19-2876; Rev 0; 5/03 MAX1955 Evaluation Kit Ordering Information PART TEMP RANGE MAX1955EVKIT 0°C to +70°C Features ♦ Configured for 1.8V and 1.5V Outputs ♦ MAX1955: 2.25V to 5.5V Input Supply Range ♦ MAX1956: 1.6V to 5.5V Input Supply Range ♦ Up to 25A Current for Each Output ♦ ±4% Voltage Margining ♦ Foldback Current Limit ♦ Selectable Voltage Sequencing ♦ Independent ON/OFF Control ♦ Synchronizable to an External Clock ♦ Fully Assembled and Tested IC PACKAGE 28 Thin QFN 5mm x 5mm Component List DESIGNATION QTY DESCRIPTION 7 10µF ±20%, 6.3V X5R ceramic capacitors (0805) Panasonic ECJ2FB0J106M or Taiyo Yuden JMK212BJ106MG C8, C9, C29 3 0.47µF ±20%, 10V X5R ceramic capacitors (0603) Taiyo Yuden LMK107BJ474MA C10, C17 0 Not installed, POSCAPs C11, C12, C13, C18 4 680µF, 2.5V, 8mΩ POSCAPs Sanyo 2R5TPD680M8 C14, C16 0 Not installed (0603) C15, C33 2 470µF, 6.3V POSCAPs Sanyo 6TPB470M C1–C7 C19, C20 2 0.015µF ±10%, 25V X7R ceramic capacitors (0603) Taiyo Yuden TMK107B153KZ C21, C22, C23, C30 4 4700pF ±10% X7R ceramic capacitors (0603) Murata GRM188R71H472K C24, C27 2 6800pF ±10% X7R ceramic capacitors (0603) Murata GRM188R71H682K C25, C26 2 33pF ±0.1pF, 50V C0G ceramic capacitors (0603) Murata GRM1885C1H330J DESIGNATION QTY DESCRIPTION C28 1 0.22µF ±10%, 10V X7R ceramic capacitor (0603) Taiyo Yuden LMK107BJ224KA C31, C32 2 82pF ±5%, 50V C0G ceramic capacitors (0402) Murata GRP1555C1H820J C34 1 4.7µF ±10%, 6.3V X5R ceramic capacitor (0603) Panasonic ECJ1VB0J475K or equivalent D1–D4 4 Schottky diodes (SOT323) Central Semiconductor CMSSH-3 D5, D6 0 Not installed (SMC) Central Semiconductor CMSH5-20 J1–J4 0 Not installed, scope probe connectors JU1, JU2, JU3 3 3-pin headers JU4, JU5 2 2-pin headers L1, L2 2 0.3µH, 35A, 1.5mΩ inductors Sumida CDEP125(U)-0R3 L3 1 4.7µH inductor TDK LDR655312T-4R7W N1, N2, N8, N9 4 N-channel MOSFETs (8-pin SO PowerPak) Vishay Si7892DP ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 Evaluates: MAX1955/MAX1956 General Description The MAX1955 evaluation kit (EV kit) is a fully assembled and tested circuit board for evaluating the MAX1955 dualPWM step-down controller. The board comes with the MAX1955 installed, but can also be used to evaluate the MAX1956. The EV kit is configured to operate from a 2.25V to 5.5V input supply range and provides 1.8V and 1.5V outputs capable of delivering 25A each. By changing appropriate external components, the output voltage can be set from 0.8V to 0.9 x VIN. By using the MAX1956, the input supply range can be extended from 1.6V to 5.5V. Evaluates: MAX1955/MAX1956 MAX1955 Evaluation Kit Component List (continued) DESIGNATION QTY N3, N4, N7, N10 0 N5, N6, N11, N12 Q1, Q2 4 2 DESIGNATION QTY R9, R14 2 100kΩ ±1% resistors (0603) R10 1 200kΩ ±1% resistor (0603) N-channel MOSFETs (8-pin SO) Vishay Si4842DY R11 1 60.4kΩ ±1% resistor (0603) R12 1 56.2kΩ ±1% resistor (0603) NPN transistors (SOT23) ON Semiconductor MMBT3904LT1 R13 1 10Ω ±5% resistor (0603) R15, R16, R17 0 Not installed (0603), PC board shorts 75kΩ ±1% resistor (0603) DESCRIPTION Not installed (8-pin SO) DESCRIPTION R1, R23 0 Not installed (0603) R18 1 R2 1 7.15kΩ ±0.1% resistor (0603) R19 1 90.9kΩ ±1% resistor (0603) R3, R6 2 8.06kΩ ±0.1% resistors (0603) R24 1 510Ω ±5% resistor (0603) R4 1 10kΩ ±0.1% resistor (0603) R29–R32 4 10kΩ ±5% resistors (0603) U1 1 MAX1955ETI — 5 Shunts, position 2 15kΩ ±5% resistor (0603) — 4 Rubber feet 18kΩ ±5% resistor (0603) — 1 MAX1955 EV kit PC board R5, R20, R21, R22, R25–R28 8 1Ω ±5% resistors (0603) R7 1 R8 1 Component Suppliers SUPPLIER PHONE WEBSITE Central Semiconductor 631-435-1110 www.centralsemi.com International Rectifier 310-322-3331 www.irf.com Murata 814-237-1431 www.murata.com Panasonic 714-373-7939 www.panasonic.com Sanyo 619-661-6835 www.sanyo.com Sumida 847-545-6700 www.sumida.com Taiyo Yuden 408-573-4150 www.t-yuden.com TDK 847-803-6100 www.component.tdk.com Vishay 408-970-5715 www.vishay.com Note: Please indicate that you are using the MAX1955/MAX1956 when contacting these component suppliers. Quick Start The MAX1955 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) Verify the shorts on JU2 and JU3 are across pins 2 and 3. 2) Verify the pins of JU4 and JU5 are not shorted. 3) Preset the input power supply to between 2.25V and 5.5V. 2 4) Turn the power supply off. 5) Connect the positive power-supply terminal to the EV kit pads labeled IN. 6) Connect the power-supply ground to the EV kit pads labeled PGND. 7) Connect a load and voltmeter from OUT1 to PGND and another load and voltmeter from OUT2 to PGND. 8) Turn on the input power supply and verify the voltage from OUT1 to PGND is 1.5V and the voltage from OUT2 to PGND is 1.8V. _______________________________________________________________________________________ MAX1955 Evaluation Kit Evaluating the MAX1956 The MAX1955 EV kit comes with the MAX1955 installed, but can also be used to evaluate the MAX1956. To evaluate the MAX1956, carefully remove the MAX1955 from the PC board and replace it with the MAX1956. After installing the MAX1956, inspect all connections with an ohmmeter to verify there are no solder bridges or open connections before powering up the EV kit. Setting the Output Voltages The MAX1955 uses a pair of feedback resistors to set the output voltage for each output. In the MAX1955 EV kit, OUT1 is preset to 1.5V and OUT2 is preset to 1.8V. Each output can be set to any voltage from 0.8V to 0.9 x VIN. Use the following procedure to change the output voltage: 1) Change the upper feedback resistors (R2 and R4) to set the output voltage. Use the following formulas to calculate the values of the resistors: V R2 = R 3 OUT1 − 1 0.8 where R3 is 8.06kΩ and VOUT1 is the desired output voltage of OUT1, and: V R4 = R6 OUT2 − 1 0.8 where R6 is 8.06kΩ and VOUT2 is the desired output voltage of OUT2. 2) The output capacitors on the MAX1955 EV kit are rated for 2.5V. For higher output voltages, higher voltage-rated capacitors should be used. 3) Change the current-limit resistors (R11 and R18 for OUT1, R12 and R19 for OUT2). Refer to the MAX1955/MAX1956 data sheet for information on calculating values for these resistors. 4) Refer to the MAX1955/MAX1956 data sheet to select the optimum inductor, output capacitors, and compensation components. Clock Synchronization Input (SYNC) The MAX1955 EV kit can be synchronized to an external clock from 1080kHz to 1320kHz. Connect the clock signal to SYNC and connect the clock-signal ground to GND. Each of the step-down controllers switch at 1/2 the frequency applied to SYNC and are 180° out-ofphase with each other. To use the internal clock, leave SYNC unconnected, and each controller switches at 600kHz and is 180° out-of-phase with each other. Output Sequencing (SEQ) The outputs can be set to power up at the same time, or OUT1 can be set to power up first and power down last. For simultaneous power-up/-down, short pins 1 and 2 of JU1 (Table 1). To make OUT1 power up first and power down last, short pins 2 and 3 of JU1. Evaluating Voltage Margining A voltage-margining feature is provided on the MAX1955 and MAX1956. This allows the output voltages to be shifted up or down by 4%. Voltage margining is controlled by JU2 and JU3 (Table 2). To ensure proper startup, verify that JU2 and JU3 are shorted between pins 2 and 3 (normal operation) when power is first applied to the EV kit. Evaluating Shutdown Shutdown mode turns off the IC and reduces the input current. JU2 and JU3 control the shutdown feature (Table 2). There are also individual shutdown inputs provided on the EV kit (EN1 and EN2). These inputs allow each output to be shut down individually, but do not completely power down the IC. For convenience, jumpers are provided to control the EN_ inputs. With no connection to the EN_ pads, short the pins of JU4 and JU5 to shut down OUT1 and OUT2, respectively. Remove the short to enable the outputs (Tables 3 and 4). To control individual shutdown with a logic source, remove the shorts from JU4 and JU5 and connect the logic source to the EN_ pad. Drive EN_ logic high for shutdown or logic low to enable the output. Refer to the MAX1955/MAX1956 data sheet for details. _______________________________________________________________________________________ 3 Evaluates: MAX1955/MAX1956 Detailed Description Evaluates: MAX1955/MAX1956 MAX1955 Evaluation Kit Table 1. JU1 Functions JU1 POSITION SEQ CONNECTION Table 3. JU4 Functions SEQUENCING 1 and 2 GND OUT1 and OUT2 power up/down simultaneously 2 and 3 VDD OUT1 powers up first and powers down last JU4 POSITION OPEN SHORT FUNCTION OUT1 enabled or controlled from EN2 input OUT1 shutdown Table 4. JU5 Functions JU5 POSITION Table 2. JU2 and JU3 Functions JU2 POSITION 4 JU3 POSITION OPEN SHORT FUNCTION OUT2 enabled or controlled from EN2 input OUT2 shutdown FUNCTION 1 and 2 1 and 2 Shutdown 1 and 2 2 and 3 -4% margining 2 and 3 1 and 2 +4% margining 2 and 3 2 and 3 Enable (normal operation) _______________________________________________________________________________________ _______________________________________________________________________________________ OUT1 J1 PGND SYNC CTL1 CTL2 VIN C10 C33 470µF 3 2 1 JU3 C11 680µF C15 470µF 3 2 1 JU2 C12 680µF R14 100kΩ R10 200kΩ R9 100kΩ R3 8.06kΩ R1 C16 R2 7.15kΩ C31 82pF VDD R22 1Ω C30 4700pF L1 0.3µH C23 4700pF R21 1Ω C1 10µF JU1 3 2 1 D5 N3 C2 10µF IN EN1 N6 N2 C3 10µF JU4 R30 10kΩ C25 33pF R7 15kΩ D3 C8 0.47µF R15 SHORT N4 R29 10kΩ LX1P R26 1Ω C24 6800pF N5 N1 L3 4.7µH VDD D1 R27 1Ω 17 5 6 9 8 22 28 26 1 2 3 4 25 VIN C19 0.015µF R24 510Ω DH1 Q1 SEQ SYNC EN COMP1 FB1 PGND2 PGND1 PGND DL1 LX1 U1 MAX1955 23 VIN BST1 LXB C34 4.7µF IN Evaluates: MAX1955/MAX1956 IN MAX1955 Evaluation Kit Figure 1. MAX1955 EV Kit Schematic (Sheet 1 of 2) 5 IN 6 Figure 1. MAX1955 EV Kit Schematic (Sheet 2 of 2) _______________________________________________________________________________________ IN EN2 MAX1955 U1 VDD1 27 VDD JU5 AVDD ILIM2 ILIM1 GND1 GND REF COMP2 FB2 DL2 LX2 DH2 16 15 7 10 12 11 13 14 21 20 19 VDD2 18 BST2 24 R16 SHORT D4 R32 10kΩ R31 10kΩ R8 18kΩ N10 C29 R13 0.47µF 10Ω C28 0.22µF C26 33pF R28 1Ω C20 0.015µF R25 1Ω C9 0.47µF D2 Q2 R12 56.2kΩ R11 60.4kΩ N8 R18 75kΩ R19 90.9kΩ N12 L2 LX2P 0.3µH C27 6800pF N11 N7 VDD C21 4700pF R5 1Ω OUT1 LX1P R6 8.06kΩ OUT2 D6 LX2P C7 10µF N9 C14 J4 C32 82pF R4 10kΩ C22 4700pF R20 1Ω J3 R23 C17 C18 680µF R17 SHORT C13 680µF C4 10µF GND PGND PGND C5 10µF J2 OUT2 C6 10µF Evaluates: MAX1955/MAX1956 MAX1955 Evaluation Kit MAX1955 Evaluation Kit Evaluates: MAX1955/MAX1956 Figure 2. MAX1955 EV Kit Component Placement Guide—Component Side Figure 3. MAX1955 EV Kit Component Placement Guide—Solder Side _______________________________________________________________________________________ 7 Evaluates: MAX1955/MAX1956 MAX1955 Evaluation Kit Figure 4. MAX1955 EV Kit PC Board Layout—Component Side Figure 5. MAX1955 EV Kit PC Board Layout—Layer 2 8 _______________________________________________________________________________________ MAX1955 Evaluation Kit Evaluates: MAX1955/MAX1956 Figure 6. MAX1955 EV Kit PC Board Layout—Layer 3 Figure 7. MAX1955 EV Kit PC Board Layout—Solder Side 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. 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