistor Vishay Dale U MAX75 DC-DC Converter MAX75ATG+ Maxim Component Suppliers SUPPLIER WEBSITE Coilcraft, Inc. Murata Americas Vishay Note: Indicate that you are using the MAX75 when contacting these component suppliers. Ordering Information PART MAX75EVKITA# #Denotes RoHS-compliant. TYPE EV kit Maxim Integrated 6

7 Maxim Integrated 7 Evaluates: MAX75 in 3.3V and 5V MAX75 Evaluation Kit MAX75 EV Kit Schematic K EN/UVLO VIN PGND 3.3M R RESETN J RESETN EN/UVLO M R 54.9K R9 RESETN R.5K 8 PF C9 7PF 8.5K R 8.K R FB R8 R5 3 J7 3 3 J SYNC C C C C8 C7 C6 C5 C4 C3 C R7 R6 RESETN EN/UVLO PGND VIN PGND VOUT C R4 R3 L J3 J6 J5 EN/UVLO PGND4 VIN PGND3 VOUT L J U 33PF 33PF UF UF.UF.UF.UF 5UH UH 3.3M.UF 75K 7PF VCC PGND FB FB EN/UVLO PGND RESETN PGND VCC VIN VOUT VOUT VOUT VIN FB PGND VOUT PGND VCC VIN EN/UVLO VCC 33PF 5.8K K.K RESETN MAX75 EP LX MODE SYNC MODE LX PGND VIN EN/UVLO VCC FB SS COMP RESET FREQ RESET COMP SS FB VCC EN/UVLO VIN PGND

8 MAX75 Evaluation Kit Evaluates: MAX75 in 3.3V and 5V MAX75 EV Kit PCB Layout PCB Component Placement Guide: Component Side PCB Layout: Component Side PCB Layout: Inner Layer PCB Layout: Inner Layer Maxim Integrated 8

9 MAX75 Evaluation Kit Evaluates: MAX75 in 3.3V and 5V MAX75 EV Kit PCB Layout (continued) PCB Layout: Solder Side PCB Layout: Solder Mask PCB Layout: Component Placement Guide: Bottom Solder Mask Maxim Integrated 9

10 MAX75 Evaluation Kit Evaluates: MAX75 in 3.3V and 5V Revision History REVISION NUMBER REVISION DATE DESCRIPTION PAGES CHANGED 6/5 Initial release 7/7 Corrected symbols in equations in the Soft-Start Input (SS) and Regulator Enable/Undervoltage-Lockout Level (EN/UVLO, EN/UVLO) sections. Updated part number in Ordering Information table to MAX75EVKITA#., 6 For pricing, delivery, and ordering information, please contact Maxim Direct at , or visit Maxim Integrated s website at. 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. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. 7 Maxim Integrated Products, Inc.