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19-1817; Rev 0; 10/00
MAX1744 Evaluation Kit
General Description
The MAX1744 evaluation kit (EV kit) provides a selectable 3.3V or 5V output voltage from input as high as 36V. The MAX1744 operates up to 100% duty cycle, extending the usable input voltage range. The 100% duty cycle and a low 100mV current-sense level permit very low dropout voltages. The circuit is configured to deliver up to 2A of output current with greater than 90% conversion efficiency. The output current can be increased by changing the external components. This EV kit is a fully assembled and tested circuit board. It can also be used to evaluate the MAX1745, which has an adjustable output voltage, by selecting feedback resistors R2 and R3. o High Input Voltage (up to 36V) o Selectable 3.3V or 5V Output Voltage (MAX1744) o 1.25V to 18V Adjustable Output Voltage (MAX1745) o Low Dropout Voltage o 100% Maximum Duty Cycle o 2A Output Current o Up to 330kHz Switching Frequency o 4A IC Shutdown Current o 10-Pin MAX Package o Fully Assembled and Tested
Features
Evaluates: MAX1744/MAX1745
Ordering Information
PART MAX1744EVKIT TEMP. RANGE 0C to +70C IC PACKAGE 10 MAX
Note: To evaluate the MAX1745, request a MAX1745EUB free sample with the MAX1744EVKIT.
Component List
DESIGNATION C1, C2 QTY 2 DESCRIPTION 120F, 63V electrolytic capacitors Sanyo 63MV120GX 220F, 10V tantalum capacitor AVX TPSE227M010R0100 or Sprague 593D227X0010E 2W 4.7F, 16V tantalum capacitors Sprague 595D475X0016A 2B 0.1F ceramic capacitor (1206) 0.47F ceramic capacitor (1206) 2A, 60V Schottky diode Nihon EC21QS06 or Central Semiconductor CMSH2-60 22H inductor Sumida CDRH104R-220MC (shielded), Sumida CDRH124220MC (shielded), Coilcraft DO3316P-223 (unshielded), or Coiltronics UP2B-220 (unshielded) DESIGNATION P1 R1 R2, R3 U1 JU1, JU2 None None None None QTY 1 1 0 1 2 2 1 1 1 DESCRIPTION 60V P-channel MOSFET Fairchild NDS9407 0.033 1% resistor (2010) Dale WSL-2010-R033F or IRC LR2010-R033F Not installed MAX1744EUB (10-pin MAX) 3-pin headers Shunts MAX1744/MAX1745 PC board MAX1744/MAX1745 data sheet MAX1744 EV kit data sheet
C3 C4, C5 C6 C7 D1
1 2 1 1 1
L1
1
________________________________________________________________ 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.
MAX1744 Evaluation Kit Evaluates: MAX1744/MAX1745
Quick Start
The MAX1744 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) Verify that the shunt on JU1 is across pins 1 and 2. 2) Verify that the shunt on JU2 is across pins 1 and 2 for a 5V output. 3) Connect a voltmeter and load, if any, to the VOUT pad. 4) Connect a 5.5V to 36V supply voltage to the VIN pad. Connect ground to the GND pad. 5) Turn on the power supply. Verify that the output voltage is 5V. 6) Remove the shunt from JU2 pins 1 and 2, and place it across pins 2 and 3 for a 3.3V output voltage.
Detailed Description
Evaluating Other Output Voltages
To generate output voltages other than 3.3V or 5V, replace the MAX1744 with the MAX1745 (adjustable output), and select the external voltage-divider resistors, R2 and R3. The MAX1745 allows the output voltage to be set from 1.25V to 18V. The only other modification required is to remove the shunt from JU2. For output voltages greater than 5V, replace output capacitor C3 with a higher voltage rating. Refer to the Setting the Output Voltage section in the MAX1744/ MAX1745 data sheet for instructions on calculating R2 and R3 values.
Table 1. Jumper JU1 Functions (Shutdown Mode)
SHUNT LOCATION 1 and 2 2 and 3 SHDN PIN Connected to VL Connected to GND OUTPUT VOLTAGE MAX1744 enabled Shutdown mode, VOUT = 0
Component Suppliers
SUPPLIER AVX Central Semiconductor Coilcraft Coiltronics Dale-Vishay Fairchild IRC OUTPUT VOLTAGE Nihon Sanyo Sprague Sumida PHONE 803-946-0690 516-435-1110 708-639-6400 561-241-7876 402-564-3131 408-721-2181 361-992-7900 847-843-7500 619-661-6835 603-224-1961 708-956-0666 FAX 803-626-3123 516-435-1824 708-639-1469 561-241-9339 402-563-6418 408-721-1635 361-992-3377 847-843-2798 619-661-1055 603-224-1430 708-956-0702
Table 2. Jumper JU2 Functions (Output Voltage Selection)
SHUNT LOCATION 1 and 2 2 and 3 3/5 PIN Connected to VL Connected to GND
VOUT = 5V VOUT = 3.3V
Note: Please indicate that you are using the MAX1744/MAX1745 when contacting these component suppliers.
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MAX1744 Evaluation Kit Evaluates: MAX1744/MAX1745
VIN 36V MAX C1 120F 63V 8 VH EXT 9 41 5 6 2 3 P1 8 7 L1 22H R1 0.033 C3 220F 10V VOUT 5V, 2A C2 120F 63V
C4 4.7F 16V 10 C7 0.47F JU1 2 7 SHDN V+
VIN
SHDN
1 3
U1 MAX1744 MAX1745
GND 1
D1
GND
VL 5V C5 4.7F 16V REF 1.25V
2
VL
CS OUT
6 5 VL
3 REF C6 0.1F
(FB) 3/5
4
1 JU2 3 R2 OPEN R3 OPEN
2
( ) ARE FOR MAX1745 ONLY.
Figure 1. MAX1744 EV Kit Schematic
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MAX1744 Evaluation Kit Evaluates: MAX1744/MAX1745
1.0"
1.0"
Figure 2. MAX1744 EV Kit Component Placement Guide--Top Silkscreen
Figure 3. MAX1744 EV Kit Component Placement Guide-- Bottom Silkscreen
1.0"
1.0"
Figure 4. MAX1744 EV Kit PC Board Layout--Component Side
Figure 5. MAX1744 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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