general description the max8621z evaluation kit (ev kit) is a fully assembledand tested circuit board that evaluates the max8621z dual step-down, dc-dc power-management ic for portable devices. the max8621z ev kit buck1 and buck2 4mhz hysteretic step-down dc-dc converters are preset to 1.375v and 1.8v output voltages, respec- tively, and each can supply 500ma output current. the out1 and out2 ldos each supply 2.6v (default ev kit setting) at 300ma. the out3 and out4 ldos each sup- ply 1.8v and 3v (default ev kit setting), respectively, at 150ma. proper power sequencing is built in to the max8621y/max8621z. the four ldo output voltages are pin selectable by sel1 and sel2 for flexibility. out2, out3, and out4 have individual logic-controlled shut- down. a microprocessor reset output ( reset ) monitors v out1 and warns the system of impending power loss, allowing safe shutdown. reset asserts during power-up, power-down, shutdown, and fault conditions when v out1 is below its regulation voltage. an additional 200ma dri- ver output is provided to control led backlighting or pro- vide an open-drain connection for resistors such as in feedback networks. the max8621z ev kit operates from a 2.6v to 5.5v supply voltage. the max8621z ev kit can also evaluate the max8621y. to evaluate the max8621y, order a free sample along with this ev kit. features ? two 500ma step-down dc-dc converters up to 4mhz switching frequencyadjustable output from 0.6v to 3.3v ? four low-noise ldos with pin-programmableoutput voltages ? one open-drain driver ? 30ms (min) reset timer ? power-on/off control logic and sequencing ? 4mm x 4mm x 0.8mm, 24-pin thin qfn ? fully assembled and tested evaluates: max8621y/max8621z max8621z evaluation kit ________________________________________________________________ maxim integrated products 1 19-3814; rev 0; 8/05 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 designation qty description c1 1 10? ?0%, 6.3v x5r ceramiccapacitor (0805) murata grm219r60j106k c2, c3, c5, c10 4 4.7? ?0%, 6.3v x5r ceramiccapacitors (0603) murata grm188r60j475ke19 c4 1 0.01? ?0%, 10v x5r ceramiccapacitor (0402) tdk c1005x5r1a103k c6, c8 2 150pf ?%, 50v c0g ceramiccapacitors (0402) tdk c1005c0g1h151j part temp range ic package MAX8621ZEVKIT 0? to +70? 24 tqfn (4mm x 4mm) designation qty description c7, c9, c11, c12 4 2.2? ?0%, 6.3v x5r ceramiccapacitors (0603) murata grm188r60j225ke19 ju1, ju2 2 2-pin headers ju3?u7 5 3-pin headers l1, l2 2 2.2? inductor (1210),790ma, 0.13 ? murata lqh32cn2r2m53 r1, r3 2 150k ? ?% resistors (0402) r2 1 115k ? ?% resistor (0402) r4 1 75k ? ?% resistor (0402) u1 1 max8621zetg ? shunts ? max8621z ev kit pc board downloaded from: http:///
evaluates: max8621y/max8621z quick start recommended equipment ? ne variable dc power supply capable of supplying up to 5.5v at 2a four digital multimeters (dmms) ammeter (optional) various loads (optional) procedure the max8621z ev kit is fully assembled and tested.follow the steps below to verify board operation: 1) preset the variable dc power supply to 3.7v. turn off the power supply. do not turn on the power supply until all connections are complete . 2) connect the positive lead of the power supply to thein pad on the ev kit and connect the negative lead of the power supply to the gnd pad on the ev kit. 3) to enable the max8621z, verify that jumperpwron (ju1) has a shunt across it. 4) verify that jumper en2 (ju2) has no shunt connected to it. verify that jumpers en3 (ju3), en4 (ju4), andendr (ju5) have shunts connecting pins 2 and 3. verify that jumpers sel1 (ju7) and sel2 (ju6) have all pins open (default configuration has shunts con- nected to pin 1 but does not shunt other pins). 5) connect the positive lead of a voltmeter to thebuck1 pad on the ev kit and connect the negative lead of the voltmeter to the gnd pad on the ev kit. 6) connect the positive lead of a second voltmeter to the buck2 pad on the ev kit and connect the neg-ative lead of the voltmeter to the gnd pad on the ev kit. 7) connect the positive lead of a third voltmeter to the out1 pad on the ev kit and connect the negativelead of the voltmeter to the gnd pad on the ev kit. 8) connect the positive lead of a fourth voltmeter tothe out2 pad on the ev kit and connect the nega- tive lead of the voltmeter to the gnd pad on the ev kit. 9) turn on the power supply. 10) verify that buck1 voltage is near 1.375v. connect a load, if desired, from buck1 to gnd. see table 1for maximum loads. 11) verify that buck2 voltage is near 1.8v. connect a load, if desired, from buck2 to gnd. see table 1for maximum loads. 12) verify that out1 voltage is near 2.6v. connect aload, if desired, from out1 to gnd. see table 1 for maximum loads. 13) verify that out2 voltage is near 2.6v. connect aload, if desired, from out2 to gnd. see table 1 for maximum loads. 14) to verify out3 and out4, move the shunt on the respective jumpers to pins 1 and 2 and use a volt-meter to verify output voltage of 1.8v and 3.0v, respectively. 15) connect loads from outputs out3 and out4 to gndif desired. see table 1 for maximum load currents. detailed description the max8621z ev kit provides two step-down dc-dcconverters with 500ma output current capability and four ldo outputs of 2.6v at out1, 2.6v at out2, 1.8v at out3, and 3v at out4. a 60ms (typ) reset and a 1.3 ? , 200ma driver are also available. table 1 lists output volt- ages and maximum currents. the ev kit incorporates jumpers ju2, ju3, and ju4 to enable or disable out2, out3, and out4, respectively. tables 2 and 3 detail the jumper functions. the ldo output voltages?ut1, out2, out3, and out4?re programmable by the logic states of sel1 and sel2. max8621z evaluation kit 2 _______________________________________________________________________________________ component suppliers supplier part phone website murata inductors, capacitors 814-237-1431 www.murata.om tdk capacitors 888-835-6646 www.component.tdk.com vishay resistors 402-563-6866 www.vishay.com note: indicate that you are using the max8621z ev kit when contacting these component suppliers. downloaded from: http:///
programming ldo output voltages as shown in table 4, the ldo output voltages?ut1,out2, out3, and out4?re pin programmable by the logic states of sel1 and sel2. sel1 and sel2 are tri-level inputs: in, open, and gnd. the input voltage, v in , must be greater than the selected out1, out2, out3, and out4 voltages. the logic states of sel1and sel2 are to be programmed only during power-up. once the out_ voltages are programmed, their values do not change by changing sel_ unless the max8621z power is cycled. evaluates: max8621y/max8621z max8621z evaluation kit _______________________________________________________________________________________ 3 table 1. default ev kit output voltages and maximum currentstable 2. ju1 and ju2 jumper function table 3. ju3, ju4, and ju5 jumper functions table 4. sel1 (ju7) and sel2 (ju6) output voltage selection (max8621z) output voltage (v) maximum current (ma) buck1 1.375 500 buck2 1.8 500 out1 2.6 300 out2 2.6 300 out3 1.8 150 out4 3.0 150 * default position label (jumper) output shunt connected shunt not connected pwron (ju1) power-on of max8621z max8621z on* max8621z off en2 (ju2) out2 off on* * default position label (jumper) output pins 1 and 2 pins 2 and 3 en3 (ju3) out3 on off* en4 (ju4) out4 on off* endr (ju5) dr dr low dr high impedance* * default position sel1 (ju7) sel2 (ju6) out1 (v) out2 (v) out3 (v) out4 (v) in in 2.8 2.6 3.0 3.0 in open 2.6 2.6 3.0 3.0 in gnd 2.6 2.6 2.9 2.9 open in 2.6 2.6 3.0 3.3 open* open* 2.6 2.6 1.8 3.0 open gnd 2.6 2.6 2.8 3.0 gnd in 2.9 3.1 1.8 1.5 gnd open 3.0 2.9 2.9 2.9 gnd gnd 3.0 2.5 2.9 2.9 note: where in is pins 1 and 2 shunted together, gnd is pins 2 and 3 shunted together, and open is with no shunt on the respectivejumper. downloaded from: http:///
evaluates: max8621y/max8621z ldo output capacitor selection the max8621z ev kit has a 4.7? ceramic capacitor, c5 in figure 1, between out1 and ground, and a second 4.7? ceramic capacitor, c10 in figure 1, between out2 and ground for 300ma applications. for 150ma applica- tions, capacitor c5 and c10 can be decreased to 2.2? ceramic capacitors. out3 and out4 have a 2.2? ceramic capacitor connected between each respective output and ground, c11 and c12 in figure 1. if an ldo output is not expected to exceed 50ma, then that respec- tive output capacitor value can be reduced to 1 f. evaluating other step-down output voltages select an output voltage for buck1 between 0.6v and3.3v by connecting fb1 to a resistor-voltage-divider between lx1 and gnd. ensure r2 (figure 1) provides a reasonable bias current in the resistor-divider. a wide range of resistor values is acceptable, but for ease of ev kit modification, choose r1 to be 150k ? . then, r2 (figure 1) is given by: table 5 provides suggested component values, r1,r2, and c6 in figure 1, for various step-down output voltages. for buck2, r3 and r4 are calculated using the same method. reset output ( reset ) the reset circuit is active both at power-up and power-down. reset asserts low when v out1 drops below 87% (typ) of regulation. reset deasserts 60ms after v out1 rises above 87% (typ) of regulation. reset is pulled up through an internal 14k ? resistor to out1. dr driver the max8621z includes a 1.3 ? , 200ma n-channel mosfet open-drain output that is controlled by endr.this output can be used to drive leds or allow adjustable output voltages. refer to the max8621z data sheet for more details. evaluating the max8621y for evaluating the max8621y, carefully remove themax8621z and install the max8621y. all other compo- nents can remain the same. rk kv vv out 2 150 0 6 06 () . . ? ? = max8621z evaluation kit 4 _______________________________________________________________________________________ table 5. suggested component values for various step-down output voltages output voltage (v) r1 (k ? ) r2 (k ? ) c6 (pf) 0.9 150 300 150 1.1 150 178 150 1.2 150 150 150 1.3 150 130 150 1.4 150 113 150 1.5 150 100 150 1.8 150 75 150 downloaded from: http:///
evaluates: max8621y/max8621z max8621z evaluation kit _______________________________________________________________________________________ 5 r2115k ? c6 150pf r1150k ? c72.2 f l1 2.2 h gnd buck1 r475k ? c8 150pf r3150k ? c92.2 f l2 2.2 h gnd buck2 reset out2 c104.7 f out3 c112.2 f in c1 10 f c2 4.7 f out4 c122.2 f dr gnd in c3 4.7 f in out1 c54.7 f out1 gnd ju1 ju2 12 3 ju3 12 3 ju4 12 3 ju6 12 3 ju5 12 3 ju7 out1 c4 0.01 f max8621z u1 2210 16 14 87 out1 lx1fb1 pgnd1 lx2fb2 in1in2 in3 pwron en2 en3 1223 1 24 21 2 pgnd2 reset out2out3 out4 dr 4 17 18 15 5 2011 9 13 6 19 refbp sel2 sel1 endr en4 3 gnd figure 1. max8621z ev kit schematic 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. 6 _____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2005 maxim integrated products printed usa is a registered trademark of maxim integrated products, inc. evaluates: max8621y/max8621z max8621z evaluation kit figure 2. max8621z ev kit component placement guide component side figure 3. max8621z ev kit pc board layout?omponent side figure 4. max8621z ev kit pc board layout?older side downloaded from: http:///
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