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 V
IN
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 V
IN
by adding external feed-
back 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 0.19in
2
Circuit Footprint
o
Ultra-Low 1.8mm Circuit Height
o
4.7µF 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 V
IN
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
-40°C to +85°C
IC PACKAGE
10 µMAX
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
4.7µF
±10%,
6.3V X5R capacitors
(0805)
Taiyo Yuden JMK212BJ475KG
560pF
±5%,
50V (0603) capacitor
Murata GRM39COG561J50
0.1µF
±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
3.3µH, 1.1A inductors
Sumida CDRH3D16-3R3
43kΩ
±5%
resistor (0603)
Not installed, PC board short (0603)
Not installed (0603)
43kΩ
±5%
resistor (0603)
100kΩ
±5%
resistor (0603)
MAX1973EUB, 10-pin µMAX
MAX1974EUB, 10-pin µMAX
MAX1973 EV kit PC board
MAX1973 EV kit data sheet
C2
1
C4, C8
2
C6
JU1–JU5
—
1
5
5
________________________________________________________________
Maxim Integrated Products
1
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
×
OUT
−
1
1.25
5) Install resistors R2 and R3.
6) Refer to the MAX1973/MAX1974 data sheet to deter-
mine 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 volt-
ages, 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 volt-
ages, 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 V
IN
. 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 V
IN
. 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.
V
R4
=
R5
×
OUT
−
1
0.75
5) Install resistors R4 and R5.
6) Refer to the MAX1973/MAX1974 data sheet to deter-
mine the optimum value for compensation resistor
R6.
2
_______________________________________________________________________________________
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 100kΩ 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 nor-
mal operation, or place jumper JU5 between pins 2 and 3
to select shutdown mode. See Table 4.
L1
3.3µH
LX
8
3
7
4
C4
0.1µF
R3
OPEN
R2
PC BOARD
SHORT
C3
4.7µF
IN1
1
C1
4.7µF
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
43kΩ
C2
560pF
OUT1
MAX1973
FB
PGND
SS
Figure 1. MAX1973/MAX1974 EV Kit Schematic (MAX1973 Circuit)
IN2
1
C5
4.7µF
1
2
3
JU5
2
3
JU4
9
1
10
6
U2
IN
FBSEL
ON
POK
COMP GND
2
5
R6
43kΩ
C6
330pF
R7
100kΩ
LX
L2
3.3µH
8
3
7
4
C8
0.1µF
R5
OPEN
R4
PC BOARD
SHORT
OUT2
MAX1974
FB
PGND
SS
C7
4.7µF
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
4
_______________________________________________________________________________________
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
© 2002 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
