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19-1457; Rev 1; 7/00
MAX1644 Evaluation Kit
General Description
The MAX1644 evaluation kit (EV kit) provides a 1.5V output voltage from a +3V to +5.5V input source. It delivers up to 2A output current with 92% (max) efficiency. The MAX1644 is a step-down switching regulator with an internal synchronous rectifier to reduce the number of external components. It features a resistorprogrammable fixed off-time as well as current-mode operation for superior load- and line-transient response. The MAX1644 EV kit can also be used to evaluate other output voltages by changing the feedback resistors (R1 and R2) or by using the preset +3.3V or +2.5V settings. o +3V to +5.5V Input Voltage Range o Output Voltage Preset to 1.5V 2.5V or 3.3V Selectable 1.1V to VIN Adjustable o 2A Output Current o 92% Efficiency o 300kHz Switching Frequency o Synchronous Rectification for Improved Efficiency o No External Schottky Diode Required o Less than 1A typical IC Shutdown Current o Surface-Mount Construction o Fully Assembled and Tested
Features
Evaluates: MAX1644
Component List
DESIGNATION QTY DESCRIPTION 10F, 6.3V, X5R ceramic capacitors Taiyo Yuden JMK316BJ106ML or Murata GRM42-6X5R106K6.3 100F, 6.3V, low-ESR capacitor Sanyo 6TPC100M (POSCAP), AVX TPSD107M010R0080 (tantalum), Sprague 594D107X0010C2T (tantalum) 2.2F, 10V, X5R ceramic capacitor Taiyo Yuden LMK212BJ225MG 0.01F, 50V, X7R ceramic capacitor 470pF, 50V, X7R ceramic capacitor 1F, 10V, X7R ceramic capacitor Taiyo Yuden LMK212B105KG or Murata GRM40X7R105K010 Not installed Not installed 2-pin header 6.0H, 2.25A inductor Sumida CDRH6D28-6R0NC 49.9k 1% resistor 18.2k 1% resistor 10 5% resistor 1M 5% resistor 270k 5% resistor Maxim MAX1644EAE Shunt
C1, C8, C9
3
Ordering Information
PART MAX1644EVKIT TEMP. RANGE 0C to +70C IC PACKAGE 16 SSOP
C2
1
Component Suppliers
SUPPLIER AVX Murata Sanyo Sprague Sumida Taiyo Yuden PHONE 803-946-0690 814-237-1431 619-661-6835 603-224-1961 847-956-0666 408-573-4150 FAX 803-626-3123 814-238-0490 619-661-1055 603-224-1430 847-956-0702 408-573-4159
C3 C4 C5 C6 C7 D1 JU1 L1 R1 R2 R3 R4 R5 U1 None
1 1 1 1 0 0 1 1 1 1 1 1 1 1 1
_________________________Quick Start
The MAX1644 EV kit is a fully assembled and tested surface-mount board. Follow the steps below to verify board operation. Do not turn on the power supply until all connections are completed. 1) Connect a +3V to +5.5V supply to the pads marked VIN and GND. 2) Connect a voltmeter and load (if any) to VOUT and GND. 3) Verify that the shunt is on JU1. 4) Turn on the power and verify that the output voltage is +1.5V. 5) Refer to Output Voltage Selection to modify the board for a different output voltage.
1
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
MAX1644 Evaluation Kit Evaluates: MAX1644
________________ Detailed Description
The MAX1644 EV kit provides a 1.5V output voltage from a +3V to +5.5V input voltage. It delivers up to 2A of output current.
Output Voltage Selection
The MAX1644 EV kit is programmed for a 1.5V output voltage. However, the output voltage may also be adjusted by changing the resistor divider formed by R1 and R2 or by using the preset +2.5V or +3.3V settings. For selecting the resistor values, refer to Setting the Output Voltage in the MAX1644 data sheet. To use the preset +2.5V or +3.3V settings, place a short across JU3 and cut the trace between pins 1 and 4 of JU2. See Table 2 for further instructions.
Jumper Selection
The 2-pin header JU1 selects the MAX1644's shutdown mode. Table 1 lists the jumper options.
Table 1. Jumper JU1 Functions
SHUNT LOCATION Open SHDN PIN MAX1644 OUTPUT
Thermal Resistance
The MAX1644's junction-to-ambient thermal resistance is 60C/W, based on the MAX1644 EV kit printed circuit board.
Connected to GND Shutdown mode, through 1M (R4) VOUT = 0 Connected to VIN MAX1644 enabled VOUT = +1.5V
Closed (Default)
Table 2. Output Voltage Configurations
OUTPUT VOLTAGE 1.1 1.5 2.5 3.3 Adjustable JU3 Closed Open Closed Closed Open JU2 Short 1-4 (default trace) Short 1-4 (default trace) Cut default trace across 1-4; short 1-2 Cut default trace across 1-4; leave open Short 1-4 R2 Shorted by JU3 Default value Shorted by JU3 Shorted by JU3 Change
2
_______________________________________________________________________________________
Figure 1. MAX1644 EV Kit Schematic
R3 10 C1 10F 6.3V 2 12 V+ IN L1 6.0H C8 10F 6.3V C9 10F 6.3V VOUT +1.5V
VIN +3V TO +5.5V
GND
U1
LX 14
4 IN LX 16
C3 2.2F JU1 1 SHDN R4 1M 5 SS CC TOFF FBSEL 11 PINS 1 AND 4 SHORTED WITH PC BOARD TRACE 2 4 JU2 3 1 C6 1F 6 7 C4 0.01F R5 270k C5 470pF
MAX1644
C2 6.3V 100F
GND
3 LX 15 PGND 13 PGND 8 FB 10 REF 9 GND PGND C7 OPEN
GND
R2 18.2k 1% R1 49.9k 1%
JU3
Evaluates: MAX1644
_______________________________________________________________________________________
NOTE: HEAVY LINES DENOTE HIGH-CURRENT PATHS.
MAX1644 Evaluation Kit
3
MAX1644 Evaluation Kit Evaluates: MAX1644
1.0"
1.0"
Figure 2. MAX1644 EV Kit Component Placement Guide-- Component Side
Figure 3. MAX1644 EV Kit PC Board Layout--Component Side
1.0"
Figure 4. MAX1644 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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