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19-1660; Rev 0; 8/00
MAX1760 Evaluation Kit
General Description
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. o +0.7V to +5.5V Input Voltage o +3.3V Output Voltage o Internal Synchronous Rectifier Provides up to 96% Efficiency o Output is Adjustable with External Resistors o Up to 800mA Output o On-Chip N-Channel Switch o 1A Shutdown Current o 1MHz Switching Frequency o Fixed-Frequency PWM Operation o Surface-Mount Components o Fully Assembled and Tested
Features
Evaluates: MAX1760
Component List
DESIGNATION QTY C1 C2 C3 C4 C5 C6 D1 L1 R3 R1, R2, R4, R5 U1 JU1, JU2 None None None None 1 1 1 1 1 0 1 1 1 0 1 2 2 1 1 1 DESCRIPTION 33F, 16V, low-ESR electrolytic cap Sanyo 16TPC33M 100F, 6.3V, low-ESR electrolytic cap Sanyo 6TPC100M 1F, 10V, X5R ceramic cap (0805) Taiyo Yuden LMK212BJ105MG 0.68F, 10V, X5R ceramic cap (0805) Taiyo Yuden LMK212BJ684KG 0.22F, 25V, X7R ceramic cap (1206) Taiyo Yuden TMK316BJ224KF Not installed (0805) Not installed, Nihon EP10QY03 3.3H, 1.4A inductor Coilcraft DO1606T-332 4.7 5% resistor (0805) Not installed (0805) Maxim MAX1760EUB (10-pin MAX) 3-pin headers Shunts (JU1, JU2) MAX1760 PC board MAX1760 data sheet MAX1760 EV kit data sheet SUPPLIER Coilcraft Nihon USA Sanyo USA Taiyo Yuden PART MAX1760EVKIT
Ordering Information
TEMP. RANGE 0C to +70C IC PACKAGE 10 MAX
Component Suppliers
PHONE 847-639-6400 661-867-2555 619-661-6835 408-573-4150 FAX 847-639-1469 661-867-2698 619-661-1055 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
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MAX1760 Evaluation Kit Evaluates: MAX1760
Table 1. Jumper JU1 Functions
SHUNT LOCATION 1-2 2-3 ON PIN Connected to VOUT Connected to GND MAX1760 OUTPUT Shutdown mode, VOUT = VIN - VDIODE MAX1760 enabled, VOUT = +3.3V
Table 2. Jumper JU2 Functions
SHUNT LOCATION 1-2 CLK/SEL PIN OPERATING MODE Forced PWM mode: PWM operation at all loads Normal mode: PFM at light load and PWM at medium to heavy load PWM mode synchronized to external 500kHz to 1200kHz range clock
Connected to VOUT
2-3
Connected to GND
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.
None
Clock connected to CLK/SEL pad
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.
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 1A (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.
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 1M 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.
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Figure 1. MAX1760 EV Kit Schematic
L1 3.3H
D1 OPEN
VIN +1.1V TO VOUT
VOUT +3.3V
C1 33F 16V C2 100F 6.3V C3 1F 10V
3 2
VOUT
ON
JU1
10 ON LX 8
1
U1
VOUT
MAX1760
1 2
CLK/SEL
JU2
6 CLK/SEL POUT 9
3 2 REF OUT 5
R3 4.7 5% C4 0.68F R1 OPEN
C5 0.22F 25V
ISET GND PGND 7 3 FB 4
R4 SHORT 1 R5 OPEN C6 OPEN
Evaluates: MAX1760
_______________________________________________________________________________________
R2 SHORT (PC TRACE) GND
GND
MAX1760 Evaluation Kit
3
MAX1760 Evaluation Kit Evaluates: MAX1760
1.0"
1.0"
Figure 2. MAX1760 EV Kit Component Placement Guide-- Top Silkscreen
Figure 3. MAX1760 EV Kit Component Placement Guide-- Bottom Silkscreen
1.0"
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 (c) 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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