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| 19-1436; Rev 1; 9/99 MAX1623 Evaluation Kit _____________General Description The MAX1623 evaluation kit (EV kit) provides a preset 3.3V output voltage from a +4.5V to +5.5V input source. It delivers up to 3A output current with greater than 90% efficiency. The MAX1623 is a step-down switching regulator with synchronous rectification that includes two low-onresistance 0.1 (max), 3A MOSFET power switches. It features a resistor-programmable fixed off-time as well as current-mode operation for superior load- and linetransient response. The MAX1623 EV kit can also be used to evaluate other output voltages besides 3.3V by changing RTOFF and the feedback resistors R1 and R2 located on the bottom of the board. ____________________________Features o +4.5V to +5.5V Input Voltage Range o Output Voltage 3.3V Preset 1.1V to 3.8V Adjustable (optional resistor-divider) o Guaranteed 3A Output Current o 94% Efficiency (VIN = 5V, VOUT = 3.3V at IOUT = 2A) o Internal 3A, 0.1 (max) MOSFET Switches o Up to 350kHz Switching Frequency o Thermal Shutdown at Tj = +145C o Surface-Mount Construction o Fully Assembled and Tested Evaluates: MAX1623 Component List DESIGNATION QTY C1 1 DESCRIPTION 220F, 10V, low-ESR tantalum cap Sprague 593D227X0010E2W or AVX TPSE227M010R0100 330F, 10V, low-ESR tantalum cap Kemet T510X337M010AS 470pF ceramic capacitor 0.47F ceramic capacitor 4.7F, 16V tantalum capacitor Sprague 595D475X0016A2B Not installed 4.7F, 10V X5R ceramic capacitor Taiyo Yuden LMK316BJ475ML 4.7H power inductor Sumida CDRH125-4R4 or Coiltronics UP2-4R7 110k, 1% resistor Not installed 10, 5% resistor MAX1623EAP (SSOP-20) Shunts 3-pin headers MAX1623 PC board MAX1623 data sheet SUPPLIER AVX Coiltronics Dale-Vishay Kemet Motorola Sprague Sumida Taiyo Yuden PART MAX1623EVKIT Ordering Information TEMP. RANGE 0C to +70C IC PACKAGE 20 SSOP C2 C3 C4 C5 C6, C7 C8 1 1 1 1 0 1 Component Suppliers PHONE 803-946-0690 561-241-7876 402-564-3131 408-986-0424 602-303-5454 603-224-1961 708-956-0666 408-573-4150 FAX 803-626-3123 561-241-9339 402-563-6418 408-986-1442 602-994-6430 603-224-1430 708-956-0702 408-573-4159 L1 RTOFF R1, R2 R3 U1 None JU1, JU2 None None 1 1 0 1 1 2 2 1 1 Note: Please indicate that you are using the MAX1623 when contacting these component suppliers. ________________________________________________________________ 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 1-800-835-8769. MAX1623 Evaluation Kit Evaluates: MAX1623 _________________________Quick Start The MAX1623 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, 3A supply to the VIN pad. Connect ground to the GND pad. 2) Connect a voltmeter and load, if any, to the VOUT pad. 3) Verify that the shunt is across JU1 pins 2 and 3 for normal operation. 4) Turn on the power supply to the board. Verify that the output voltage is 3.3V. 5) To select other output voltages, refer to the Setting the Output Voltage section in the MAX1623 data sheet for instructions on selecting feedback resistors R1 and R2. Other Output Voltages The MAX1623 EV kit is preset for a 3.3V output voltage. However, the output voltage may also be adjusted by an external voltage divider formed by R1 and R2 (located on the bottom of the board). In addition, RTOFF must be changed to obtain the desired switching frequency (see Switching Frequency and Programming the OffTime in the MAX1623 data sheet). The only other modifications required are to cut the trace across R1 and remove the shunt from JU2. Refer to the Setting the Output Voltage and Output Filter Capacitor sections in the MAX1623 data sheet for instructions on selecting feedback resistors R1 and R2 and output capacitor values. PC Board Thermal Resistance Junction to ambient thermal resistance greatly depends on the amount of copper area immediately surrounding the IC's leads. This EV kit has 0.85 in.2 of copper area and has a measured thermal resistance of 45C/W. _______________Detailed Description The MAX1623 EV kit provides a preset 3.3V output from a +4.5V to +5.5V input voltage. It delivers up to 3A of output current. Table 1. Jumper JU1 Functions (Shutdown Mode) SHUNT LOCATION 2&3 SHDN PIN MAX1623 OUTPUT MAX1623 enabled, VOUT = 3.3V Shutdown mode, VOUT = 0 Table 2. Jumper JU2 Functions (FB Selection) SHUNT LOCATION 1&2 Not installed 2&3 FBSEL PIN Connected to VIN Floating Connected to GND MAX1623 OUTPUT VOUT = 2.5V VOUT = 3.3V Adjustable mode Connected to VIN 1&2 Connected to GND 2 _______________________________________________________________________________________ MAX1623 Evaluation Kit Evaluates: MAX1623 VIN 4.5V to 5.5V C6 OPEN C1 220F 10V R3 10 C5 C8 4.7F 10V 2 4 6 IN IN IN VCC SHDN VIN JU1 3 2 1 4.7F 16V RTOFF 110k, 1% 14 7 SHDN U1 MAX1623 LX LX LX LX LX LX 1 3 5 20 18 16 L1 4.7H VOUT 3.3V C7 OPEN C2 330F 10V 9 8 TOFF FBSEL REF 12 GND 11 15 PGND 17 PGND 19 PGND FB COMP 10 R2 OPEN R1 SHORT (PC TRACE) VIN 1 JU2 2 3 C4 0.47F 13 C3 470pF VOUT = 1.10V 1 + R1 R2 ( ) NOTE: HEAVY LINES DENOTE HIGH SWITCHING CURRENT PATHS. TIE GND TO PGND AT A SINGLE LOCATION. SHUNT LOCATION JU2 pins 1, 2 JU2 Not installed (default) JU2 pins 2, 3 FBSEL PIN Connected to VIN Floating MAX1623 OUTPUT 2.5V 3.3V Adjustable output. Cut trace between R1 pads. Refer to MAX1623 data sheet for R1 and R2 values. RTOFF (k) (for 300kHz) 180 110 Connected to GND 270 Figure 1. MAX1623 EV Kit Schematic _______________________________________________________________________________________ 3 MAX1623 Evaluation Kit Evaluates: MAX1623 1.0" 1.0" Figure 2. MAX1623 EV Kit Component Placement Guide-- Component Side Figure 3. MAX1623 EV Kit Component Placement Guide-- Solder Side 1.0" 1.0" Figure 4. MAX1623 EV Kit PC Board Layout--Component Side Figure 5. MAX1623 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) 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. |
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