19-1893; Rev 0; 1/01 MAX1775 Evaluation Kit Features ♦ +2.7V to +5.5V Input Range ♦ Output Voltages +3.3V Output at 1.5A +1.8V Output at 500mA ♦ Outputs are Adjustable with Resistors ♦ Internal MOSFET Switches (Core Output) ♦ 5µA (typ) IC Shutdown Current ♦ Switching Frequency Up to 1.25MHz ♦ Surface-Mount Components ♦ Fully Assembled and Tested Ordering Information PART TEMP. RANGE MAX1775EVKIT 0°C to +70°C IC PACKAGE 16 QSOP Component List DESIGNATION C1 QTY 1 DESCRIPTION 10µF, 25V X5R ceramic capacitor (1812) Taiyo Yuden TMK432BJ106KM C2, C5 2 1µF, 25V X7R ceramic capacitors (1206) Taiyo Yuden TMK316BJ105KL C3 1 47µF, 6.3V low-ESR electrolytic capacitor (POSCAP) Sanyo 6TPA47M 1 47µF ±20%, 6.3V tantalum capacitor (C) Sprague-Vishay 592D476X06R3C2T or AVX TPSC476M016R0350 recommended C4 C6 C7, C8 C9, C10 1 2 0 0.22µF, 25V X7R ceramic capacitor (1206) Taiyo Yuden TMK316BJ224KF 10µF, 6.3V X5R ceramic capacitors (1206) Taiyo Yuden JMK316BJ106KL Not installed, capacitors (0805) DESIGNATION QTY DESCRIPTION D1 0 Not installed, Schottky diode Nihon EC31QS04 optional L1 1 5.0µH, 2.4A inductor Sumida CDRH6D28-5R0NC L2 1 5.4µH, 1.6A inductor Sumida CDRH5D18-5R4NC P1A/P1B 1 +30V/-20V, 5.5A/4.0A N/P-channel MOSFET (SO-8) Fairchild Semiconductor FDS8928A R1 1 24.3kΩ ±1% resistor (0805) R2 1 30.1kΩ ±1% resistor (0805) R3 1 0.033Ω ±1%, 0.5W resistor (2010) Dale WSL-2010-R033-1% R4 1 66.5kΩ ±1% resistor (0805) R5 1 40.2kΩ ±1% resistor (0805) U1 1 MAX1775EEE (16 QSOP) JU1, JU2 2 3-pin headers None 2 Shunts (JU1, JU2) None 1 MAX1775 PC board None 1 MAX1775 data sheet None 1 MAX1775 EV kit data sheet ________________________________________________________________ Maxim Integrated Products 1 For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. Evaluates: MAX1775 General Description The MAX1775 evaluation kit (EV kit) is a fully assembled and tested surface-mount circuit board that contains a dual step-down switching regulator circuit. The circuit is configured for a main output voltage of +3.3V and a core output voltage of +1.8V. The main output provides up to 1.5A, and the core provides up to 500mA of current. Power for the circuit can be provided from a +2.7V to +5.5V DC source. The EV kit can be reconfigured for input voltages up to +28V. The core’s input can be powered from the input source or, for higher input voltages, from the main output. The MAX1775 EV kit demonstrates low quiescent current and high efficiency up to 95% for maximum battery life. Operation up to 1.25MHz allows the use of tiny surface-mount components. Evaluates: MAX1775 MAX1775 Evaluation Kit Component Suppliers PHONE FAX AVX SUPPLIER 803-946-0690 803-626-3123 Dale-Vishay 402-564-3131 402-563-6418 Fairchild 408-822-2000 408-822-2102 Nihon USA 661-867-2555 661-867-2698 Sanyo USA 619-661-6835 619-661-1055 Sprague-Vishay 603-224-1961 603-224-1430 Sumida 847-956-0666 847-956-0702 Taiyo Yuden 408-573-4150 408-573-4159 Note: Please indicate that you are using the MAX1775 when contacting these component suppliers. Quick Start The MAX1775 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. The step-down switching regulator main output voltage can be adjusted from +2.5V to +5.5V, and the core output voltage can be adjusted from +1V to +5V with resistors. Jumper Selection Shutdown Mode (Main Output) The MAX1775 EV kit features a shutdown mode that reduces the MAX1775 shutdown current to <5µA (typ), which preserves battery life. The 3-pin jumper, JU1, selects the shutdown mode for the MAX1775 main output (VMAIN). Table 1 lists the selectable jumper options. Table 1. Jumper JU1 Functions SHUNT LOCATION SHDNM PIN MAX1775 OUTPUT 1 and 2 Connected to VBATT MAX1775 enabled, VMAIN = +3.3V 2 and 3 Connected to GND Shutdown mode, VMAIN = 0 Outputs 1) Verify that shunts JU1 (SHDNM) and JU2 (SHDNC) are across pins 1 and 2. 2) Connect a voltmeter to the VMAIN pad. 3) Connect a +2.7V to +5.5V DC power supply to the VBATT pad. Connect the supply ground to the GND pad. 4) Turn on the power supply and verify that the main output (VMAIN) is +3.3V. 5) Verify that the core output (VCORE) is +1.8V. For instructions on selecting the feedback resistors for other output voltages, refer to the Evaluating Other Output Voltages section. Detailed Description The MAX1775 EV kit contains a dual step-down switching regulator. A +3.3V main output provides up to 1.5A, and a +1.8V core output provides up to 500mA of current. The EV kit operates from a +2.7V to +5.5V input voltage range. The EV kit can be reconfigured for input voltages up to +28V refer to the Evaluating High Input Voltage Operation section. The MAX1775 EV kit features several jumper-selectable options. Shutdown mode jumpers that reduce the MAX1775 shutdown current to <5µA (typ) are provided for the main and core outputs. Another option enables the main output (VMAIN) or an external voltage source to feed power to the core input. 2 Shutdown Mode (Core Output) The MAX1775 EV kit features a core shutdown mode that reduces the MAX1775 shutdown current, which preserves battery life. The 3-pin jumper, JU2, selects the shutdown mode for the MAX1775 core output (VCORE). Table 2 lists the selectable jumper options. Table 2. Jumper JU2 Functions SHUNT LOCATION SHDNC PIN MAX1775 OUTPUT 1 and 2 Connected to CVL CORE output enabled, VCORE = +1.8V 2 and 3 Connected to GND Shutdown mode, VCORE = 0 Core Input Supply The MAX1775 EV kit features an option that allows the main output voltage source to power the core’s input. Jumper JU3 selects which voltage source feeds the core’s input. Table 3 lists the jumper options. _______________________________________________________________________________________ MAX1775 Evaluation Kit PIN-HOLE TRACE INC PIN OPERATING MODE 1 and 2 (PC trace shorts 1 and 2) Connected to VBATT VBATT voltage source feeds core input Short 2 and 3 (Cut open trace across pin holes 1 and 2) Connected to VMAIN (core cascaded) VMAIN voltage source feeds core input Evaluating Other Output Voltages Evaluating High Input Voltage Operation Core Input The MAX1775 EV kit is factory-set for both step-down switching regulators, deriving their power from the input voltage (VBATT). The input to the core regulator is limited to +5V. A cascaded configuration must be used for input voltages greater than +5V. (The core converter derives its power from the main output voltage.) To configure the MAX1775 EV kit cascaded, cut open the PC board trace, shorting pinholes 1 and 2 at jumper JU3. Place a short (soldered jumper wire) across pinholes 2 and 3 at jumper JU3. Consult Table 3 for input voltage jumper selection. MAIN Output The MAX1775 EV kit’s step-down switching regulator main output (VMAIN) is set to +3.3V by feedback resistors (R4, R5). To generate output voltages other than +3.3V (+2.5V to +5V), select different voltage-divider resistors (R4, R5). Refer to the Setting the Output Voltages section in the MAX1775 data sheet for instructions on selecting the resistors. CORE Output The MAX1775 EV kit’s step-down switching regulator core output (VCORE) is set to +1.8V by feedback resistors (R1, R2). To generate output voltages other than +1.8V (+1V to +5V), select different voltage-divider resistors (R1, R2). Refer to the Setting the Output Voltages section in the MAX1775 data sheet for instructions on selecting the resistors. _______________________________________________________________________________________ 3 Evaluates: MAX1775 Table 3. Jumper JU3 Functions 4 VMAIN CS+ JU4 +2.7V TO +5.5V VBATT 3 2 1 VBATT SHDNC CVL SHDNM C10 OPEN C9 OPEN GND VBATT R5 40.2kΩ R4 66.5kΩ 1% 3 1 2 3 1 2 C1 10µF 25V JU2 JU1 C2 1µF 9 2 1 10 C6 0.22µF C5 1µF 5 8 6 SHDNC 4 7 PGND 3 GND FBC LXC INC CS- 13 16 15 12 CS+ 11 NDRV PDRV 14 FBM REF U1 MAX1775 SHDNM CVL CVH IN C7 10µF 6.3V P1-A P1-B R2 30.1kΩ 1% R1 24.3kΩ 1% L2 5.4µH JU3 D1 OPEN 3 2 1 L1 5.0µH C8 10µF 6.3V C4 47µF 6.3V GND VCORE VMAIN VBATT R3 33mΩ 1% 0.5W +1.8V CS+ C3 47µF 6.3V GND VMAIN +3.3V VMAIN Evaluates: MAX1775 MAX1775 Evaluation Kit Figure 1. MAX1775 EV Kit Schematic _______________________________________________________________________________________ MAX1775 Evaluation Kit Evaluates: MAX1775 1.0" 1.0" Figure 2. MAX1775 EV Kit Component Placement Guide— Component Side Figure 3. MAX1775 EV Kit PC Board Layout—Component Side 1.0" Figure 4. MAX1775 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. 5 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.