general description the max1938 evaluation kit (ev kit) is a fully tested and assembled power supply that demonstrates the full functionality of the max1937/max1938/max1939 family of synchronous, two-phase, step-down controllers. the circuit operates from an input supply range of 8v to 14v and provides vid-controlled cpu core voltage with up to 60a of output current. the ev kit comes with the max1938 installed, which provides a 5-bit vid code interface to meet intel voltage-regulator module (vrm) 9.0/9.1 specifications. the max1937 and max1939 can also be evaluated using the same board by replacing the max1938. the max1937 supports the amd hammer cpu vid codes, and the max1939 supports the amd athlon mobile cpu vid codes. features ?.75% output voltage accuracy up to 90% efficiency?o heatsinks up to 60a output current quick-pwm architecture reduces output capacitors 8v to 14v input range (8v to 22v with component change) 500khz output ripple frequency max1937: amd hammer compatible max1938: intel vrm9.0/9.1 compatible max1939: amd athlon mobile compatible controlled (on-the-fly) vid voltage transition power-good (pwrgd) output user-programmable voltage positioning fully assembled and tested evaluates: max1937/max1938/max1939 max1938 evaluation kit ___________________________________________________________________________________________ maxim integrated products 1 designation qty description c1, c4 2 2.2f, 10v x5r capacitors (0805) taiyo yuden lmk212bj225kg or equivalent c2 1 2.2f, 16v x7r capacitor (1206) taiyo yuden emk316bj225ml or equivalent c3, c7 2 0.22f, 10v x7r capacitors (0603) taiyo yuden lmk107bj224ka or equivalent c5 1 0.47f, 10v x5r capacitor (0603) taiyo yuden lmk107bj474ka or equivalent c6 1 47pf, 50v c0g capacitor (0603) murata grm39c0g470j050ad or equivalent c8, c9, c17, c32 4 1000pf, 50v x7r capacitors (0603) murata grm39x7r102k or equivalent c10 c14 5 1f, 10v x7r capacitors (0805) taiyo yuden lmk212bj105mg or equivalent component list ordering information 19-2961; rev 0; 7/03 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. part temp range ic package MAX1938EVKIT -40 c to +85 c 28 qsop designation qty description c15 1 0.01f, 50v x7r capacitor (0603) taiyo yuden umk107b103kz or equivalent c16 0 not installed (0603) c18 c23 6 330f, 25v al electrolytic capacitors sanyo 25mv330wx c24 c31 8 560f, 4v oscon (e) capacitors sanyo 4sp560m c33, c34, c45, c46 4 10f, 16v x5r capacitors (1210) taiyo yuden tmk325bj106mm or equivalent c35 c44, c54 c57 0 open c47 c53 0 open con1 con6 6 banana jacks, noninsulated d1 1 diode (sod123) central semiconductor cmhd4448 d2 1 dual schottky diodes sot23 central semiconductor cmpsh-3a note: to evaluate the max1937 or max1939, request free sam- ples along with the MAX1938EVKIT. quick-pwm is a trademark of maxim integrated products. intel is a registered trademark of intel corp. athlon is a trademark of advanced micro devices, inc.
2 ______________________________________________________________________________________ evaluates: max1937/max1938/max1939 max1938 evaluation kit required equipment the following equipment is required before beginning: 8v to 14v, at least 150w power supply or battery adjustable load capable of sinking 60a at 0.8v two digital multimeters (dmms) oscilloscope note: active electronic loads have a minimum input voltage required when sinking current. make sure that the load is capa- ble of sinking the necessary current at the lowest voltage. take into account the voltage drop in the wires connecting the ev kit to the load. to minimize the voltage drop in the wires, two con- nectors are provided on the ev kit for the output allowing two wires to be connected in parallel. it is also acceptable to use two loads, each sinking half the current. quick start follow these steps to verify operation of the max1938 ev kit. when making connections to the high-current input and output, make sure that the wire gauge is heavy enough to handle the necessary current and mini- mize voltage drop in these wires. do not turn on the power supply until all connections are completed: 1) preset the power supply between 8v and 14v. turn off the power supply. 2) select the desired output voltage using the vid_ jumpers (see table 1 for a list of jumper settings and corresponding output voltages). 3) verify that the pins of jumper en are not shorted. 4) connect the positive (+) power-supply output to the banana connector labeled in on the max1938 ev kit. 5) connect the negative (-) power-supply output to the banana connector labeled gnd located near the center of the max1938 ev kit. 6) if available, connect the positive (+) power-supply sense lead to the pad labeled in, and connect the negative (-) power-supply sense lead to the pad labeled gnd (next to in). component list (continued) designation qty description d3, d4 0 not installed (d-pak) ju4 ju9 6 2-pin headers l1, l2 2 0.60h inductors panasonic etqp1h0r6bfa bi hm7340r50 (alternate) n1, n2, n3, n6, n7, n8 6 n-channel mosfets (d-pak) irf irlr7811w n4, n5, n9, n10 4 n-channel mosfets (d 2 -pak) fairchild isl9n303as3st n11 n22 0 not installed, 8-pin so r1 1 10 ? 5% resistor (0603) r2 1 51.1k ? 1% resistor (0603) r3 1 200k ? 1% resistor (0603) r4 1 68.1k ? 1% resistor (0603) r5, r8 2 3.3 ? 5% resistors (0603) r6 1 100k ? 5% resistor (0603) r7 1 120k ? 5% resistor (0603) r9, r10 2 200 ? 5% resistors (0603) r11, r12, r14, r15 4 2m ? 1%, 1w resistors (2512) vishay wsl2512 or panasonic erjm1wtf2mu r17, r18 2 100 ? 5% resistors (0603) r19 0 not installed (0603) r20 0 not installed (0603) pc board short u1 1 max1938eei qsop u2 1 6v linear regulator (d-pak) fairchild ka78m06r or texas instruments ua78m06cktp none 6 shunts part of kit 1 MAX1938EVKIT pc board component suppliers supplier phone website bi technologies 714-447-2345 www.bitechnologies.com central semiconductor 631-435-1110 www.centralsemi.com fairchild 408-721-2181 www.fairchildsemi.com international rectifier 310-322-3331 www.irf.com kamaya 260-489-1533 www.kamaya.com murata 770-436-1300 www.murata.com panasonic 714-373-7939 www.panasonic.com sanyo 619-661-6835 www.sanyo.com taiyo yuden 408-573-4150 www.t-yuden.com vishay 402-564-3131 www.vishay.com
_______________________________________________________________________________________ 3 7) if the power supply does not have sense connec- tions, use a dmm to monitor the input voltage on the board. connect the positive terminal of dmm 1 to the pad labeled in, and connect the common (com) or ground terminal of the dmm to the pad labeled gnd (next to the in pad). 8) if using an active load, connect the positive side of the load to the banana connectors labeled out (located at the top of the ev kit board). two out connections are provided on the board so that two parallel wires can be used to connect the load. alternatively, two loads can be connected in parallel, one to each out connector. connect the negative side of the load to the banana connectors labeled gnd (located near the top of the board by the out connectors). two gnd connections are provided for paralleling wires to the load or connecting multiple loads. 9) use a dmm to monitor the output voltage. connect the positive (+) terminal of dmm 2 to the pad labeled out (located in the upper-left corner of the ev kit board as shown in figure 3). connect the common (com) or ground terminal of the dmm to the gnd pad (located next to the out pad in the upper left corner). 10) if desired, connect an oscilloscope probe to the connector located between the out and gnd banana connectors. the oscilloscope can then be used to observe the output ripple. 11) turn on the power supply. 12) using dmm 2, verify that the output voltage match- es the voltage selected with the vid_ inputs. 13) set the active load to the desired current (up to 60a), or connect a passive load to the output. 14) verify that the correct output voltage appears on dmm 2. 15) to verify operation of the enable/shutdown feature, connect the pins of jumper en using the shunt pro- vided. the max1938 shuts down and the output voltage drops to zero. 16) remove the shunt across jumper en. the max1938 powers up and the output voltage returns to its nominal value. 17) to use the on-the-fly vid code feature, change the vid_ jumper settings (see table 1). the output voltage changes to the newly selected value at a controlled rate without overshoot or undershoot. detailed description setting the output voltage (vid_) the max1938 ev kit uses a 5-bit vid interface for select- ing the output voltage. table 1 shows the output voltages corresponding to each vid code. either each vid_ input can be driven as a digital input, or the code can be set using the jumpers provided on the board. if the jumpers are used, short the pins of the vid_ jumper with the pro- vided shunts to set the vid_ bits to logic 0. remove the shunt from the jumper to set the corresponding bit to logic 1. if the vid_ inputs are driven as digital inputs, remove all the shunts from the vid_ jumpers. the vid code can be changed either when the convert- er is off or when it is functioning (on-the-fly). when the vid code is changed on-the-fly, the output voltage ramps up or down at a controlled rate until the new voltage is reached (refer to the max1937/max1938/ max1939 data sheet for more details). enable input (en) the enable input can be used to enable or shut down the controller. this can be done either by using the en jumper provided on the ev kit, or by driving the en input as a digital input. when using the jumper, short the pins of the en jumper to shut down or remove the short to enable the output (see table 2). when using en as a digital input, remove the shunt from the en jumper. drive en high to enable the output or drive en low for shutdown. power-good output (pwrgd) power-good (pwrgd) is an open-drain output with a 100k ? external pullup resistor to vdd. this output is low if the output voltage deviates more than 12.5% from the value set by the vid code, and high when the out- put is in regulation. pwrgd is low when the part is in shutdown or during startup. customizing the max1938 evkit evaluating the max1937 or max1939 the max1938 ev kit comes with the max1938 installed, providing a vid code interface to meet intel vrm9.0/vrm9.1 specifications. the max1937 and max1939 can also be evaluated using the same board by replacing the max1938. the max1937 supports the amd hammer cpu vid codes, whereas the max1939 supports the amd athlon mobile cpu vid codes. to evaluate the max1937 or max1939, carefully remove the max1938 from the ev kit and replace it with the new part. free samples of the max1937 and max1939 can be obtained from maxim. the ev kit can be preconfigured with the max1937 or max1939 upon request. evaluates: max1937/max1938/max1939 max1938 evaluation kit
4 ______________________________________________________________________________________ evaluates: max1937/max1938/max1939 max1938 evaluation kit v out (v) vid4 vid3 vid2 vid1 vid0 max1937 max1938 max1939 00000 1.550 1.850 2.000 00001 1.525 1.825 1.950 00010 1.500 1.800 1.900 00011 1.475 1.775 1.850 00100 1.450 1.750 1.800 00101 1.425 1.725 1.750 00110 1.400 1.700 1.700 00111 1.375 1.675 1.650 01000 1.350 1.650 1.600 01001 1.325 1.625 1.550 01010 1.300 1.600 1.500 01011 1.275 1.575 1.450 01100 1.250 1.550 1.400 01101 1.225 1.525 1.350 01110 1.200 1.500 1.300 01111 1.175 1.475 shutdown 10000 1.150 1.450 1.275 10001 1.125 1.425 1.250 10010 1.100 1.400 1.225 10011 1.075 1.375 1.200 10100 1.050 1.350 1.175 10101 1.025 1.325 1.150 10110 1.000 1.300 1.125 10111 0.975 1.275 1.100 11000 0.950 1.250 1.075 11001 0.925 1.225 1.050 11010 0.900 1.200 1.025 11011 0.875 1.175 1.000 11100 0.850 1.150 0.975 11101 0.825 1.125 0.950 11110 0.800 1.100 0.925 11111 shutdown shutdown shutdown table 1. vid programmed output voltage (vid0 vid4) en jumper function open enable the output short shut down the output table 2. en jumper functions note: in the above table, a zero indicates vid_ is driven low or the jumper pin is connected. a 1 indicates vid_ is driven high or th e jumper is not connected.
_______________________________________________________________________________________ 5 evaluates: max1937/max1938/max1939 max1938 evaluation kit dh1 lx1 vid0 vid2 vid1 vid3 vid4 en time vpos ref ilim gnd gnds bst1 ol1 cs1 vlg pgnd cs2 dl2 bst2 lx2 dh2 fb pwrgd 26 28 13 12 10 11 8 1 2 4 5 6 3 7 9 25 27 23 24 22 19 20 16 18 17 14 15 21 max1938 u1 r8 3.3 ? n19 n18 n17 n8 n7 n6 n22 n21 n20 n10 n9 d4 l2 0.60 h r12 2m ? r11 2m ? r9 200 ? v cc c8 1000pf c9 1000pf n13 n12 n11 n3 n2 n1 n16 n15 n14 n4 n5 d3 out l1 0.60 h r15 2m ? r14 2m ? r10 200 ? v cc v cc r6 100k ? pwrgd c32 1000pf r9 200 ? d2 r5 3.3 ? r8 3.3 ? c3 0.22 f c7 0.22 f c14 1 f v cc v dd c17 1000pf r17 100 ? r4 68.1k ? r2 51.1k ? r3 200k ? r7 120k ? c6 47pf c5 0.47 f vid1 vid2 vid3 vid4 en vid0 ju5 ju6 ju7 ju8 ju9 ju4 ju2 open r20 short c16 open ju3 open r1 10 ? v dd c4 2.2 f d1 c15 0.0i f c1 2.2 f c2 2.2 f 13 2 in out u2 gnd ka78m06 figure 1. max1938 ev kit schematic (sheet 1 of 2)
6 ______________________________________________________________________________________ evaluates: max1937/max1938/max1939 max1938 evaluation kit c18 330 f c19 330 f c20 330 f c21 330 f c22 330 f c23 330 f c33 10 f c34 10 f c35 open c36 open con1 ju1 con2 vcc c26 560 f c25 560 f c24 560 f c27 560 f c28 560 f c29 560 f c30 560 f c31 560 f c10 1 f c11 1 f c12 1 f c13 1 f con3 con5 con4 con6 out c43 open c44 open c45 10 f c46 10 f c42 open c38 open c39 open c40 open c41 open c37 open vcc c49 open c48 open c47 open c50 open c51 open c52 open c53 open c54 open c55 open c56 open c57 open out ju10 probe_jack figure 1. max1938 ev kit schematic (sheet 2 of 2)
_______________________________________________________________________________________ 7 evaluates: max1937/max1938/max1939 max1938 evaluation kit figure 2. max1938 ev kit component placement guide component side figure 3. max1938 ev kit pc board layout?omponent side
8 ______________________________________________________________________________________ evaluates: max1937/max1938/max1939 max1938 evaluation kit figure 4. max1938 ev kit pc board layout?nner layer 2 figure 5. max1938 ev kit pc board layout?nner layer 3
evaluates: max1937/max1938/max1939 max1938 evaluation kit 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. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 _____________________ 9 ? 2003 maxim integrated products printed usa is a registered trademark of maxim integrated products. figure 6. max1938 ev kit pc board layout?older side
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