max17502h evaluation kit evaluates: max17502h in tssop package component list general description the max17502h evaluation kit (ev kit) provides a prov - en design to evaluate the max17502h high-efficiency, high-voltage, synchronous step-down dc-dc converter in a tssop package. the ev kit uses the device to generate 2.5v at load currents up to 1a from a 4.5v to 60v input supply. the device features a forced-pwm control scheme that provides constant switching- frequency operation at all load and line conditions. features operates from a 4.5v to 60v input supply 2.5v output voltage 1a output current 300khz switching frequency enable/uvlo input resistor-programmable uvlo threshold open-drain reset output overcurrent and overtemperature protection proven pcb layout fully assembled and tested 19-6517; rev 0; 11/12 ordering information appears at end of data sheet. designation qty description c1 1 2.2f 10%, 100v x7r ceramic capacitor (1210) murata grm32er72a225k c2 1 1f 10%, 6.3v x7r ceramic capacitor (0603) murata grm188r70j105k c3 1 6800pf 10%, 25v x7r ceramic capacitor (0402) murata grm155r71e682k c4 1 47f 10%, 6.3v x7r ceramic capacitor (1210) murata grm32er70j476k c5 1 3300pf 10%, 50v x7r ceramic capacitor (0402) murata grm155r71h332k c6 0 not installed, ceramic capacitor (0402) c7 1 33f, 80v aluminum electrolytic (d = 8mm) panasonic eeefk1k330p c8 0 not installed, ceramic capacitor (1210) designation qty description c9 1 47pf 10%, 50v c0g ceramic capacitor (0402) murata grm1555c1h470j ju1 1 3-pin header l1 1 22h, 1.7a inductor (6mm x 6mm x 3.5mm) coilcraft lps6235-223ml r1 1 3.32m? 1% resistor (0402) r2 1 1m? 1% resistor (0402) r3 1 16.9k? 1% resistor (0402) r4 1 69.8k? 1% resistor (0402) r5 1 39.2k? 1% resistor (0402) r6 1 10k? 1% resistor (0402) r7 0 not installed, resistor (0402) tp1, tp2 0 not installed, test points u1 1 buck converter (14 tssop) maxim max17502haud+ 1 shunts 1 pcb: max17502hu evaluation kit downloaded from: http:///
maxim integrated 2 max17502h evaluation kit evaluates: max17502h in tssop package www.maximintegrated.com component suppliers note: indicate that you are using the max17502 when contacting these component suppliers. quick start recommended equipment max17502h ev kit 4.5v to 60v, 2a dc input power supply load capable of sinking 1a function generator 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. 1) set the power supply at a voltage between 4.5v and 60v. disable the power supply. 2) 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 1a load to the vout pcb pad and the negative terminal to the nearest pgnd pcb pad. 3) connect the dvm across the vout pcb pad and the nearest pgnd pcb pad. 4) verify that a shunt is installed across pins 1-2 on jumper ju1. 5) turn on the dc power supply. 6) enable the load. 7) verify that the dvm displays the expected voltage. to turn-on/off the part from en/uvlo, follow the steps below: 1) remove resistors r1 and r2 and the jumper connected across pins 1-2 on jumper ju1. 2) connect the power supply to the ev kit and turn on the power supply. set the power supply at a voltage between 4.5v and 60v. 3) connect the function generator output to the en/uvlo test loop. 4) the en/uvlo rising threshold is 1.24v and falling threshold is 1.11v, so make sure that the voltage high and voltage low levels of the function generator output are greater than 1.24v and less than 1.11v, respectively. 5) while powering down the ev kit, first disconnect the function generator output from the en/uvlo test loop and then turn off the dc power supply. detailed description the max17502h ev kit provides a proven design to evaluate the max17502h high-efficiency, high-voltage, synchronous step-down dc-dc converter in a tssop package. the ev kit generates 2.5v at load currents up to 1a from a 4.5v to 60v input supply. the ev kit features a 300khz fixed switching frequency for optimum efficiency and component size. the device features a forced-pwm control scheme that provides constant switching-frequen - cy operation at all load and line conditions. the ev kit includes an en/uvlo pcb pad to enable control of the converter output. an additional reset pcb pad is available for monitoring the converter output. the vcc pcb pad helps measure the internal ldo voltage. 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 c3, the external capacitor from ss to gnd. to adjust the soft-start time, determine c3 using the following formula: c3 = 5.55 x t ss where t ss is the required soft-start time in milliseconds and c3 is in nanofarads. supplier phone website coilcraft, inc. 847-639-6400 www.coilcraft.com murata electronics north america, inc. 770-436-1300 www.murata-northamerica.com panasonic corp. 800-344-2112 www.panasonic.com downloaded from: http:///
maxim integrated 3 max17502h evaluation kit evaluates: max17502h in tssop package www.maximintegrated.com regulator enable/undervoltage lockout level (en/uvlo) the device features an en/uvlo input. for normal operation, a shunt should be installed across pins 1-2 on jumper ju1. to disable the output, install a shunt across pins 2-3 on ju1 and the en/uvlo pin is pulled to gnd. see table 1 for ju1 settings. setting the undervoltage-lockout level the device offers an adjustable input undervoltage- lockout level. set the voltage at which the device turns on with a resistive voltage-divider connected from v in to gnd (see figure 1). connect the center node of the divider to en/uvlo. choose r1 to be 3.3m and then calculate r2 as follows: inu r1 1.218 r2 (v 1.218) = ? where v inu is the voltage at which the device is required to turn on. ensure that v inu is higher than 0.8 x v out . adjusting output voltage the device offers an adjustable output voltage. set the output voltage with a resistive voltage-divider connected from the positive terminal of the output capacitor (v out ) to gnd (see figure 6). connect the center node of the divider to fb/vo. to choose the values of r4 and r5, select the parallel combination of r4 and r5, r p to be less than 30k. once r p is selected, calculate r4 as follows: out rp v r4 0.9 = calculate r5 as follows: out r4 0.9 r5 (v 0.9) = ? ev kit performance report table 1. regulator enable (en/uvlo) jumper ju1 description *default position. figure 1. max17502h load and line regulationfigure 2. max17502h efficiency shunt position en/uvlo pin max17502_ output 1-2* connected to v in enabled not installed connected to center node of resistor-divider r1 and r2 enabled, uvlo level set through r1 and r2 divi der 2-3 connected to gnd disabled load and line regulation load current (ma) output voltage (v) 900 800 600 700 200 300 400 500 100 2.4875 2.4900 2.4925 2.4950 2.4975 2.50002.4850 0 1000 v in = 12v v in = 24v v in = 36v v in = 48v efficiency vs. load current load current (ma) efficiency (%) 900 800 600 700 300 400 500 200 70 75 80 85 9060 65 100 1000 v in = 12v v in = 24v v in = 36v v in = 48v downloaded from: http:///
maxim integrated 4 max17502h evaluation kit evaluates: max17502h in tssop package www.maximintegrated.com figure 3. max17502h full load bode plot (v in = 24v) figure 4. max17502h no load to 500ma load transient figure 5. max17502h 500ma to 1a load transient f cr = 33.7khz pm = 56.7 40s/div v out (ac) 50mv/div i out 200ma/div 40s/div v out (ac) 50mv/div i out 500ma/div downloaded from: http:///
maxim integrated 5 max17502h evaluation kit evaluates: max17502h in tssop package www.maximintegrated.com figure 6. max17502h ev kit schematic downloaded from: http:///
maxim integrated 6 max17502h evaluation kit evaluates: max17502h in tssop package www.maximintegrated.com figure 7. max17502h ev kit component placement guide component side figure 9. max17502hu ev kit pcb layoutsolder side figure 8. max17502h ev pcb layoutcomponent side figure 10. max17502hu ev kit pcb layouttop solder mask 1.0?? 1.0?? 1.0?? 1.0?? downloaded from: http:///
maxim integrated 7 max17502h evaluation kit evaluates: max17502h in tssop package www.maximintegrated.com figure 11. max17502hu ev kit pcb layoutbottom solder mask #denotes rohs compliant. ordering information part type max17502huevkit# ev kit 1.0?? downloaded from: http:///
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 speciications without n otice at any time. max17502h evaluation kit evaluates: max17502h in tssop package maxim integrated and the maxim integrated logo are trademarks of maxim integrated products, inc. ? 2012 maxim integrated products, inc. 8 revision history revision number revision date description pages changed 0 11/12 initial release for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim integrateds website at www.maximintegrated.com. downloaded from: http:///
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