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Número de pieza | SC4521 | |
Descripción | 3A Step-Down Switching Regulator | |
Fabricantes | Semtech Corporation | |
Logotipo | ||
Hay una vista previa y un enlace de descarga de SC4521 (archivo pdf) en la parte inferior de esta página. Total 18 Páginas | ||
No Preview Available ! SC4521
3A Step-Down Switching Regulator
with Programmable Soft Start
POWER MANAGEMENT
Description
Features
The SC4521 is a current mode switching regulator with
an integrated switch, operating at 600kHz with
programmable soft start and enable functions. The
integrated switch allows for cost effective low power
solutions (peak switch current 3 amps). High frequency
operation allows for very small passive components.
Current mode operation allows for fast dynamic response
and instantaneous duty cycle adjustment as the input
www.DatavwSahaerlieletp4sUlu.(cgidompeoawl feorr). CPE applications where the input is a
Wide operating voltage range: 4.4V to 24V
Integrated 3 Amp switch
600kHz frequency of operation
Programmable soft start funchion
Current mode control
Precision enable threshold
SO-8 EDP Lead-free package, fully WEEE and RoHS
compliant
Applications
The low shutdown current makes it ideal for portable
applications where battery life is important.
The SC4521 is an 600kHz switching regulator with a low
pin count.
XDSL modems
CPE equipment
DC-DC point of load applications
Portable equipment
Digtial consumer electronics
The SC4521 allows customers to use large capacitive
loads because its programmable soft start limits the dv/
dt of the output at start up.
Typical Application Circuit
D1
VIN
Enable
C3
2
IN
5
EN
8
SS
C6
1
BST
3
SW
SC4521
6
FB
GND
4
7
COMP
C4
R3
C1
L1
D2
VOUT
R1
C2
R2
Revision: October 5, 2007
1
www.semtech.com
1 page POWER MANAGEMENT
Block Diagram
SC4521
+
+
SLOPE
Is
+
ISEN
IN
40m
www.DataSheet4U.com
COMP
FB
-
EA
+
PW M
SQ
R
EN REFERENCE UVLO
1.6V INTERNAL SUPPLY
SS SLOPE
SLOPE COMP
OSCILLATOR
FREQUENCY
CLK
Is
HICCUP
FB
BST
POWER
TRANSISTOR
SW
OL GND
Typical Characteristic - OCP Limit
SC4519H OCP Limit vs Duty Cycle
7
6.5
6
5.5
5
4.5
4
3.5
3
2.5
2
0
20 40 60 80 100
Duty Cycle (%)
2007 Semtech Corp.
5
ILIM @-40C
ILIM @25C
ILIM @125C
www.semtech.com
5 Page POWER MANAGEMENT
Application Information (Cont.)
Design Example 1: 5V to 1V at 2A
SC4521
VI = 5V
R0
0 C3
10u
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D1
Css
100n
2 IN
5 EN
8 SS
SW 3
FB 6
COMP 7
SC4521
C5
560p
C1
0.22u
C4
18n
R3
20k
L1
3.9uH
R1
2.49k
Vo=1V @2A
Co
470u
R2
10k
D2
Note: The bottom pad needs a big copper area to remove the heat.
Bill of Materials
Item
Qty
Reference
Value
1 1 C1
0.22uF, 25V, 0805, X7R
2 1 Co
470uF, 10V, ZA
3 1 C3
10uF
4 1 C4
18nF, 0805, X7R, 25V
5 1 C5
560pF, 50V, 0805
6 1 D1
1N4148SW, SOD323
7 1 D2
EC30LA02
8 1 L1
3.9uH
9 1 R0
0, 0805
10 1 R1
2.49k, 1%, 0805
11 1 R2
10k, 1%, 0805
12 1 R3
20k, 1%, 0805
13 - R4
not used, 0805
14 1 Css
100nF
15 1 U1
SC4521
Unless specified, all resistors have 1% precision with 0805 package.
Resistors are +/-1% and all capacitors are +/-20%
2007 Semtech Corp.
11
Part No./Manufacturer
Vishay: VJ0805Y224KXX
Rubicon
TDK: C3216OJ106MT
Vishay
Vishay
Nihon Inter Electronics Corp.
Sumida: RCR875DNP-3R9L
SMTZONE
Semtech
www.semtech.com
11 Page |
Páginas | Total 18 Páginas | |
PDF Descargar | [ Datasheet SC4521.PDF ] |
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