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| 19-1563; Rev 0a; 1/00 MAX1790 Evaluation Kit 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. o +2.6V to +5V Input Voltage Range o 5V Output Voltage o Up to 500mA Output Current o 640kHz Fixed-Frequency PWM Operation o Internal MOSFET Switch o 0.1A IC Shutdown Current o Surface-Mount Components o Fully Assembled and Tested Features Evaluates: MAX1790 Component List DESIGNATION QTY C1 1 DESCRIPTION 33F, 10V, low-ESR electrolytic cap (POSCAP) Sanyo 10TPA33M 47F, 6.3V, low-ESR electrolytic cap (POSCAP) Sanyo 6TPA47M 0.033F ceramic capacitor (1206) 820pF ceramic capacitor (1206) 0.22F ceramic capacitor (1206) 56pF ceramic capacitor (0805) 0.1F ceramic capacitor (0805) 5.4H, 1.6A inductor Sumida CDRH5D18-5R4NC or Sumitomo CXLM120-5R6 1A Schottky diode Nihon EP10QY03 or Toshiba CRS02 3-pin header 1M 1% resistor (1206) 324k 1% resistor (1206) 62k 5% resistor (1206) MAX1790EUA (8-pin MAX) Shunt MAX1790 PC board MAX1790 EV kit data sheet MAX1790 data sheet PART MAX1790EVKIT Ordering Information TEMP. RANGE 0C to +70C IC PACKAGE 8 MAX Component Suppliers SUPPLIER Coilcraft Nihon Sumida Sumitomo Toshiba Zetex PHONE 708-639-6400 847-843-7500 408-982-9660 81-3-5952-8533 949-455-2000 516-543-7100 FAX 708-639-1469 847-843-2798 408-982-9858 81-3-5952-8690 949-859-3963 516-864-7630 C2 C3 C4 C5 C6 C7 L1 1 1 1 1 1 1 1 Note: Please indicate that you are using the MAX1790 when contacting these component suppliers. D1 JU1 R1 R2 R3 U1 None None None None 1 1 1 1 1 1 1 1 1 1 Quick Start 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. 2) Connect a voltmeter to the VOUT pad. 3) Verify that the shunt is across JU1 pins 1 and 2 to enable the MAX1790. 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. MAX1790 Evaluation Kit Evaluates: MAX1790 Detailed Description Shutdown Mode The EV kit features a shutdown mode that reduces the MAX1790 quiescent current to 0.1A, preserving battery life. The three-pin header, JU1, selects the shutdown mode (Table 1). Table 1. Jumper JU1 Functions SHUNT LOCATION 1-2 2-3 SHDN PIN Connected to VIN Connected to GND MAX1790 OUTPUT MAX1790 enabled, VOUT = +5V Shutdown mode, VOUT = VIN - VDIODE 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 500k without sacrificing accuracy. R1 is then given by: R1 = R2 [(VOUT / VFB) - 1] where VFB = 1.24V. Refer to the Application Circuits section of the MAX1790 data sheet for different output voltage circuits. Table 2. Frequency Pin Setting SHUNT LOCATION Installed Not installed FREQUENCY PIN Connected to VIN Floating SWITCHING FREQUENCY 1.2MHz 640kHz 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 _______________________________________________________________________________________ MAX1790 Evaluation Kit Evaluates: MAX1790 VIN C5 0.22F VIN 6 SHDN 1 2 3 L1 5.4H C1 33F 10V JU1 VIN 3 IN SHDN LX 5 D1 VOUT C2 47F 6.3V C7 0.1F U1 MAX1790 7 JU2 FREQ GND 4 GND 8 2 R1 1M 1% GND SS COMP 1 FB C3 0.033F R2 324k 1% R3 62k C6 56pF C4 820pF Figure 1. MAX1790 EV Kit Schematic _______________________________________________________________________________________ 3 MAX1790 Evaluation Kit Evaluates: MAX1790 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 (c) 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. |
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