POWER MANAGEMENT
1
www.semtech.com
SC4518H
600kHz, 2A Step-Down
Switching Regulator
Description
Features
Typical Application Circuit
Applications
Revision: October 20, 2005
The SC4518H is a current mode switching regulator with
an integrated switch, operating at 600kHz with separate
sync and enable functions. The integrated switch allows
for cost effective low power solutions (peak switch current
2 amps). The sync function allows customers to
synchronize to a faster clock in order to avoid frequency
beating in noise sensitive applications. High frequency
of operation allows for very small passive components.
Current mode operation allows for fast dynamic response
and instantaneous duty cycle adjustment as the input
varies (ideal for CPE applications where the input is a
wall plug power).
The low shutdown current makes it ideal for portable
applications where battery life is important.
The SC4518H is a 600kHz switching regulator
synchronizable to a faster frequency from 750kHz to
1.2MHz.
Integrated 2 Amp switch
600kHz frequency of operation
Current mode controller
Synchronizable to higher frequency up to 1.2MHz
Precision enable threshold
SO-8 EDP package. Lead free product, fully WEEE
and RoHS compliant
XDSL modems
CPE equipment
DC-DC point of load applications
Portable equipment
C1
VOUT
D2
D1
R3
C2
L1
Enable
BST
1
IN
2
SW
3
GND
4
EN
5
FB
6
COMP
7
SYNC
8
VIN
C4
C3
SC4518H
R1
R2
2
2005 Semtech Corp.
www.semtech.com
POWER MANAGEMENT
SC4518H
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Electrical Characteristics
Unless specified: V
IN
= 12V, V
COMP
= 0.8V, V
BST
= V
IN
+ 5V, EN = tied to V
IN
, SYNC = 0, SW = open.
T
A
= T
J
= -40C to 125C.
Absolute Maximum Ratings
Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters
specified in the Electrical Characteristics section is not implied. Exposure to Absolute Maximum rated conditions for extended periods of time may
affect device reliability.
Notes:
(1) For proper operation of device, V
IN
should be within maximum Operating Input Voltage as defined in Electrical
Characteristics.
(2) Minimum pad size.
4
2005 Semtech Corp.
www.semtech.com
POWER MANAGEMENT
SC4518H
Electrical Characteristics
(Cont.)
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= 12V, V
COMP
= 0.8V, V
BST
= V
IN
+ 5V, EN = tied to V
IN
, SYNC = 0, SW = open.
T
A
= T
J
= -40C to 125C.
Notes:
(1) The device may not function properly outside its operating input voltage.
(2) The required input voltage for a regulated output depends on the output voltage and load condition.
(3) Guaranteed by design.
5
2005 Semtech Corp.
www.semtech.com
POWER MANAGEMENT
SC4518H
Pin Configurations
Ordering Information
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Notes:
(1) Only available in tape and reel packaging. A reel
contains 2500 devices.
(2) Lead free product. This product is fully WEEE and
RoHS compliant.
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Pin Descriptions
1
2
3
4
SYNC
BST
TOP VIEW
(SO-8 EDP)
5
6
7
8
COMP
IN
FB
SW
EN
GND
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