Page 1
LX1918 EVALUATION BOARD USER GUIDE
SYNCHRONOUS BUCK CONVERTER
LX1918 EVALUATION BOARD
Copyright © 2004
Rev. 1.2, 2005-12-02
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
INTEGRATED PRODUCTS
Microsemi
Integrated Products
Page 1
Page 2
LX1918 EVALUATION BOARD USER GUIDE
TABLE OF CONTENTS
LX1918 EVAL Introduction................................................................................................................................3
Schematic for LX1918 Evaluation Board............................................................................................................... 4
Hook Up................................................................................................................................................................. 5
Connections........................................................................................................................................................... 6
Bill of Materials....................................................................................................................................................... 6
Copyright © 2004
Rev. 1.2, 2005-12-02
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Microsemi
Integrated Products
Page 2
Page 3
LX1918 EVALUATION BOARD USER GUIDE
INTRODUCING TO PRODUCT
The LX1918 Evaluation Board is available from Microsemi for demonstrating the performance of the LX1918
Synchronous Buck Converter.
KEY FEATURES
• 2.7V to 6.0V Input Range
• 1.5A Output Current
• 1Mhz free running or 500KHz to 1.25MHz Switching Frequency
• 0.6V Reference Voltage Adjustment
• PFM or PWM Mode
• EMI Support With Force PWM Mode
• Light Load Support: I
• > 95% Efficiency
• Quiescent Current Typical 400µA
• No External Schottky Diode
• Thermal Shutdown
• Cycle By Cycle Switch Current Limit
• UVLO Protection
• Current Limiting in Hiccup Mode
• 8-Pin MLP package (3mm
APPLICATIONS
< 300mA
OUT
2
)
• Lower Power Embedded Applications
• WLAN Power Systems
• Portable Design with Single Cell LiIon or 3 Cell NiMH / NiCd
• Low Power Portable Storage Application
P
ART SPECIFIC INFORMATION
Part Number
LX1918CLD 1.5A Step-Down Synchronous Converter
TABLE 1 – PART INFORMATION
IC EVALUATION BOARDS
LX1918CLD LX1918-LD EVAL
TABLE 2 – EVALUATION BOARD INFORMATION
Description
Copyright © 2004
Rev. 1.2, 2005-12-02
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Microsemi
Integrated Products
Page 3
Page 4
LX1918 EVALUATION BOARD USER GUIDE
SCHEMATIC FOR LX1918 EVAL
VIN
GND
PVIN
C1
4.7µF
C3
0.1µF
P2
ENOSC
R4
10K
PVIN
U1 LX1918
1
8
FB ES
SHDN
LO EMI
HI EFF
E/S
P1
MODE
R3
10K
PVIN
2
AGND
3
PGND
45
SW
L1 3.3µH
R2 1K
MODE
AVIN
PVIN
1.5K
R1
7
6
R5 40
VOUT
C2
47µF
GND
Figure 1 – Evaluation Board Schematic
Copyright © 2004
Rev. 1.2, 2005-12-02
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Microsemi
Integrated Products
Page 4
Page 5
LX1918 EVALUATION BOARD USER GUIDE
LX1918 EVALUATION HOOK UP
The following is a demonstration scenario to be used
for evaluating the LX1918.
H
OOK UP DIRECTION
1. Place Mode Jumper in HI EFF (high
efficiency) position.
VIN
+
Power
IN
_
+
External
SYNC
_
500Khz-1.25Mhz Min
1.6V signal
Note: to use external sync
mode select must be in
LO EMI mode
LO EMI
R3
MODE
31
GND
HI EFF
LX1918 STEP-DOWN SYNCHRONOUS CONVERTER
Figure 2 – Evaluation Board Hook Up
C1
VIN
U
1
R5
C3
R2 R1
ENOSC SHDN
R4
E/S
INTEGRATED PRODUCTS
EVALUATION PCB
2. Place E/S Jumper in ENOSC position.
3. Apply 3.6V / 2A input between VIN and
GND.
4. Connect to Load capable of handling the
prescribed output (Board is set to 1.5V
output by default).
L1
VOUT
C2
Vout
GND
31
Load
+
-
.
Copyright © 2004
Rev. 1.2, 2005-12-02
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Microsemi
Integrated Products
Page 5
Page 6
LX1918 EVALUATION BOARD USER GUIDE
C
ONNECTIONS
The LX1918 Evaluation board has 4 test lead
attachment points for applying power and control
signals and for monitoring voltages. There are also 2
– 3 pin connections to select external synchronization
Function Board Label Connection
Input Power VIN Power Supply (2.70V ±6.0V)
Power Ground GND Common Power Supply Ground
External Sync / Shutdown E/S
Connect to GND to disable LX1918. A PWM > 500KHz logic
PWM signal can also be applied
Output Voltage VOUT Test Point – Hook up load and monitor VOUT
Mode Select Mode High Efficiency = Pin 2 and 3. Low EMI = Pin 1 and 2.
1 – To use external synchroization feature the Mode Select must be in Lo EMI position.
ILL OF MATERIALS
B
Line
Item
1 1.5A Synchronous Buck Converter
2 Inductor 1.8A Shielded SMD 3.3µH
3 Header 3 Pin .100 P1, P2 2
4 Test Point – 0.045 diameter, Wire Loop
5 PCB SGE # 3534 X1
Line
Item
1 Capacitor, 4.7µF, X5R, 10V, 20%
2 Capacitor, 47µF, X5R, 6.3V, 20%
3 Capacitor, 0.1µF, X5R, 16V, 20%
Line
Item
1 Resistor, 1.5K, 1/16W, 5%
2 Resistor, 1K, 1/16W, 5%
3 Resistor, 10K, 1/16W, 5%
4 Resistor, 40.2, 1/10W, 1%
Part Description Manufacturer & Part # Case
Part Description Part Description Case
Part Description Part Description Case
MISCELLANEOUS COMPONENTS
MICROSEMI LX1918CLD
COILCRAFT MOS6020-332MX
KEYSTONE 5004_Term
CAPACITORS
TAIYO YUDEN CELDK212BJ475MG
TAIYO YUDEN JMK325BJ476MM
TAIYO YUDEN CEEMK107BJ104MA
RESISTORS
PANASONIC ERJ-3GSYJ152V
PANASONIC ERJ-3GSYJ102V
PANASONIC ERJ-3GSYJ103V
PANASONIC ERJ-3EKF40R2
and operating mode. The E/S selector also has
shutdown capability
1
.
Reference
Designators
LD U1 1
L1 1
4
Reference
Designators
0805 C1 1
1210 C2 1
0603 C3 1
Reference
Designators
0603 R1 1
0603 R2 1
0603 R3, R4 2
0603 R5 1
Qty
Qty
Qty
Copyright © 2004
Rev. 1.2, 2005-12-02
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Microsemi
Integrated Products
Page 6
Loading...