19-2361; Rev 0; 03/02
MAX1921 Evaluation Kit
General Description
The MAX1921 evaluation kit (EV kit) provides a fixed 1.8V
output voltage from a 2V to 5.5V input source and deliv-
ers up to 400mA output current. The MAX1921 is a step-
down switching regulator with an internal power switch
and synchronous rectifier in a tiny SOT23 package.
The MAX1921 EV kit is a fully assembled and tested
surface-mount circuit board. The MAX1921 EV kit can
also be used to evaluate other fixed-output voltage ver-
sions of the MAX1921 or the MAX1920, which is a step-
down switching regulator with an adjustable output volt-
age. Additional pads on the board are provided for
external feedback resistors to set different output volt-
ages, 1.25V to VIN.
o
2V to 5.5V Input Voltage Range
o
Output Voltage
1.8V Fixed Output Voltage (MAX1921EUT18-T)
Adjustable Output Voltage (MAX1920EUT-T)
Other Fixed-Output Voltages
(MAX1921EUT_ _-T)
o
Output Current
Guaranteed 400mA at
≥2.5V
Input Voltage
o
IC Shutdown Current
0.1µA (typ)
o
Surface-Mount Components
o
Fully Assembled and Tested
Features
Evaluates: MAX1920/MAX1921
Component List
DESIGNATION
QTY
DESCRIPTION
2.2µF ±20%, 10V X5R
ceramic capacitor (0805)
Taiyo Yuden LMK212BJ225MG or
TDK C2012X5R1A225M
4.7µF ±20%, 6.3V X5R
ceramic capacitor (0805)
Taiyo Yuden JMK212BJ475MG or
TDK C2012X5R0J475K
5.6nF ±20%, 50V X7R
ceramic capacitor (0603)
Murata GRM39X7R562M050AD or
equivalent
3-pin header
4.7µH ±20% 1A inductor
Toko A914BYW-4R7M or
Sumida CDRH3D16-4R7
4.75kΩ ±1% resistor (0603)
Not installed, resistor (0603)
MAX1921EUT18-T
(6-pin SOT23), top mark ABCM
Shunt
MAX1921 PC board
MAX1921 EV kit data sheet
MAX1920/MAX1921 data sheet
PART
MAX1921EVKIT
Ordering Information
TEMP RANGE
0
o
C to +70
o
C
IC PACKAGE
6 SOT23-6
C1
1
Note:
To evaluate other versions of the MAX1921 or the
MAX1920, request a free sample with the MAX1921EVKIT.
See Table 2.
C2
1
Quick Start
The MAX1921 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) Verify that there is a shunt across pins 1 and 2 of
JU1 (SHDN).
2) Connect a voltmeter and load (if any) to the VOUT
pad. Connect the ground to the GND closest to
VOUT.
3) Connect a 2V to 5.5V power supply to the VIN pad.
Connect power supply ground to the GND pad
closest to VIN.
4) Turn on the power supply and verify that the output
voltage is 1.8V.
To evaluate other voltages, see the
Evaluating Other
Output Voltages
section.
C3
1
JU1
L1
R1
R2
U1
None
None
None
None
1
1
1
0
1
1
1
1
1
________________________________________________________________
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.
MAX1921 Evaluation Kit
Evaluates: MAX1920/MAX1921
Component Suppliers
SUPPLIER
Sumida
Taiyo Yuden
TDK
Toko
PHONE
847-545-6700
800-348-2496
847-803-6100
847-297-0070
FAX
847-545-6720
847-925-0899
847-390-4405
847-699-1194
WEBSITE
www.sumida.com
www.t-yuden.com
www.tdk.com
www.tokoam.com
Note:
Please indicate that you are using the MAX1920/MAX1921 when contacting these component suppliers.
Detailed Description
Shutdown Mode
The MAX1921 EV kit features a shutdown mode that
reduces the MAX1921 quiescent current to 0.1µA, pre-
serving battery life. The setting of jumper JU1 selects
the circuit operating modes. Table 1 shows the func-
tions of JU1.
Evaluating Other Output Voltages
The MAX1921 EV kit can be used to evaluate the
MAX1921EUT15-T/25-T/30-T/33-T and the MAX1920EUT-T.
Replace MAX1921EUT18-T with a MAX1921EUT15-T/25-
T/30-T/33-T or MAX1920EUT-T. Table 2 lists the corre-
sponding output voltages. To evaluate different output
voltages, select L1, C2, C3, R1, and R2 for optimum per-
formance according to the
Design Procedure
section of
the MAX1920/MAX1921 data sheet.
Table 1. JU1 Functions
SHUNT
LOCATION
1 and 2
2 and 3
SHDN
PIN
Connected to
VIN
Connected to
GND
Connected to
SHDN
pad
MAX1921 OUTPUT
MAX1921 enabled,
VOUT = 1.8V
MAX1921 disabled,
VOUT = 0V
External signal
enables or disables
the MAX1921 output
Table 2. MAX1921 EV Kit Corresponding
Output Voltage
PART NUMBER
MAX1920EUT-T
MAX1921EUT15-T
MAX1921EUT18-T
MAX1921EUT25-T
MAX1921EUT30-T
MAX1921EUT33-T
MAX1921 EV KIT OUTPUT
VOLTAGE (V)
Adjustable
1.5
1.8
2.5
3.0
3.3
Open
2
_______________________________________________________________________________________
MAX1921 Evaluation Kit
Evaluates: MAX1920/MAX1921
1.0"
Figure 4. MAX1921 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
© 2002 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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