19-1381; Rev 0; 7/98 MAX1678 Evaluation Kit Features ♦ 0.87V to VOUT Input Range ♦ Synchronous Rectified—No External Diode Required ♦ 3.3V Output Voltage (or Adjustable) ♦ 100mA Output ♦ 90% Efficiency ♦ 2µA Shutdown Current ♦ Small Surface-Mount Components Component List DESIGNATION QTY DESCRIPTION 2 10µF, 10V ceramic capacitor Taiyo Yuden LMK325BJ106MN, TDK C3225X5R1A106M L1 1 47µH, 240mA power inductor Coilcraft DS1608C-473 Sumida CD43-470 Murata LQH4N470K J1 1 3-pin jumper J2 1 2-pin jumper R1, R4 2 1MΩ, 1% resistors R2, R3 2 Open R5 1 100kΩ , 5% resistor U1 1 MAX1678EUA None 2 Shunts None 1 MAX1678 EV kit PC board None 1 MAX1678 data sheet C1, C2 ♦ Inductor Damping Switch Suppresses EMI Ordering Information PART MAX1678EVKIT TEMP. RANGE 0°C to +70°C IC PACKAGE 8 µMAX _________________________Quick Start The MAX1678 EV kit is shipped 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 that the shunts are positioned on the jumpers as listed in Table 2 for a 3.3V output. 2) Connect a +0.87V to +3.3V supply voltage to the VIN pad. Connect ground to the GND pad. Note: once started, the input voltage may drop as low as 0.7V if the output current is less than 10mA. 3) Connect a voltmeter and the load (if any) to the VOUT pad. Component Suppliers PHONE FAX Coilcraft SUPPLIER 847-639-6400 847-639-1469 Coiltronics 561-241-7876 561-241-9339 Murata 814-237-1431 814-238-0490 Sumida 847-956-0666 847-956-0702 Taiyo Yuden 408-573-4150 408-573-4159 TDK 847-390-4373 847-390-4428 4) Turn on the power and verify that the output voltage is +3.3V. ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 408-737-7600 ext. 3468. Evaluates: MAX1678 General Description The MAX1678 evaluation kit (EV kit) provides a regulated 3.3V output while operating on input voltages as low as 0.7V with guaranteed start-up at 0.87V. The input source can be a 1 or 2-cell battery or a DC supply. Efficiency is typically 90% with output loads up to 100mA. The kit uses surface-mount components and is fully assembled and tested for quick evaluation. Jumpers are provided for selecting an adjustable output voltage and for shutdown control. Evaluates: MAX1678 MAX1678 Evaluation Kit Detailed Description Component Selection The final circuit performance is determined by the quality of the components surrounding the MAX1678. The input and output capacitors must have low equivalent-seriesresistance (ESR) to handle the high peak currents found in switching regulators. Low ESR is especially critical in low-voltage circuits to reduce the output ripple. Ceramic capacitors are supplied on the MAX1678 EV kit because of their small size and low ESR in the value range needed for the circuit. Jumper Selections Two jumpers on the PC board allow selection of several configurations. Table 1 lists the jumper functions. Table 2 lists the jumper positions when setting the board for 3.3V operation. Table 1. Jumper Functions JUMPER SHUNT POSITION PIN CONNECTION MAX1678 OPERATION J1 1&2 SHDN connected to BATT The MAX1678 is enabled. J1 2&3 SHDN connected to GND The MAX1678 is disabled. J1 Open SHDN not controlled by the board SHDN must be driven by a signal connected to the SHDN pad. J2 Shorted FB pin connected to GND VOUT is preset to 3.3V. J2 Open FB pin connected to the resistor-divider A resistor must be installed in R3 to set the output voltage. See the MAX1678 data sheet for more information. Table 2. Jumper Positions for Normal 3.3V Operation JUMPER SHUNT POSITION J1 1&2 J2 Shorted PIN CONNECTION MAX1678 OPERATION SHDN pin connected to BATT The MAX1678 is enabled. FB pin connected to GND VOUT is preset to 3.3V. L1 47µH 1 BATT J1 SHDN C1 10µF 1 2 3 4 BATT LX SHDN OUT 7 8 OUT U1 R1 1M 1% R3 OPEN MAX1678 2 PFI FB GND R5 100k 5 R2 OPEN J2 6 GND PFO C2 10µF 3 Figure 1. MAX1678 EV Kit Schematic 2 GND R4 1M 1% _______________________________________________________________________________________ PFO MAX1678 Evaluation Kit Evaluates: MAX1678 1.0" Figure 2. Component Placement Guide—Component Side 1.0" 1.0" Figure 3. PC Board Layout—Component Side Figure 4. PC Board Layout—Solder Side _______________________________________________________________________________________ 3 Evaluates: MAX1678 MAX1678 Evaluation Kit NOTES 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. 4 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.