MAX1790EVKIT

19-1563; Rev 0a; 1/00 MAX1790 Evaluation Kit Features ♦ +2.6V to +5V Input Voltage Range ♦ 5V Output Voltage ♦ Up to 500mA Output Current ♦ 640kHz Fixed-Frequency PWM Operation ♦ Internal MOSFET Switch ♦ 0.1µA IC Shutdown Current ♦ Surface-Mount Components ♦ Fully Assembled and Tested Ordering Information Component List DESIGNATION QTY DESCRIPTION C1 1 33µF, 10V, low-ESR electrolytic cap (POSCAP) Sanyo 10TPA33M C2 1 47µF, 6.3V, low-ESR electrolytic cap (POSCAP) Sanyo 6TPA47M PART TEMP. RANGE MAX1790EVKIT 0°C to +70°C IC PACKAGE 8 µMAX Component Suppliers SUPPLIER PHONE FAX 708-639-6400 708-639-1469 847-843-2798 C3 1 0.033µF ceramic capacitor (1206) Coilcraft C4 1 820pF ceramic capacitor (1206) Nihon 847-843-7500 0.22µF ceramic capacitor (1206) Sumida 408-982-9660 408-982-9858 81-3-5952-8533 81-3-5952-8690 C5 1 C6 1 56pF ceramic capacitor (0805) Sumitomo C7 1 0.1µF ceramic capacitor (0805) Toshiba 949-455-2000 949-859-3963 516-543-7100 516-864-7630 1 5.4µH, 1.6A inductor Sumida CDRH5D18-5R4NC or Sumitomo CXLM120-5R6 Zetex L1 D1 1 1A Schottky diode Nihon EP10QY03 or Toshiba CRS02 Note: Please indicate that you are using the MAX1790 when contacting these component suppliers. Quick Start R3 1 62kΩ ±5% resistor (1206) U1 1 MAX1790EUA (8-pin µMAX) The MAX1790 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 +2.6V to +5V supply to the VIN pad. Connect ground to the GND pad. None 1 Shunt 2) Connect a voltmeter to the VOUT pad. None 1 MAX1790 PC board None 1 MAX1790 EV kit data sheet 3) Verify that the shunt is across JU1 pins 1 and 2 to enable the MAX1790. None 1 MAX1790 data sheet JU1 1 3-pin header R1 1 1MΩ ±1% resistor (1206) R2 1 324kΩ ±1% resistor (1206) 4) Turn on the power supply and verify that the output is at +5V. ________________________________________________________________ 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: MAX1790 General Description The MAX1790 evaluation kit (EV kit) is a fully assembled and tested surface-mount circuit board that contains a fixed-frequency, pulse-width-modulated (PWM), stepup DC-DC converter. The EV kit provides a +5V output voltage from an input as low as +2.6V. It delivers up to 500mA output current. The MAX1790 features an internal MOSFET switch, programmable soft-start, and fast transient response. The MAX1790 EV kit provides low quiescent current and high efficiency for maximum battery life. Operation at 640kHz allows the use of a tiny surface-mount inductor. Evaluates: MAX1790 MAX1790 Evaluation Kit Detailed Description Shutdown Mode The EV kit features a shutdown mode that reduces the MAX1790 quiescent current to 0.1µA, preserving battery life. The three-pin header, JU1, selects the shutdown mode (Table 1). Evaluating Other Output Voltages The EV kit output is programmed to 5V. However, the output voltage can also be adjusted from VIN to 12V by selecting R1 and R2 values. R2 can have a value up to 500kΩ without sacrificing accuracy. R1 is then given by: R1 = R2 [(VOUT / VFB) - 1] where VFB = 1.24V. Table 1. Jumper JU1 Functions SHUNT LOCATION SHDN PIN 1-2 Connected to VIN MAX1790 enabled, VOUT = +5V 2-3 Connected to GND Shutdown mode, VOUT = VIN - VDIODE MAX1790 OUTPUT Table 2. Frequency Pin Setting SHUNT LOCATION FREQUENCY PIN Installed Connected to VIN 1.2MHz Not installed Floating 640kHz Refer to the Application Circuits section of the MAX1790 data sheet for different output voltage circuits. Switching Frequency Selection The MAX1790 is shipped to operate at 640kHz. The switching frequency can be changed to 1.2MHz by installing jumper JU2 (Table 2). Refer to the MAX1790 data sheet for selecting the proper components to operate at 1.2MHz. 2 SWITCHING FREQUENCY _______________________________________________________________________________________ MAX1790 Evaluation Kit Evaluates: MAX1790 VIN C1 33µF 10V C5 0.22µF L1 5.4µH VIN 6 SHDN 1 2 JU1 3 3 IN LX SHDN C2 47µF 6.3V U1 VIN MAX1790 7 FREQ VOUT D1 5 GND C7 0.1µF 4 JU2 R1 1M 1% GND 8 C3 0.033µF SS FB 2 COMP R2 324k 1% 1 R3 62k GND C6 56pF C4 820pF Figure 1. MAX1790 EV Kit Schematic _______________________________________________________________________________________ 3 Evaluates: MAX1790 MAX1790 Evaluation Kit 1.0" Figure 2. MAX1790 EV Kit Component Placement Guide— Component Side 1.0" 1.0" Figure 3. MAX1790 EV Kit PC Board Layout—Component Side Figure 4. MAX1790 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. 4 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: Maxim Integrated: MAX1790EVKIT