MAX770 Evaluation Kit The MAX770 EV kit comes with a MAX770CSA IC, but it can also evaluate the 12V-output MAX771 or 15V-output MAX772—simply order a free sample of the MAX771CSA or MAX772CSA to substitute for the MAX770CSA. ____________________Component List DESIGNATION QTY C1 1 C2 C3, C4 D1 J1 L1 1 ____________________________Features ♦ 5V or Adjustable Output Voltage ♦ 2.7V to 5.5V Input Range ♦ Up to 1A Output Current ♦ 5µA Max Shutdown Current ♦ 110µA Max Supply Current ♦ 300kHz Switching Frequency ♦ 8-Pin SO, Surface-Mount Construction ♦ Fully Assembled and Tested ______________Ordering Information PART TEMP. RANGE MAX770EVKIT-SO 0°C to +70°C PIN-PACKAGE Surface Mount DESCRIPTION 150µF, 10V low-ESR tantalum capacitor Sprague 595D157X0010D7 AVX TPSE227M010R0100 330µF, 10V low-ESR tantalum capacitor Sprague 595D337X001047 AVX TPSE337M006R0100 2 0.1µF, 50V ceramic capacitors 1 Schottky diode 1N5820 or Nihon NSQ03A02 (BV = 20V, IMAX = 3A) ______________Component Suppliers SUPPLIER PHONE FAX AVX (803) 946-0690 (800) 282-4975 (803) 626-3123 Coilcraft (847) 639-6400 (847) 639-1469 Coiltronics (561) 241-7876 (561) 241-9339 Dale (605) 668-4131 (605) 665-1627 IRC (512) 992-7900 (512) 992-3377 Matsuo (714) 969-2491 (714) 960-6492 Motorola (602) 303-5454 (602) 994-6430 Nihon (805) 867-2555 (805) 867-2698 1 3-pin header Siliconix (408) 988-8000 (800) 554-5565 (408) 970-3950 1 22µH power inductor Sumida CDR125-220 (ISAT = 2.3A, RSERIES = 50mΩ) Sprague (603) 224-1961 (603) 224-1430 Sumida (847) 956-0666 (847) 956-0702 N1 1 N-channel FET Motorola MTD20N03HDL (BV = 30V, RDS(ON) = 40mΩ @ VGS = 5V) R1 1 0.075Ω resistor (low inductance) IRC LR2010-01-R075-F or Dale WSL-2512-01-R075-F R2, R3 0 Open U1 1 MAX770CSA (8-pin SO) None 1 Shunt None 1 PC board None 1 MAX770 data sheet ________________________________________________________________ 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: MAX770 _______________General Description The MAX770 evaluation kit (EV kit) provides a regulated 5V output voltage from a 3V input source. It drives loads up to 1A with greater than 80% conversion efficiency. This EV kit is a fully assembled and tested surfacemount circuit board. Additional pads on the bottom of the board accommodate the external feedback resistors for setting different output voltages. Evaluates: MAX770 MAX770 Evaluation Kit _________________________Quick Start Inductor Selection The 22µH Sumida CDR125-220 inductor that comes mounted on the EV kit board is a low-resistance, shielded, medium-current inductor. It provides excellent performance over the line and load ranges of the MAX770/MAX771/MAX772. Refer to the section Choosing an Inductor in the MAX770/MAX771/MAX772 data sheet for instructions on selecting the inductor value. The MAX770 EV kit is a fully assembled and tested surface-mount printed circuit board. Follow these steps to verify board operation. Do not turn on the power supply until all connections are completed. 1) Connect a 2.7V to 5.5V supply to the pad marked V+ The ground connects to the GND pad. 2) Connect a voltmeter and load (if any) to the VOUT pad. 3) Place the shunt on J1 across pins 1 and 2, for normal operation. 4) Turn on the power and verify that the output voltage is 5.0V. 5) Refer to the sections Evaluating the MAX771/772 and Other Output Voltages to modify the board for different output voltages. Evaluating the MAX771/MAX772 The MAX770 can be replaced by a MAX771 to generate a 12V output voltage with up to 0.5A output current, or by a MAX772 to generate a 15V output voltage with up to 0.4A output current. Besides replacing the IC, the only other modification required is to use a low-ESR output capacitor with a voltage rating of 20V or greater. _______________Detailed Description Other Output Voltages Jumper Selection The MAX770, MAX771 and MAX772 are preset for 5V, 12V, and 15V output voltages, respectively. However, their outputs may also be adjusted via an external voltage divider formed by R2 and R3 (located on the bottom of the board). The only other modification required is to cut the trace across R3. The Output Voltage Selection section of the MAX770/MAX771/ MAX772 data sheet gives instructions for calculating R2 and R3 values. For input or output voltages greater than 10V, replace the 10V, C1 and C2 with higher voltage rating capacitors. The 3-pin header J1 selects shutdown mode. Table 1 lists the selectable jumper options. Table 1. Jumper J1 Functions SHUNT LOCATION SHDN PIN 2&3 Connected to V+ 1&2 Connected to GND MAX770 OUTPUT Shutdown mode, VOUT = V+ - 0.4V MAX770 enabled, VOUT = 5.0V 2.7V TO 5.5V V+ C1 150µF 10V SHDN 3 2 1 L1 22µH D1 NSQ03A02 VOUT MTD20N03HDL J1 4 5 C3 0.1µF 3 7 SHDN REF FB GND EXT CS+ MAX770 V+ AGND 1 N1 8 2 6 C4 0.1µF R1 0.075Ω C2 330µF 10V GND Figure 1. MAX770 EV Kit Schematic Diagram 2 _______________________________________________________________________________________ R2 OPEN R3 0Ω (SHORT) MAX770 Evaluation Kit Evaluates: MAX770 Figure 2. MAX770 EV Kit Component Placement Guide— Component Side Figure 3. MAX770 EV Kit Component Placement Guide— Solder Side Figure 4. MAX770 EV Kit PC Board Layout—Component Side Figure 5. MAX770 EV Kit PC Board Layout—Solder Side _______________________________________________________________________________________ 3 Evaluates: MAX770 MAX770 Evaluation Kit 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 © 1997 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.