MAX887 Evaluation Kit ____________________Component List DESIGNATION QTY DESCRIPTION C1, C2 2 C3 1 0.33µF ceramic capacitor C4 1 2.2µF, 20V tantalum capacitor Sprague 595D225X0020A2T C5 1 0.047µF ceramic capacitor C6 1 100pF ceramic capacitor C7 0 Open D1 1 Schottky diode Motorola MBRS130T3 Nihon EC10QS02 JU1, JU2 2 3-pin headers L1 1 33µH inductor Sumida CD54-330 R1 1 165kΩ, 1% resistor R2 1 100kΩ, 1% resistor U1 1 MAX887HESA None 2 Shunts None 1 MAX887 PC board None 1 MAX887 data sheet AVX Coilcraft Motorola Nihon Sprague Sumida Vishay/Vitramon (803) 946-0690 (800) 282-4975 (847) 639-6400 (602) 303-5454 (805) 867-2555 (603) 224-1961 (847) 956-0666 (203) 268-6261 ♦ 600mA Output Current ♦ Efficiency = 93%, VIN = 5V, VOUT = 3.3V @ IOUT = 0.2A ♦ Low Dropout Voltage ♦ 100% Max Duty Cycle ♦ Internal MOSFET ♦ Internal Synchronous Rectifier ♦ 5µA Max Shutdown Current ♦ 300kHz Switching Frequency ♦ Fully Assembled and Tested ______________Ordering Information PART MAX887EVKIT-SO TEMP. RANGE 0°C to +70°C BOARD TYPE Surface Mount _________________________Quick Start ______________Component Suppliers PHONE ♦ 3.3V Output Voltage ♦ 8-Pin SO, Surface-Mount Construction 47µF, 16V tantalum capacitors AVX TPSD47M016R0150 Sprague 593D476X0016D2W SUPPLIER ____________________________Features FAX The MAX887 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) Connect a +5V supply voltage to the VIN pad. The ground connects to the GND pad. 2) Connect a voltmeter and load, if any, to the VOUT pad. 3) For normal operation, place the shunt on JU1 across pins 2 and 3. 4) Turn on the power supply to the board, and verify that the output voltage is 3.3V. (To select other output voltages, refer to the Output Voltage Selection section in the MAX887 data sheet for instructions on selecting feedback resistors R1 and R2.) (803) 626-3123 (847) 639-1469 (602) 994-6430 (805) 867-2698 (603) 224-1430 (847) 956-0702 (203) 452-5670 ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 Evaluates: MAX887 _______________General Description The MAX887 evaluation kit (EV kit) provides a 3.3V output voltage from a +3.5V to +11V input. It delivers up to 600mA and operates with up to 100% duty cycle for low dropout voltage. Typical efficiencies are 93%. The MAX887 features a low-current (2.5µA typ) shutdown mode, as well as current-mode operation for superior load and line response. Cycle-by-cycle current limiting protects the internal MOSFET and rectifier. This EV kit is a fully assembled and tested surfacemount circuit board. It can be used to evaluate other output voltages by changing feedback resistors R1 and R2. Evaluates: MAX887 MAX887 Evaluation Kit VIN C1 47µF 16V 3.5V TO 11V JU1 2 1 VL JU2 SYNC 8 3 1 SHDN C3 0.33µF V+ SHDN LX L1 33µH 7 U1 D1 MBRS130 MAX887 3 6 2 1 GND SYNC 5 VOUT 3.3V C2 47µF 16V C6 100pF R1 165k 1% 4 VL VL FB 2 REF C4 2.2µF 20V C7 OPEN 3 R2 100k 1% VOUT = (1 + R1/R2) x 1.25V C5 0.047µF Figure 1. MAX887 EV Kit Schematic _______________Detailed Description The MAX887 provides a 3.3V output from a +3.5V to +11V input voltage. It delivers up to 500mA, and operates with up to 100% duty cycle for low dropout voltage. Other output voltages can be programmed by changing feedback resistor R1. R1 is given by the following equation: V R1 = R2 OUT − 1 VFB where R2 = 100k and VFB = 1.25V The 3-pin header JU1 selects shutdown mode. Table 1 lists the selectable jumper options. In shutdown, the internal switching MOSFET and synchronous rectifier turn off and the output voltage falls to 0V. Connect the SHDN pin to VIN for normal operation. The 3-pin header JU2 selects synchronization mode. Table 2 lists the selectable jumper options. To avoid RF interference with sensitive IF and dataacquisition circuits, a SYNC pad is provided on the board for synchronization to an external clock. When SYNC is connected to GND, Idle Mode™ operation is enabled and the MAX887 is placed in PFM mode at light loads. PFM Idle Mode is a trademark of Maxim Integrated Products. 2 operation improves efficiency and reduces quiescent current typically to 200µA. When SYNC is connected to VL, forced PWM operation is enabled. PWM operation reduces noise in sensitive communications applications. Refer to the Forced PWM and Idle Mode Operation section in the MAX887 data sheet for more information. Table 1. Jumper JU1 Functions SHUNT LOCATION SHDN PIN 1&2 Connected to GND Shutdown mode, VOUT = 0V 2&3 Connected to VIN MAX887 enabled, VOUT = 3.3V MAX887 OUTPUT Table 2. Jumper JU2 Functions SHUNT LOCATION SYNC PIN OPERATING MODE 1&2 Connected to GND Idle mode, PFM; IQUIESCENT = 200µA 2&3 Connected to VL Low-noise, fixed-frequency PWM operation; IQUIESCENT = 2.7mA Open Connected to an Synchronization to an external SYNC pad external clock _______________________________________________________________________________________ MAX887 Evaluation Kit Evaluates: MAX887 Figure 2. MAX887 EV Kit Component Placement Guide— Component Side Figure 3. MAX887 EV Kit PC Board Layout—Component Side Figure 4. MAX887 PC Board Layout—Solder Side _______________________________________________________________________________________ 3 Evaluates: MAX887 MAX887 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 © 1996 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.