general description the max15026b evaluation kit (ev kit) is a fully assem-bled and tested pcb that contains all the components necessary to evaluate the performance of the max15026b 10a synchronous step-down controller. the max15026b ev kit requires a 5v to 16v power sup- ply that provides up to 4a for normal operation. the max15026b ev kit output is configured to 1.5v and delivers up to 10a output current. the controller switch- ing frequency is programmed to 600khz. the max15026b ev kit includes pcb pads to enable the cir- cuit and to monitor the power-good output. features ? 5v to 16v input range ? optional 4.5v to 5.5v input range for max15026b ic ? 1.5v at 10a output ? 600khz switching frequency ? enable input ? power-good output ? fully assembled and tested evaluates: max15026b max15026b evaluation kit ________________________________________________________________ maxim integrated products 1 19-4181; rev 0; 6/08 component list for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. ordering information designation qty description c1 1 330f 20%, 25v electrolytic capacitor (10mm x 10.2mm) panasonic eeefc1e331p c2 1 4.7f 10%, 25v x5r ceramic capacitor (0805) murata grm21br61e475k c3 1 1f 10%, 25v x5r ceramic capacitor (0603) murata grm188r61e105k c4 1 4.7f 10%, 6.3v x5r ceramic capacitor (0603) murata grm188r60j475k c5 1 2.2f 10%, 6.3v x5r ceramic capacitor (0603) murata grm188r60j225k c6 1 10f 10%, 25v x5r ceramic capacitor (1206) murata grm31cr61e106k c7 0 not installed, ceramic capacitor (1206) c8 1 0.47f 10%, 16v x7r ceramic capacitor (0603) murata grm188r71c474k c9 1 2700pf 5%, 50v c0g ceramic capacitor (0805) murata grm2165c1h272ja c10 1 470f 20%, 4v electrolytic capacitor (8mm x 10.5mm) sanyo 4ce470ex c11, c12 2 22f 10%, 6.3v x5r ceramic capacitors (1206) murata grm31cr60j226k designation qty description c13 1 68pf 5%, 50v c0g ceramic capacitor (0603) murata grm1885c1h680j c14 1 15pf 5%, 50v c0g ceramic capacitor (0603) murata grm1885ch150j c15 1 1500pf 10%, 50v c0g ceramic capacitor (0603) murata grm1885c1h152k c16 1 2200pf 5%, 50v c0g ceramic capacitor (0603) murata grm1885c1h222j c17 0 not installed, ceramic capacitor (0603) ju1 1 3-pin header ju2 1 2-pin header l1 1 1.4h, 22a inductor coilcraft mss1278-142ml n1 1 30v, 74a n-channel mosfet (so-8fl) on semiconductor ntmfs4837nt1g n2 1 30v, 104a n-channel mosfet (so- 8fl) on semiconductor ntmfs4835nt1g pgnd (2), vin, vout 4 uninsulated banana jacks tp1, tp2 2 pc mini red test points r1, r6, r8 0 not installed, resistors (0603) r2 1 200k 1% resistor (0603) r3 1 10 5% resistor (0603) r4 1 51k 5% resistor (0603) part type MAX15026BEVKIT+ ev kit + denotes lead-free and rohs compliant. downloaded from: http:///
evaluates: max15026b max15026b evaluation kit 2 _______________________________________________________________________________________ quick start required equipment before beginning, the following equipment is needed: max15026b ev kit adjustable 5v to 16v, 4a dc power supply electronic load capable of sinking 10a (e.g., hp6060b) two voltmeters procedure the max15026b ev kit is fully assembled and tested.follow the steps below to verify board operation. caution: do not turn on the power supply until all connections are completed. 1) install a shunt across pins 1-2 of jumper ju1 (vin input source for u1). 2) install a shunt at jumper ju2 (vout enabled). 3) connect a voltmeter to the vout and pgnd pads. 4) connect a voltmeter to the pgood and agnd pads. 5) connect a 10a electronic load to the vout and pgnd banana jack connectors. 6) connect a dc power supply to the vin and pgnd banana jack connectors and set the voltage to 12v. 7) enable the power supply. 8) enable the electronic load and set it to 10a. 9) verify that the voltmeters at vout and pgood are 1.5v and approx 5.2v, respectively. detailed description of hardware the max15026b ev kit is a fully assembled and testedpcb that contains all the components necessary to evaluate the performance of the max15026b 10a syn- chronous step-down controller. the circuit uses a max15026b step-down controller ic to implement a step-down synchronous dc-dc converter circuit. the max15026b ev kit is designed to operate from a single dc power supply that provides 5v to 16v and 4a of current. the max15026b controller can also be operat- ed using a separate 4.5v to 5.5v power source applied at the vcc and agnd pcb pads. when operating the max15026b ev kit using separate power-supply sources at the vin connector and vcc pcb pad, apply power at the vin and pgnd connectors first and then the vcc and agnd pcb pads. the max15026b ev kit converter is configured to 1.5v and provides up to 10a output current. the switching frequency is set to 600khz using resistor r14. the ev kit features pcb pads to evaluate the enable input sig- nal (en) and to monitor the power-good (pgood) and vcc output signals. component list (continued) designation qty description r5 1 2.2 5% resistor (0603) r7 1 1 1% resistor (1210) r9 1 11.8k 1% resistor (0603) r10 1 22.6k 1% resistor (0603) r11 1 5.9k 1% resistor (0603 r12 1 15.4k 1% resistor (0603) r13 1 10k 1% resistor (0603) r14 1 27k 1% resistor (0603) designation qty description r15 1 49.9 1% resistor (0805) u1 1 10a synchronous step-down controller (14 tdfn-ep*) maxim max15026betd+ (top mark: +adp) 2 shunts (ju1, ju2) 1 pcb: max15026b evaluation kit+ component suppliers supplier phone website coilcraft, inc. 847-639-6400 www.coilcraft.com murata electronics north america, inc. 770-436-1300 www.murata-northamerica.com on semiconductor 602-244-6600 www.onsemi.com panasonic corp. 800-344-2112 www.panasonic.com sanyo electric co., ltd. 619-661-6835 www.sanyodevice.com note: indicate that you are using the max15026b when contacting these component suppliers. * ep = exposed pad. downloaded from: http:///
converter input source banana jack connectors vin and pgnd are used asthe power source for the converter. the max15026b ev kit converter output performance is optimized over the 5v to 16v vin input voltage range and up to 10a output current. the max15026b ev kit can operate above the 16v maximum input-voltage range and at higher output currents; however, performance may be degraded due to the limitation of the components used in the circuit. max15026b ic bias input (ju1) the max15026b ev kit features an option to select thebias input for the max15026b ic controller when con- figuring the ev kit to operate with an input source less than 6v. jumper ju1 selects the input-voltage source for the max15026b ic controller. place a shunt across pins 1-2 to power the max15026b ic using the power source applied at the vin and pgnd banana jack con- nectors. place a shunt across pins 2-3 to power the max15026b ic input using the power source applied at the vcc and agnd pcb pads. note that the power source applied to the vcc pcb pad has a 4.5v to 5.5v input-voltage range. when operating the max15026b ev kit using separate power-supply sources at the vin connector and vcc pcb pad, apply power at the vin and pgnd connectors first and then the vcc and agnd pcb pads. configuring the output voltage (vout) vout voltage can be reconfigured between 0.6v to0.85 x vin. to configure the ev kit? output voltage, refer to the setting the output voltage section in the max15026 ic data sheet for instructions on selectingnew resistor values. capacitors c13?16 and resistors r10 and r11 pro- vide a compensation network for vout on the max15026b ev kit. refer to the inductor selection , input capacitor selection , and the compensation sections in the max15026 ic data sheet to verify whether other components needreplacement for proper operation after reconfiguring the output voltage. current-limit thresholds the max15026b ic employs a current-sensing algo-rithm using the on-resistance of the low-side mosfet as a current-sensing element to limit the inductor cur- rent. the inductor current is sensed in the converter by sensing the voltage drop across the on-resistance r dson of the low-side mosfet (n2). the max15026b ev kit? valley and sink current limits are set to approxi-mattely 16.5a and 8a, respectively. resistor r9 sets vout valley current-limit voltage thresholds (v ith ) to 59mv. the sink current-limit voltage threshold is approximately half the valley current-limitvoltage threshold. use the following equation to recon- figure the valley current-limit voltage threshold: where v ith is the valley current-limit voltage threshold in volts and r lim_ is r9 in ohms. refer to the current limit circuit (lim) and setting the valley current limit sections in the max15026 ic data sheet for further instructions on computing themax15026b ev kit valley and sink current limits. a pcb pad for resistor r8 is provided to implement foldback current-limit capabilities, if required. switching frequency the max15026b controller switching frequency is setto 600khz by resistor r14. replace resistor r14 with a new resistor value to program the switching frequency between 200khz and 2mhz. use the following equa- tion to calculate r14 when reconfiguring the switching frequency: where f sw is in hertz and r14 is in ohms. when reconfiguring the ev kit controller switching fre-quency, it may be necessary to change the compensa- tion network component to new values. refer to the compensation section in the max15026 ic data sheet for computing new compensation component values. power-good output (pgood) the max15026b ev kit provides a pcb pad to monitorthe status of the power-good output. pgood is high when vout rises 94.5% (typ) above its programmed output voltage. when vout falls below 92% (typ) of its nominal regulated voltage, pgood is pulled low. r14 17.3 10 f1 x 1 0)( f 9 sw 7 sw = + () 2 r v lim ith _ () ?= 10 50 10 6 evaluates: max15026b max15026b evaluation kit _______________________________________________________________________________________ 3 table 1. max15026b bias inputconfiguration (ju1) shunt position max15026b in pin max15026b ic input range (v) 1-2 connected to vin 5 to 16 2-3 connected to vcc 4.5 to 5.5 downloaded from: http:///
evaluates: max15026b enable control (ju2) jumper ju2 configures the max15026b ev kit? outputfor turn-on/turn-off control. install a shunt across jumper ju2 to enable vout. vout is disabled or can also be externally controlled by placing an independent voltage source at the en and agnd pcb pad when a shunt is not installed at jumper ju2. an additional pcb resistor pad (r1) is included to set the output to a desired turn- on voltage. max15026b evaluation kit 4 _______________________________________________________________________________________ table 2. enable control (ju2) shunt position en pin vout output installed connected to vcc enabled not installed pulled down to agnd through r2 disabled or voltage source applied at en pcb pad downloaded from: http:///
evaluates: max15026b max15026b evaluation kit _______________________________________________________________________________________ 5 figure 1. max15026b ev kit schematic downloaded from: http:///
evaluates: max15026b max15026b evaluation kit 6 _______________________________________________________________________________________ figure 2. max15026b ev kit component placement guide?omponent side downloaded from: http:///
evaluates: max15026b max15026b evaluation kit _______________________________________________________________________________________ 7 figure 3. max15026b ev kit pcb layout?omponent side downloaded from: http:///
evaluates: max15026b max15026b evaluation kit 8 _______________________________________________________________________________________ figure 4. max15026b ev kit pcb layout?ower layer 2 downloaded from: http:///
evaluates: max15026b max15026b evaluation kit _______________________________________________________________________________________ 9 figure 5. max15026b ev kit pcb layout?nd layer 3 downloaded from: http:///
maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. 10 __________________ maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2008 maxim integrated products is a registered trademark of maxim integrated products, inc. evaluates: max15026b max15026b evaluation kit figure 6. max15026b ev kit pcb layout?older side downloaded from: http:///
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