general description the max8546 evaluation kit (ev kit) is a fully assembled and tested circuit board that contains all the compo- nents necessary to evaluate the performance of the max8546 step-down dc-dc converter. the ev kit comes with a max8546 ic installed. the ev kit? circuit is optimized for a 10v to 24v input range and 300khz switching frequency, and delivers 2.5v at 6a to the output. to evaluate the max8545 or max8548, replace the ic with the desired part and refer to the max8545/max8546/max8548 data sheet to select the appropriate components for the ev kit. features 10v to 24v input range (max8546) 300khz operation 2.5v at 6a output foldback short-circuit protection low-cost solution evaluates the max8545, max8546, and max8548 fully assembled and tested evaluates: max8545/max8546/max8548 max8546 evaluation kit ________________________________________________________________ maxim integrated products 1 19-2963; rev 0a; 8/03 component list for pricing, delivery, and ordering information, please contact maxim/dallas direct! at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. ordering information part temp range ic package MAX8546EVKIT 0 c to +70 c 10 max designation qty description c1 1 1f 10%, 10v x5r ceramic capacitor (0603) tdk c1608x5r1a105k c2, c3 2 470f 20% , 35v al um i num el ectr ol yti c cap aci tor s (10mm ? 22mm) s anyo 35m v 470ax c4, c12 2 1f 10%, 50v x7r ceramic capacitors (1206) tdk c3216x7r1h105k c5, c8, c9 3 0.1f 10%, 50v x7r ceramic capacitors (0603) tdk c1608x7r1h104k c6, c7 2 1500f 20% , 6.3v al um i num el ectr ol yti c cap aci tor s (10mm ? 20mm) s anyo 6m v 1500ax c10 1 6800pf 10%, 50v x7r ceramic capacitor (0603) tdk c1608x7r1h682k c11 0 not installed, capacitor (0603) c13 1 1500pf 10%, 50v x7r ceramic capacitor (0603) tdk c1608x7r1h152k designation qty description d1, d2 2 100ma, 30v schottky diodes (sot23) central semiconductor cmpsh-3 l1 1 4h, 8.3a inductor sumida cep125-4r0 n1 1 dual n-channel mosfet (8-pin so) (lsfet 8.6a, 30v, 0.020 ? hsfet 6.3a, 30v, 0.035 ? ) fairchild semiconductor fds6982 q1 1 200ma, 40v npn bipolar transistor (sot23) fairchild semiconductor mmbt3904 r1 1 8.66k ? 1% resistor (0805) r2 1 4.02k ? 1% resistor (0805) r3 1 10 ? 5% resistor (0805) r4 1 68k ? 5% resistor (0805) r5, r6 2 10k ? 5% resistors (0805) r7 1 0 ? 5% resistor (0603) r8 1 3 ? 5% resistor (0603) r9 1 3 ? 5% resistor (1206) u1 1 max8546eub (10-pin max) none 1 max8546 pc board
evaluates: max8545/max8546/max8548 max8546 evaluation kit 2 _______________________________________________________________________________________ quick start recommended equipment adjustable 10v to 24v, 2a dc power supply voltmeter electronic load (set to resistive mode) procedure the max8546 ev kit is fully assembled and tested. follow these steps to verify board operation. do not turn on the power supply until all connections are completed: 1) connect a voltmeter across the vout and pgnd pads. 2) connect a 10v to 24v dc power supply to the vin and pgnd pads, with the voltage set in the 10v to 24v range. 3) turn on the power supply. 4) verify that vout is 2.5v 3% throughout the 10v to 24v input voltage range. 5) connect a 6a load between the vout and pgnd pads, and verify that the output voltage is 2.5v 3%. detailed description the max8546 ev kit contains a step-down switching dc-dc converter. the switching frequency for the max8546 is internally set at 300khz. the circuit uses two feedback resistors, r1 and r2, to set the output voltage. c10, c11, and r4 provide a compensation network for the max8546. d2 limits the initial peak inductor current during overload and short-circuit con- ditions. the evaluation circuit is designed to achieve the lowest component cost. input and output voltage range the max8546 evaluation circuit has an input range of 10v to 24v. the output is configured for 2.5v and can supply up to 6a. the pc board layout for this ev kit uses 2oz copper and is capable of conducting currents up to 10a with suitable external components. refer to the max8545/max8546/max8548 data sheet regard- ing component selection for higher current applica- tions. other output voltages the max8546 ev kit comes preset to 2.5v on vout. to set other output voltages for vout, refer to the max8545/max8546/max8548 data sheet for instruc- tions on selecting external components. current-limit protection the max8546 ev kit s current limit is determined by the current-limit threshold of the max8546 and mosfet n1 s low-side r ds(on) . use the following equation to evaluate other current limits: where the current-limit threshold of the max8546 is 165mv (typ) and lir is the ratio of the peak-to-peak inductor current to the maximum-rated output current. refer to the max8545/max8546/max8548 data sheet for a more detailed description of lir. under short-circuit conditions, the current limit folds back to approximately 20% of its threshold, reducing power dissipation. shutdown control the max8546 features a shutdown control pad that can be connected to an external (ttl) source to put the max8546 into shutdown mode. transistor q1 and resistors r5 and r6 provide the shutdown feature. a logic high at the shdn pad shuts down the output vout, and a logic low turns on the output. connect this logic signal across the shdn and gnd pads. currentlimit currentlimitthreshold mosfetsr lir i dson loadmax =+ ? ? ? ? ? ? 1 2 supplier phone fax website central semiconductor 631-435-1110 631-435-1824 www.centralsemi.com fairchild semiconductor 888-522-5372 www.fairchildsemi.com sanyo 619-661-6322 619-661-1055 www.sanyovideo.com sumida 847-545-6700 847-545-6720 www.sumida.com tdk 847-803-6100 847-390-4405 www.component.tdk.com note: please indicate that you are using the max8546 when contacting these component suppliers. component suppliers
evaluates: max8545/max8546/max8548 max8546 evaluation kit _______________________________________________________________________________________ 3 max8546 u1 v cc 3 4 5 7 1 2 8 6 4 3 5 v in bst 10 9 8 6 7 2 1 dh lx dl gnd fb vl r7 0 ? bst bst d1 c4 1 f c3 470 f 35v c2 470 f 35v pgnd gnd shdn vin 10v to 24v vout 2.5v at 6a tp2 tp1 pgnd r3 10 ? c1 1 f c9 0.1 f c12 1 f n1-b l1 4 h c8 0.1 f c6 1500 f 6.3v r9 3 ? r8 3 ? c13 1500pf c7 1500 f 6.3v n1-a r1 8.66k ? 1% r5 10k ? 1 2 3 q1 r6 10k ? r4 68k ? r2 4.02k ? 1% c10 6800pf c11 open comp/en d2 c5 0.1 f figure 1. max8546 ev kit schematic
evaluates: max8545/max8546/max8548 max8546 evaluation kit 4 _______________________________________________________________________________________ figure 2. max8546 ev kit component placement guide?omponent side figure 3. max8546 ev kit pc board layout?omponent side
evaluates: max8545/max8546/max8548 max8546 evaluation kit _______________________________________________________________________________________ 5 figure 4. max8546 ev kit pc board layout?nd layer 2 figure 5. max8546 ev kit pc board layout?cc layer 3
maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. 6 _____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 ? 2003 maxim integrated products printed usa is a registered trademark of maxim integrated products. evaluates: max8545/max8546/max8548 max8546 evaluation kit figure 6. max8546 ev kit pc board layout?older side
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