19-1660; Rev 0; 8/00 MAX1760 Evaluation Kit The MAX1760 evaluation kit (EV kit) is a fully assembled and tested surface-mount circuit board that contains a boost switching-regulator circuit. The EV kit provides a regulated +3.3V output at up to 800mA of current. The input voltage range is +0.7V to +5.5V. However, the output voltage will rise above the regulation point for input voltages exceeding 3.3V. A one- or two-cell battery input can also be used to power the EV kit. The MAX1760 features an internal N-channel MOSFET switch, a synchronous rectifier, and a pin-selectable forced PWM mode. The MAX1760 EV kit demonstrates low quiescent current and power efficiency up to 96%, thus increasing battery life. Operation at 1MHz allows the use of tiny surface-mount components. Features ♦ +0.7V to +5.5V Input Voltage ♦ +3.3V Output Voltage ♦ Internal Synchronous Rectifier Provides up to 96% Efficiency ♦ Output is Adjustable with External Resistors ♦ Up to 800mA Output ♦ On-Chip N-Channel Switch ♦ 1µA Shutdown Current ♦ 1MHz Switching Frequency ♦ Fixed-Frequency PWM Operation ♦ Surface-Mount Components ♦ Fully Assembled and Tested Component List DESIGNATION QTY DESCRIPTION C1 1 33µF, 16V, low-ESR electrolytic cap Sanyo 16TPC33M C2 1 100µF, 6.3V, low-ESR electrolytic cap Sanyo 6TPC100M C3 1 1µF, 10V, X5R ceramic cap (0805) Taiyo Yuden LMK212BJ105MG C4 1 0.68µF, 10V, X5R ceramic cap (0805) Taiyo Yuden LMK212BJ684KG C5 1 0.22µF, 25V, X7R ceramic cap (1206) Taiyo Yuden TMK316BJ224KF C6 0 Not installed (0805) D1 1 Not installed, Nihon EP10QY03 L1 1 3.3µH, 1.4A inductor Coilcraft DO1606T-332 R3 1 4.7Ω ±5% resistor (0805) R1, R2, R4, R5 0 Not installed (0805) U1 1 Maxim MAX1760EUB (10-pin µMAX) JU1, JU2 2 3-pin headers None 2 Shunts (JU1, JU2) None 1 MAX1760 PC board None 1 MAX1760 data sheet None 1 MAX1760 EV kit data sheet Ordering Information PART TEMP. RANGE MAX1760EVKIT 0°C to +70°C IC PACKAGE 10 µMAX Component Suppliers PHONE FAX Coilcraft SUPPLIER 847-639-6400 847-639-1469 Nihon USA 661-867-2555 661-867-2698 Sanyo USA 619-661-6835 619-661-1055 Taiyo Yuden 408-573-4150 408-573-4159 Note: Please indicate that you are using the MAX1760 when contacting these component suppliers. Quick Start The MAX1760 EV kit is fully assembled and tested. Follow these steps to verify board operation for a +3.3V output. Do not turn on the power supply until all connections are completed. 1) Connect a +1.1V to +3.2V DC power supply to the VIN pad. Connect the supply ground to the GND pad. 2) Connect a voltmeter to the VOUT pad. 3) Verify that jumper JU1 (ON) has a shunt across pins 2 and 3 and jumper JU2 (CLK/SEL) has a shunt across pins 1 and 2. 4) Turn on the power supply and verify that the main output is +3.3V. ________________________________________________________________ Maxim Integrated Products 1 For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. Evaluates: MAX1760 General Description Evaluates: MAX1760 MAX1760 Evaluation Kit Table 1. Jumper JU1 Functions SHUNT LOCATION ON PIN 1-2 Connected to VOUT 2-3 Connected to GND MAX1760 OUTPUT Shutdown mode, VOUT = VIN - VDIODE MAX1760 enabled, VOUT = +3.3V Table 2. Jumper JU2 Functions SHUNT LOCATION CLK/SEL PIN 1-2 Connected to VOUT Forced PWM mode: PWM operation at all loads 2-3 Connected to GND Normal mode: PFM at light load and PWM at medium to heavy load None Clock connected to CLK/SEL pad PWM mode synchronized to external 500kHz to 1200kHz range clock Detailed Description The MAX1760 EV kit contains a boost switching-regulator circuit that provides a +3.3V output. The circuit requires a +0.7V to +3.2V input voltage to maintain regulation. The output supplies up to 800mA as configured. The output voltage can also be adjusted from +2.5V to +5.5V with external resistors. The MAX1760 EV kit permits jumper-selectable operational modes: normal mode, forced PWM mode, and forced PWM mode with the internal oscillator synchronized to an external clock. Jumper Selection Two PC board jumpers provide the user with various operating configurations. Shutdown mode and CLK/ SEL mode are configurable via jumpers. Shutdown Mode The MAX1760 EV kit features a shutdown mode that reduces the IC’s quiescent current to 1µA (typ), preserving battery life. The 3-pin jumper, JU1, selects the shutdown mode for the circuit. Table 1 lists the selectable jumper options. CLK/SEL Operating Mode Jumper JU2 controls the CLK/SEL pin operating mode. Options include low-noise forced PWM mode, normal mode, and an external clock source to drive the CLK/SEL pin. The external clock source must operate in the 500kHz to 1200kHz range. Table 2 lists the CLK/SEL jumper options. OPERATING MODE Evaluating Other Output Voltages The output is set to +3.3V by grounding the feedback pin (FB). To generate output voltages other than +3.3V (+2.5V to +5.5V), cut open the PC board trace shorting R2, and select the external voltage-divider resistors (R1, R2). Refer to the Setting the Output Voltage section in the MAX1760 data sheet for instructions on selecting R1 and R2. To maintain a regulated output, the input voltage range is +0.7V to VOUT to maintain a regulated output. Evaluating Other Current Limits The EV kit inductor current limit can be set from 625mA to 1250mA. The EV kit is factory-configured for 1250mA. To set the current limit to 625mA, cut open the PC board trace shorting R4, and insert 1MΩ resistors for R4 and R5. Refer to the Setting the Switch Current and Soft Start section of the MAX1760 data sheet to select other R4 and R5 values. Enabling Soft-Start The MAX1760 soft-start feature will limit inrush current during startup. Installing capacitor C6 activates this feature. Refer to the Setting the Switch Current and Soft-Start section in the MAX1760 data sheet for instructions on selecting C6 values. Evaluating Lower Startup Input Voltages The MAX1760 EV kit can operate from DC supply voltages down to +0.7V. Install Schottky diode, D1, to ensure startup when V IN is below +1.1V. Refer to the Output Diode section in the MAX1760 data sheet for instructions on selecting D1. D1 is not needed for input voltages above +1.1V. 2 _______________________________________________________________________________________ _______________________________________________________________________________________ VOUT GND CLK/SEL ON C1 33µF 16V 3 1 2 1 3 2 JU2 JU1 C5 0.22µF 25V R5 OPEN C6 OPEN R4 SHORT 1 2 6 10 PGND 7 3 FB OUT POUT LX GND ISET REF U1 MAX1760 CLK/SEL ON L1 3.3µH 4 5 9 8 R2 SHORT (PC TRACE) R1 OPEN D1 OPEN C4 0.68µF R3 4.7Ω 5% C2 100µF 6.3V GND C3 1µF 10V VOUT +3.3V VOUT Evaluates: MAX1760 VIN +1.1V TO VOUT MAX1760 Evaluation Kit Figure 1. MAX1760 EV Kit Schematic 3 Evaluates: MAX1760 MAX1760 Evaluation Kit 1.0" 1.0" Figure 2. MAX1760 EV Kit Component Placement Guide— Top Silkscreen 1.0" Figure 3. MAX1760 EV Kit Component Placement Guide— Bottom Silkscreen 1.0" Figure 4. MAX1760 EV Kit PC Board Layout—Component Side Figure 5. MAX1760 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.