MAX7544 5V Output Evaluation Kit Evaluates: MAX7544 in General Description The MAX7544 5V output evaluation kit (EV kit) provides a proven design to evaluate the MAX7544 high-voltage, high-efficiency, synchronous step-down DC-DC converter. The EV kit is preset for 5V output at load currents up to.5a and features a 500kHz switching frequency for optimum efficiency and component size. The EV kit features adjustable input undervoltage lockout, adjustable soft-start, open-drain RESET signal, and external frequency synchronization. Ordering Information appears at end of data sheet. Component List DESIGNATION QTY DESCRIPTION C, C8 C C C4, C9 C5 C6 0 C7 JU JU -pin headers.µf ±0%, 50V X7R ceramic capacitors (0) TDK C5X7RH5K.µF ±0%, 0V X7R ceramic capacitor (060) Murata GRM88R7A5K 000pF ±0%, 6V X7R ceramic capacitor (040) Murata GRM55R7CK µf ±0%, 0V X7R ceramic capacitors (0) Murata GRMER7A6K 0.µF ±0%, 6V X7R ceramic capacitor (040) Murata GRM55R7C04K Not installed, ceramic capacitor (040) 47µF, 50V aluminum electrolytic capacitor (D = 0mm) Panasonic EEEFKH470XP Features Operates from a 7.5V to 4V Input Supply 5V Output Voltage Up to.5a Output Current 500kHz Switching Frequency Enable/UVLO Input, Resistor-Programmable UVLO Threshold Adjustable Soft-Start Time MODE Pin to Select Among PWM, PFM, or DCM Modes Open-Drain RESET Output External Frequency Synchronization Overcurrent and Overtemperature Protection Proven PCB Layout Fully Assembled and Tested DESIGNATION QTY DESCRIPTION L *EP = Exposed pad. 0µH, 5.5A inductor TDK SLF575T-00M5R4-H Taiyo Yuden NS065T00MNA R.MΩ ±% resistor (040) R 604kΩ ±% resistor (040) R 00kΩ ±% resistor (040) R4.kΩ ±% resistor (040) R5 0 Not installed, resistor (040) R6 0kΩ ±% resistor (040) TP, TP Test pads U Buck converter (0 TQFN-EP*) Maxim MAX7544ATP+ Shunts (JU JU) PCB: MAX7544 5V OUTPUT EVKIT Note: C7, R, and R are optional components; R and R are not needed if the EN/UVLO pin is permanently connected to VIN. The electrolytic capacitor (C7) is required only when the VIN power supply is situated far from the MAX7544-based circuit. When R5 is open, the device switches at 500kHz switching frequency. The SLF575 inductor has been used to prepare the EV kit test report. 9-750; Rev 0; 9/4
MAX7544 5V Output Evaluation Kit Evaluates: MAX7544 in Component Suppliers SUPPLIER PHONE WEBSITE Murata Americas 800-4-6574 www.murataamericas.com Panasonic Corp. 800-44- www.panasonic.com Taiyo Yuden 800-48-496 www.t-yuden.com TDK Corporation 847-699-99 www.tdk.com Note: Indicate that you are using the MAX7544 when contacting these component suppliers. Quick Start Recommended Equipment MAX7544 5V output EV kit 7.5V to 4V, 7A DC input power supply Load capable of sinking.5a Digital voltmeter (DVM) Procedure The EV kit is fully assembled and tested. Follow the steps below to verify the board operation. Caution: Do not turn on power supply until all connections are completed. ) Set the power supply at a voltage between 7.5V and 4V. 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 the.5a load to the VOUT PCB pad and the negative terminal to the nearest PGND PCB pad. ) Connect the DVM across the VOUT PCB pad and the nearest PGND PCB pad. 4) Verify that shunts are installed across pins - on jumper JU and pins - on jumper JU (see Tables and for details). 5) Select the shunt position on jumper JU according to the intended mode of operation (see Table for details). 6) Turn on the DC power supply. 7) Enable the load. 8) Verify that the DVM displays 5V. Detailed Description The MAX7544 5V output EV kit provides a proven design to evaluate the MAX7544 high-voltage, highefficiency, synchronous step-down DC-DC converter. The EV kit is preset for 5V output from 7.5V to 4V input at load currents up to.5a and features a 500kHz switching frequency for optimum efficiency and component size. The EV kit includes an EN/UVLO PCB pad and jumper JU to enable the output at a desired input voltage. The SYNC PCB pad and jumper JU allow an external clock to synchronize the device. Jumper JU allows the selection of a particular mode of operation based on light-load performance requirements. An additional RESET PCB pad is available for monitoring whether the converter output is in regulation. Soft-Start Input (SS) The device utilizes an adjustable soft-start function to limit inrush current during startup. The soft-start time is adjusted by the value of C, the external capacitor from SS to GND. The selected output capacitance (C SEL ) and the output voltage (V OUT ) determine the minimum value of C, as shown by the following equation: C 8 x 0-6 x C SEL x V OUT The soft-start time (t SS ) is related to C by the following equation: t SS = C/(5.55 x 0-6) For example, to program a.ms soft-start time, C should be nf. Maxim Integrated
MAX7544 5V Output Evaluation Kit Evaluates: MAX7544 in Regulator Enable/Undervoltage-Lockout Level (EN/UVLO) The device offers an adjustable input undervoltagelockout level. For normal operation, a shunt should be installed across pins - on jumper JU. To disable the output, install a shunt across pins - on JU and the EN/ UVLO pin is pulled to GND. See Table for JU settings. Set the voltage at which the device turns on with the resistive voltage-divider R/R connected from VIN_ to SGND. Connect the center node of the divider to EN/UVLO. Choose R to be.mω and then calculate R as follows: R.5 R = (V INU.5) where V INU is the voltage at which the device is required to turn on. MODE Selection (MODE) The device s MODE pin can be used to select among PWM, PFM, or DCM modes of operation. The logic state of the MODE pin is latched when VCC and EN/UVLO voltages exceed the respective UVLO rising thresholds and all internal voltages are ready to allow LX switching. State changes on the MODE pin are ignored during normal operation. Refer to the MAX7544 IC data sheet for more information on PWM, PFM, and DCM modes of operation. Table shows EV kit jumper settings that can be used to configure the desired mode of operation. Table. Regulator Enable (EN/UVLO) Description (JU) 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 R5. The minimum external clock high pulse width should be greater than 50ns and the minimum external clock low pulse width should be greater than 60ns. Table. MODE Description (JU) SHUNT POSITION Not installed* - - Table. SYNC Description (JU) SHUNT POSITION - -* MODE PIN Unconnected Connected to SGND Connected to VCC SYNC PIN Connected to test loop on PCB Connected to SGND MAX7544_ MODE PFM mode of operation PWM mode of operation DCM mode of operation MAX7544_ SYNC Frequency can be synchronized with an external clock SYNC feature unused SHUNT POSITION EN/UVLO PIN MAX7544_ 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 - Connected to SGND Disabled Maxim Integrated
MAX7544 5V Output Evaluation Kit Evaluates: MAX7544 in EV Kit Test Report 5.08 5V OUTPUT, PWM MODE, FIGURE CIRCUIT, LOAD AND LINE REGULATION figure 00 5V OUTPUT, PWM MODE, FIGURE CIRCUIT, EFFICIENCY VS. LOAD CURRENT figure 5.07 5.06 90 OUTPUT VOLTAGE (V) 5.05 5.04 5.0 5.0 5.0 5 V IN = V V IN = 6V V IN = 4V 4.99 MODE = SGND 4.98 0 500 000 500 000 500 000 500 LOAD CURRENT (ma) EFFICIENCY (%) 80 70 60 50 V IN = V V IN = 4V MODE = SGND 40 0 500 000 500 000 500 000 500 LOAD CURRENT (ma) V IN = 6V Figure. MAX7544 5V Output Load and Line Regulation (PWM Mode) Figure. MAX7544 5V Output Efficiency (PWM Mode) 5.5 5V OUTPUT, PFM MODE, FIGURE CIRCUIT, LOAD AND LINE REGULATION figure 00 5V OUTPUT, PFM MODE, FIGURE CIRCUIT, EFFICIENCY VS. LOAD CURRENT figure4 OUTPUT VOLTAGE (V) 5.4 5. 5. 5. 5 4.9 4.8 V IN = V V IN = 4V 4.7 V IN = 6V 4.6 MODE = OPEN 4.5 0 500 000 500 000 500 000 500 LOAD CURRENT (ma) EFFICIENCY (%) 90 80 70 60 50 40 V IN = V V IN = 4V MODE = OPEN 0 0 00 000 500 LOAD CURRENT (ma) V IN = 6V Figure. MAX7544 5V Output Load and Line Regulation (PFM Mode) Figure 4. MAX7544 5V Output Efficiency (PFM Mode) Maxim Integrated 4
MAX7544 5V Output Evaluation Kit Evaluates: MAX7544 in EV Kit Test Report (continued) EFFICIENCY (%) 00 90 80 70 60 50 40 5V OUTPUT, DCM MODE, FIGURE CIRCUIT, EFFICIENCY VS. LOAD CURRENT V IN = 4V V IN = V V IN = 6V figure5 MODE = V CC 0 0 00 000 LOAD CURRENT (ma) Figure 5. MAX7544 5V Output Efficiency (DCM Mode) Figure 6. MAX7544 5V Output Full Load Bode Plot (V IN = 4V) 5V OUTPUT, PWM MODE (LOAD CURRENT STEPPED FROM NO LOAD TO.75A) figure 7 V OUT (AC) 00mV/div I OUT MODE = SGND 40μs/div A/div Figure 7. MAX7544 5V Output, No Load to.75a Load Transient (PWM Mode) Maxim Integrated 5
MAX7544 5V Output Evaluation Kit Evaluates: MAX7544 in EV Kit Test Report (continued) 5V OUTPUT, PFM MODE (LOAD CURRENT STEPPED FROM 5mA TO.75A) figure 8 5V OUTPUT, DCM MODE (LOAD CURRENT STEPPED FROM 50mA TO.75A) figure 9 V OUT (AC) 00mV/div V OUT (AC) 00mV/div I OUT MODE = OPEN A/div I OUT MODE = V CC A/div ms/div 00μs/div Figure 8. MAX7544 5V Output, 5mA to.75a Load Transient (PFM Mode) Figure 9. MAX7544 5V Output, 50mA to.75a Load Transient (DCM Mode) 5V OUTPUT, PWM MODE (LOAD CURRENT STEPPED FROM.75A TO.5A) figure 0 V OUT (AC) 00mV/div I OUT A/div 40μs/div Figure 0. MAX7544 5V Output,.75A to.5a Load Transient Maxim Integrated 6
MAX7544 5V Output Evaluation Kit Evaluates: MAX7544 in VIN PGND + C7 47uF 50V C8.uF C.uF JU EN/UVLO R 604k % R.M % SYNC R5 OPEN MODE SGND EN/UVLO VCC EN/UVLO JU JU VCC C.uF C 000pF 6 SYNC MODE VCC SGND 7 SS 0 RT 8 CF 4 EN/UVLO 9 FB VIN U MAX7544 4 PGND 5 PGND VIN 6 PGND VIN EP BST LX LX LX RESET 0 9 8 7 5 C5 0.uF R6 0k % L 0uH VCC RESET TP C4 uf TP C9 uf VOUT PGND RESET C6 OPEN R 00k % RESET R4.k % Figure. MAX7544 5V Output EV Kit Schematic Maxim Integrated 7
4 5 4 5 0 6 0 9 6 7 8 9 8 7 8 8 7 9 6 7 0 9 5 4 6 0 5 4 MAX7544 5V Output Evaluation Kit Evaluates: MAX7544 in 6 5 8 7 9 4.0.0 Figure. MAX7544 5V Output EV Kit Component Placement Guide Component Side Figure 4. MAX7544 5V Output EV Kit PCB Layout Inner Layer 6 5 8 7 9 4.0.0 Figure. MAX7544 5V Output EV Kit Component Side PCB layout Figure 5. MAX7544 5V Output EV Kit PCB Layout Inner Layer Maxim Integrated 8
MAX7544 5V Output Evaluation Kit Evaluates: MAX7544 in 6 5 8 7 9 4.0.0 Figure 6. MAX7544 5V Output EV Kit PCB Layout Solder Side Figure 7. MAX7544 5V Output EV Kit Component Placement Guide Top Solder Mask.0 Figure 8. MAX7544 5V Output EV Kit Component Placement Guide Bottom Solder Mask Maxim Integrated 9
MAX7544 5V Output Evaluation Kit Evaluates: MAX7544 in Ordering Information PART MAX7544EVKITB# #Denotes RoHS compliant. TYPE EV Kit Maxim Integrated 0
MAX7544 5V Output Evaluation Kit Evaluates: MAX7544 in Revision History REVISION NUMBER REVISION DATE DESCRIPTION PAGES CHANGED 0 9/4 Initial release For pricing, delivery, and ordering information, please contact Maxim Direct at -888-69-464, 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. 04 Maxim Integrated Products, Inc.