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| 19-1793; Rev 0; 8/00 MAX1734 Evaluation Kit General Description The MAX1734 evaluation kit (EV kit) is a fully assembled and tested surface-mount PC board that contains a switching-regulator circuit configured for a +1.8V output. At up to 250mA, it accepts inputs from a +2.7VDC to +5.5VDC source or a 1-cell lithium-ion (Li+) or 2- to 3-cell battery. The MAX1734 features an internal P-channel MOSFET switch, a synchronous rectifier, logic-controlled shutdown, and digital soft-start to limit startup current. The MAX1734 EV kit provides low quiescent current and efficiency up to 93%, providing maximum battery life. High-frequency operation up to 1.2MHz with a maximum duty cycle of 100% allows the use of tiny surfacemount components. The EV kit can also evaluate the MAX1733 after modifications. o +2.7V to +5.5V Battery Input Voltage o +1.8V Output Voltage o 250mA Output Current o Efficiency >85% from 2mA to 250mA o Internal P-Channel Switch and Synchronous Rectifier o 0.01A (typ) IC Shutdown Current o 50A Quiescent Supply Current o Up to 1.2MHz (max) Switching Frequency o Surface-Mount Components o Fully Assembled and Tested Features Evaluates: MAX1733/MAX1734 Component List DESIGNATION QTY C1 1 DESCRIPTION 2.2F, 10V X5R ceramic capacitor Taiyo Yuden LMK325BJ106MN or Taiyo Yuden LMK212BJ225MG 22F, 6.3V tantalum capacitor AVX TAJA226M006R 3-pin header 10H inductor Sumida CR43-100MC Not installed MAX1734EUK18 (5-pin SOT23, top mark ADKW) Shunt MAX1734 PC board MAX1734 data sheet MAX1734 EV kit manual PART MAX1734EVKIT Ordering Information TEMP. RANGE 0C to +70C IC PACKAGE 5 SOT23 C2 JU1 L1 R1, R2 U1 None None None None 1 1 1 0 1 1 1 1 1 Quick Start The MAX1734 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 +2.7V (for guaranteed startup) to +5.5V supply to the VIN pad. Connect the supply ground to the GND pad. 2) Connect a voltmeter to the VOUT pad. 3) Verify that the shunt is across pins 1 and 2 on JU1, thus enabling the MAX1734. 4) Turn on the power supply and verify that the output is at +1.8V. Component Suppliers SUPPLIER AVX Sumida USA Taiyo Yuden PHONE 803-946-0690 847-956-0666 408-573-4150 FAX 803-626-3123 847-956-0702 408-573-4159 For instructions on selecting the feedback resistors for other output voltages, see Evaluating Other Output Voltages. Detailed Description The MAX1734 EV kit contains a highly efficient switchingregulator circuit. The circuit provides a +1.8V output at 250mA from a +2.7V to +5.5V input voltage range. Digital soft-start limits current during startup. Note: Please indicate that you are using the MAX1734 when contacting these component suppliers. ________________________________________________________________ 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. MAX1734 Evaluation Kit Evaluates: MAX1733/MAX1734 Jumper Selection (Shutdown Mode) The MAX1734 EV kit features a shutdown mode that reduces the MAX1734 quiescent current below 5A (max), preserving battery life. The 3-pin header, JU1, selects the shutdown mode for the circuit. Table 1 lists the selectable jumper options. Table 1. Jumper JU1 Functions SHUNT LOCATION SHDN PIN MAX1734 OUTPUT MAX1734 enabled, VOUT = +1.8V Shutdown mode, VOUT = 0 1, 2 Connected to VIN Evaluating Other Output Voltages The output is set to +1.8V by shorting the feedback pin (FB/OUT) to VOUT. This is the default setting for the MAX1734 EV kit. To generate output voltages other than +1.8V (+1.25V to +2.0V), the MAX1734EUK18 must be replaced with a different output MAX1734 or the MAX1733EUK. When using a MAX1733, cut the PC board trace to the mounting pads of R1, and select the external voltage-divider resistors (R1, R2). Refer to the Setting the Output Voltage section in the MAX1733 data sheet for instructions on selecting R1 and R2. 2, 3 Connected to GND VIN 1 IN U1 LX 5 L1 10H VOUT R1 (SHORTED BY PC BOARD TRACE) 3 C1 2.2F 10V 1 JU1 3 GND 2 SHDN MAX1734 FB/OUT 4 C2 22F 6.3V GND GND 2 R2 OPEN SHDN Figure 1. MAX1734 EV Kit Schematic 2 _______________________________________________________________________________________ MAX1734 Evaluation Kit Evaluates: MAX1733/MAX1734 1.0" 1.0" Figure 2. MAX1734 EV Kit Component Placement Guide-- Component Side Figure 3. MAX1734 EV Kit Component Placement Guide-- Solder Side 1.0" 1.0" Figure 4. MAX1734 EV Kit PC Board Layout--Component Side Figure 5. MAX1734 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________3 (c) 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. |
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