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19-2651; Rev 0; 10/02
MAX1973/MAX1974 Evaluation Kit
General Description
The MAX1973/MAX1974 evaluation kit (EV kit) is a fully assembled and tested circuit board with separate circuits to evaluate the MAX1973 and MAX1974. Both circuits have an input voltage range of 2.6V to 5.5V. The output of the MAX1973 circuit (OUT1) is a selectable preset of 2.5V or 1.8V, or can be adjusted from 1.25V to VIN by adding external feedback resistors. The output of the MAX1974 circuit (OUT2) is a selectable preset of 1.5V or 1V, or can be adjusted from 0.75V to VIN by adding external feedback resistors. Each output can deliver 1A. The MAX1973 circuit also features jumper-selected voltage margining, which allows the output voltage to be increased or decreased by 4%, while the MAX1974 circuit features a power-OK (POK) output that indicates when the regulator output voltage is in regulation. o Tiny 0.19in2 Circuit Footprint o Ultra-Low 1.8mm Circuit Height o 4.7F Ceramic Input and Output Capacitors o 2.6V to 5.5V Input Voltage Range o Up to 1A Output Current o 1% Accurate Output Voltage o Built-In 4% Logic-Controlled Voltage Margining (MAX1973) o Preset 1V, 1.5V, 1.8V, and 2.5V Outputs or 0.75V to VIN Adjustable Output o Fixed-Frequency Current-Mode PWM Operation o 1.4MHz Switching Frequency--Operation Outside DSL Band o 100% Duty Cycle Dropout Capability o Power-OK Output (MAX1974)
Features
Evaluate: MAX1973/MAX1974
Component Suppliers
SUPPLIER Murata Sumida Taiyo Yuden PHONE 770-436-1300 847-956-0666 408-573-4150 WEBSITE www.murata.com www.sumida.com www.t-yuden.com
o Fully Assembled and Tested
Ordering Information
PART MAX1973EVKIT TEMP RANGE -40C to +85C IC PACKAGE 10 MAX
Note: Please indicate that you are using the MAX1973/MAX1974 when contacting these component suppliers.
Component List
DESIGNATION C1, C3, C5, C7 QTY 4 DESCRIPTION 4.7F 10%, 6.3V X5R capacitors (0805) Taiyo Yuden JMK212BJ475KG 560pF 5%, 50V (0603) capacitor Murata GRM39COG561J50 0.1F 10%, 16V X7R capacitors (0603) Taiyo Yuden EMK107BJ104KA 330pF 5%, 50V (0603) capacitor Murata GRM39COG331J50 3-pin headers Shunts DESIGNATION L1, L2 R1 R2, R4 R3, R5 R6 R7 U1 U2 None None QTY 2 1 0 0 1 1 1 1 1 1 DESCRIPTION 3.3H, 1.1A inductors Sumida CDRH3D16-3R3 43k 5% resistor (0603) Not installed, PC board short (0603) Not installed (0603) 43k 5% resistor (0603) 100k 5% resistor (0603) MAX1973EUB, 10-pin MAX MAX1974EUB, 10-pin MAX MAX1973 EV kit PC board MAX1973 EV kit data sheet
C2
1
C4, C8
2
C6 JU1-JU5 --
1 5 5
________________________________________________________________ Maxim Integrated Products
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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.
MAX1973/MAX1974 Evaluation Kit Evaluate: MAX1973/MAX1974
Quick Start
MAX1973 Circuit
Follow the steps below to verify operation of the MAX1973 circuit. Do not turn on the power supply until all connections are completed: 1) Verify that the shunts on JU2 and JU3 are across pins 1 and 2. 2) Set JU1 for the desired output voltage. 3) Connect a voltmeter and load from OUT1 to GND1. 4) Preset the power supply to between 2.6V and 5.5V, and turn supply off. 5) Connect the power supply to IN1 and GND1. 6) Turn on the power supply and verify the output voltage. 4) Calculate the value for R2 using the equation: V R2 = R 3 x OUT - 1 1.25 5) Install resistors R2 and R3. 6) Refer to the MAX1973/MAX1974 data sheet to determine the optimum value for compensation resistor R1. Voltage Margining and Shutdown (MAX1973) Voltage margining and shutdown are selected using jumpers JU2 and JU3 (see Table 2).
Table 2. JU2 and JU3 Functions
JU2 1-2 2-3 1-2 2-3 JU3 1-2 1-2 2-3 2-3 CTL1 PIN IN1 GND1 IN1 GND1 CTL2 PIN IN1 IN1 GND1 GND1 OUT1 Nominal +4% -4% Shutdown
MAX1974 Circuit
Follow the steps below to verify operation of the MAX1974 circuit. Do not turn on the power supply until all connections are completed: 1) Verify that the shunt on JU5 is across pins 1 and 2. 2) Set JU4 for the desired output voltage. 3) Connect a voltmeter and load from OUT2 to GND2. 4) Preset the power supply to between 2.6V and 5.5V, and turn supply off. 5) Connect the power supply to IN2 and GND2. 6) Turn on the power supply and verify the output voltage.
MAX1974 Circuit
Selecting Preset Output Voltages (MAX1974) The MAX1974 circuit is configured for preset output voltages, selected with jumper JU4 as shown in Table 3.
Table 3. JU4 Functions
SHUNT LOCATION 1-2 2-3 FBSEL PIN IN2 GND2 OUT2 (V) 1.5 1
Detailed Description
MAX1973 Circuit
Selecting Preset Output Voltages (MAX1973) The MAX1973 circuit is configured for preset output voltages, selected with jumper JU1 as shown in Table 1.
Table 1. JU1 Functions
SHUNT LOCATION 1-2 2-3 FBSEL PIN IN1 GND1 OUT1 (V) 2.5 1.8
Adjustable Output Voltage (MAX1974) The output voltage of the MAX1974 circuit can also be adjusted from 0.75V to VIN. To set the output voltage of the MAX1974 circuit, use the following procedure: 1) Cut the trace shorting the pads for R4. 2) Remove the jumper from JU4. 3) Select a resistor value for R5 from 1k to 22k. 4) Calculate the value for R4 using the equation:
Adjustable Output Voltage (MAX1973) The output voltage of the MAX1973 circuit can also be adjusted from 1.25V to VIN. To set the output voltage of the MAX1973 circuit, use the following procedure: 1) Cut the trace shorting the pads for R2. 2) Remove the jumper from JU1. 3) Select a resistor value for R3 from 1k to 22k.
V R4 = R5 x OUT - 1 0.75 5) Install resistors R4 and R5. 6) Refer to the MAX1973/MAX1974 data sheet to determine the optimum value for compensation resistor R6.
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MAX1973/MAX1974 Evaluation Kit
Table 4. JU5 Functions
SHUNT LOCATION 1-2 2-3 EN PIN IN2 GND2 OUT2 Active Shutdown
Power-OK (POK-MAX1974) POK is an open-drain output that pulls low when the output voltage is below 90% of its nominal regulation voltage. A 100k pullup resistor is connected from POK to OUT2. If a pullup resistor is not desired, cut the trace shorting jumper JU6.
Evaluate: MAX1973/MAX1974
Shutdown (MAX1974) JU5 is used to select shutdown mode on the MAX1974 circuit. Place jumper JU5 between pins 1 and 2 for normal operation, or place jumper JU5 between pins 2 and 3 to select shutdown mode. See Table 4.
L1 3.3H LX 8 3 7 4 C4 0.1F R3 OPEN R2 PC BOARD SHORT C3 4.7F
IN1 1 C1 4.7F 1 2 3 1 GND1 2 3 JU2 JU3 2 3 JU1
9 1 10 6
U1
IN FBSEL CTL1 CTL2 COMP GND 2 5 R1 43k C2 560pF
OUT1
MAX1973
FB PGND SS
Figure 1. MAX1973/MAX1974 EV Kit Schematic (MAX1973 Circuit)
IN2 1 C5 4.7F 1 2 3 JU5 2 3 JU4
9 1 10 6
U2
IN FBSEL ON POK COMP GND 2 5 R6 43k C6 330pF R7 100k LX
L2 3.3H 8 3 7 4 C8 0.1F R5 OPEN R4 PC BOARD SHORT
OUT2
MAX1974
FB PGND SS
C7 4.7F
GND2
JU6
POK
Figure 2. MAX1973/MAX1974 EV Kit Schematic (MAX1974 Circuit) _______________________________________________________________________________________ 3
MAX1973/MAX1974 Evaluation Kit Evaluate: MAX1973/MAX1974
Figure 3. MAX1973/MAX1974 EV Kit Component Placement Guide--Component Side
Figure 4. MAX1973/MAX1974 EV Kit Component Placement Guide--Solder Side
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MAX1973/MAX1974 Evaluation Kit Evaluate: MAX1973/MAX1974
Figure 5. MAX1973/MAX1974 EV Kit PC Board Layout-- Component Side
Figure 6. MAX1973/MAX1974 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 _____________________ 5 (c) 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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