LX1918
TM
廬
1.8A Step-Down Synchronous Converter
P
RODUCTION
D
ATA
S
HEET
DESCRIPTION
KEY FEATURES
Input range voltage 2.7 to 5.5V
Maximum output current, 1.8A
Internal or External
Synchronization
Output Voltage from V
IN
to 0.6V
PFM or PWM mode under light
load
EMI support with force PWM
mode
Efficiency up to 95%
No external Schottky diode
Thermal shutdown
Cycle by cycle switch current
limit
UVLO
Short circuit protection
8 pin MLP
APPLICATIONS
The Microsemi LX1918 is a step
down buck regulator with a
synchronous rectifier. All MOSFET
switches and compensation com-
ponents are built in. The synchronous
rectification eliminates the need of an
external
Schottky
diode
and
maximizes efficiency (>95%) for a
high step-down ratio and a low output
voltage. The input supply voltage
range is from 2.7V to 5.5V with a
maximum output current of 1.8A.
The LX1918 is a current mode
PWM with optional PFM under light
loads. The LX1918 can switch with a
1MHz free running internal oscillator
or be synchronized with an external
oscillator ranging from 500KHz to
1.25MHz; the high frequency allows
for small size and low cost external
components. The LX1918 output
voltage is programmable with two
resistors and can be tightly regulated
down to 0.6V.
The LX1918 MODE feature can
either maximize efficiency or reduce
EMI depending on the needs of the
application. High efficiency (MODE =
GND) is obtained by allowing the
LX1918 to enter a PFM mode with
discontinuous inductor current. Low
EMI (MODE=VCC) is obtained by
only operating in PWM mode even at
no load.
The LX1918 features include soft
start, cycle-by-cycle switch current
limit, hiccup short circuit current
limiting and thermal shut down.
The LX1918 comes in small 8 pin
MLP package (fully RoHS compliant).
WWW .
Microsemi
.C
OM
IMPORTANT:
For the most current data, consult
MICROSEMI鈥檚
website:
http://www.microsemi.com
Lower power embedded
applications
WLAN power system
Portable design with single cell
Lion or 3 cells NiMH/NiCd
Low power portable storage
application
PRODUCT HIGHLIGHT
V
IN
PWR
VCC
MODE
SW
V
OUT
@ 1.8 A
LX1918
ON OFF
E/S
FB
PGND SGND
LX1918
LX1918
PACKAGE ORDER INFO
T
A
(擄C)
-40 to 85
LD
Plastic MLP
8-Pin 3x3mm
LX1918CLD
RoHS Compliant / Pb-free
Note: Available in Tape & Reel. Append the letters
鈥淭R鈥?to the part number.(i.e. LX1918CLD-TR)
Copyright
漏
2004
Rev. 1.1, 2005-07-05
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
1
2
3
4
5
6
7
8
9
