MAXIM MAX1973EVKIT

19-2651; Rev 0; 10/02
MAX1973/MAX1974 Evaluation Kit
Features
♦ Tiny 0.19in2 Circuit Footprint
♦ Ultra-Low 1.8mm Circuit Height
♦ 4.7µF Ceramic Input and Output Capacitors
♦ 2.6V to 5.5V Input Voltage Range
♦ Up to 1A Output Current
♦ 1% Accurate Output Voltage
♦ Built-In ±4% Logic-Controlled Voltage Margining
(MAX1973)
♦ Preset 1V, 1.5V, 1.8V, and 2.5V Outputs or
0.75V to VIN Adjustable Output
♦ Fixed-Frequency Current-Mode PWM Operation
♦ 1.4MHz Switching Frequency—Operation Outside
DSL Band
♦ 100% Duty Cycle Dropout Capability
♦ Power-OK Output (MAX1974)
Component Suppliers
SUPPLIER
PHONE
♦ Fully Assembled and Tested
WEBSITE
Murata
770-436-1300
Sumida
847-956-0666
www.murata.com
www.sumida.com
Taiyo Yuden
408-573-4150
www.t-yuden.com
Note: Please indicate that you are using the MAX1973/MAX1974
when contacting these component suppliers.
Ordering Information
PART
MAX1973EVKIT
TEMP RANGE
IC PACKAGE
-40°C to +85°C
10 µMAX
Component List
DESIGNATION
QTY
DESCRIPTION
DESIGNATION
QTY
DESCRIPTION
L1, L2
2
3.3µH, 1.1A inductors
Sumida CDRH3D16-3R3
R1
1
43kΩ ±5% resistor (0603)
R2, R4
0
Not installed, PC board short (0603)
C1, C3, C5, C7
4
4.7µF ±10%, 6.3V X5R capacitors
(0805)
Taiyo Yuden JMK212BJ475KG
C2
1
560pF ±5%, 50V (0603) capacitor
Murata GRM39COG561J50
R3, R5
0
Not installed (0603)
2
0.1µF ±10%, 16V X7R capacitors
(0603)
Taiyo Yuden EMK107BJ104KA
R6
1
43kΩ ±5% resistor (0603)
R7
1
100kΩ ±5% resistor (0603)
U1
1
MAX1973EUB, 10-pin µMAX
U2
1
MAX1974EUB, 10-pin µMAX
C4, C8
C6
1
330pF ±5%, 50V (0603) capacitor
Murata GRM39COG331J50
JU1–JU5
5
3-pin headers
None
1
MAX1973 EV kit PC board
—
5
Shunts
None
1
MAX1973 EV kit data sheet
________________________________________________________________ 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.
1
Evaluate: MAX1973/MAX1974
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.
Evaluate: MAX1973/MAX1974
MAX1973/MAX1974 Evaluation Kit
Quick Start
4) Calculate the value for R2 using the equation:
V

R2 = R 3 ×  OUT − 1
 1.25

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.
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.
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
JU3
CTL1 PIN
CTL2 PIN
OUT1
1-2
1-2
IN1
IN1
Nominal
2-3
1-2
GND1
IN1
+4%
1-2
2-3
IN1
GND1
-4%
2-3
2-3
GND1
GND1
Shutdown
2) Set JU4 for the desired output voltage.
MAX1974 Circuit
3) Connect a voltmeter and load from OUT2 to GND2.
5) Connect the power supply to IN2 and GND2.
Selecting Preset Output Voltages (MAX1974)
The MAX1974 circuit is configured for preset output voltages, selected with jumper JU4 as shown in Table 3.
6) Turn on the power supply and verify the output voltage.
Table 3. JU4 Functions
4) Preset the power supply to between 2.6V and 5.5V,
and turn supply off.
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
FBSEL PIN
OUT1 (V)
1-2
IN1
2.5
2-3
GND1
1.8
SHUNT LOCATION
FBSEL PIN
OUT2 (V)
1-2
IN2
1.5
2-3
GND2
1
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 1kΩ to 22kΩ.
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 1kΩ to 22kΩ.
2
V

R4 = R5 ×  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.
_______________________________________________________________________________________
MAX1973/MAX1974 Evaluation Kit
SHUNT LOCATION
EN PIN
OUT2
1-2
IN2
Active
2-3
GND2
Shutdown
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.
IN1
9
1
JU1
1
2
C1
4.7µF
3
10
6
1
IN
LX
PGND
CTL2
SS
JU3
OUT1
8
3
R2
PC BOARD
SHORT
7
4
COMP GND
2
5
C4
0.1µF
R3
OPEN
C3
4.7µF
R1
43kΩ
2
3
FB
CTL1
1
GND1
MAX1973
FBSEL
2
3
L1
3.3µH
U1
JU2
C2
560pF
Figure 1. MAX1973/MAX1974 EV Kit Schematic (MAX1973 Circuit)
IN2
9
1
2
C5
4.7µF
3
1
10
6
1
2
3
JU4
JU5
GND2
L2
3.3µH
U2
IN
LX
MAX1974
FBSEL
ON
FB
PGND
POK
SS
OUT2
8
3
R4
PC BOARD
SHORT
7
4
COMP GND
2
5
R6
43kΩ
C8
0.1µF
R5
OPEN
C7
4.7µF
C6
330pF
R7
100kΩ
JU6
POK
Figure 2. MAX1973/MAX1974 EV Kit Schematic (MAX1974 Circuit)
_______________________________________________________________________________________
3
Evaluate: MAX1973/MAX1974
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 100kΩ pullup resistor is connected from
POK to OUT2. If a pullup resistor is not desired, cut the
trace shorting jumper JU6.
Table 4. JU5 Functions
Evaluate: MAX1973/MAX1974
MAX1973/MAX1974 Evaluation Kit
Figure 3. MAX1973/MAX1974 EV Kit Component Placement
Guide—Component Side
4
Figure 4. MAX1973/MAX1974 EV Kit Component Placement
Guide—Solder Side
_______________________________________________________________________________________
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
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implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
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is a registered trademark of Maxim Integrated Products.