SC4521EVB-1

Manufacturer Part NumberSC4521EVB-1
DescriptionEVALUATION BOARD
ManufacturerSemtech
SC4521EVB-1 datasheet
 

Specifications of SC4521EVB-1

Silicon ManufacturerSemtechApplication Sub TypeStep Down Switching Regulator
Kit Application TypePower Management - Voltage RegulatorSilicon Core NumberSC4521
Lead Free Status / RoHS StatusLead free / RoHS Compliant  
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POWER MANAGEMENT
Description
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
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 SC4521 is an 600kHz switching regulator with a low
pin count.
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
2
2
V
V
IN
IN
5
5
Enable
Enable
8
8
C3
C3
C6
C6
Revision: October 5, 2007
3A Step-Down Switching Regulator
with Programmable Soft Start
Features
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
XDSL modems
CPE equipment
DC-DC point of load applications
Portable equipment
Digtial consumer electronics
C1
C1
1
1
BST
BST
3
3
IN
IN
SW
SW
6
6
SC4521
SC4521
EN
EN
FB
FB
7
7
SS
SS
COMP
COMP
D2
D2
GND
GND
4
4
C4
C4
R3
R3
1
SC4521
D1
D1
L1
L1
V
V
OUT
OUT
R1
R1
C2
C2
R2
R2
www.semtech.com

SC4521EVB-1 Summary of contents

  • Page 1

    ... Current mode control Precision enable threshold SO-8 EDP Lead-free package, fully WEEE and RoHS compliant Applications XDSL modems CPE equipment DC-DC point of load applications Portable equipment Digtial consumer electronics BST BST SC4521 SC4521 COMP COMP D2 D2 GND GND SC4521 OUT OUT www.semtech.com ...

  • Page 2

    ... Note: (1) ThetaJA is calculated from a package in still air, mounted to 3" x 4.5", 4 layer FR4 PCB with thermal vias under exposed pad per JESD51 standards. Electrical Characteristics Unless specified 12V 0.8V COMP BST -40°C to 125° 2007 Semtech Corp 5V tied open ° ° SC4521 ...

  • Page 3

    ... Notes: (1) The required minimum input voltage for a regulated output depends on the output voltage and load condition. (2) Guaranteed by design. (3) See Application Information. 2007 Semtech Corp 5V tied open < V < µ SC4521 www.semtech.com µ µ µ µ µ A µ A µ ...

  • Page 4

    ... POWER MANAGEMENT Pin Configurations TOP VIEW BST GND 4 5 (SOIC-8L-EDP) Pin Descriptions 2007 Semtech Corp. Ordering Information Notes: COMP (1) Only available in tape and reel packaging. A reel FB contains 2500 devices. EN (2) Lead free product. This product is WEEE and RoHS compliant SC4521 www.semtech.com ...

  • Page 5

    ... Block Diagram COMP COMP - - 1.6V INTERNAL SUPPLY 1.6V INTERNAL SUPPLY SS SS OSCILLATOR OSCILLATOR Typical Characteristic - OCP Limit 7 6.5 6 5.5 5 4.5 4 3 2007 Semtech Corp SLOPE SLOPE + + PWM PWM UVLO UVLO REFERENCE REFERENCE HICCUP HICCUP SLOPE SLOPE SLOPE COMP SLOPE COMP CLK ...

  • Page 6

    ... Overcurrent protection (OCP) is triggered when the current limit exceeds the upper limit of 3A, detected by a voltage on COMP greater than 2007 Semtech Corp. about 2V. When an OCP fault is detected, the switch is turned off and the external COMP capacitor is gradually discharged at the rate of dv/dt=3 the total capacitance value attached to COMP ...

  • Page 7

    ... The inductor value can be determined according to its operating point under its continuous mode and the switching frequency as follows: 2007 Semtech Corp. Where switching frequency, = ratio of the peak to peak inductor current to the output load current and V = output voltage ...

  • Page 8

    ... Boost Capacitor and its Supply Source Selection The boost capacitor selection is based on its discharge ripple voltage, worst case conduction time and boost current. The worst case conduction time T estimated as follows: 2007 Semtech Corp. Where the switching frequency and s Dmax = maximum duty ratio, 0.85 for the SC4521. ...

  • Page 9

    ... 2007 Semtech Corp. Where: R – Load and L C – Output capacitor. The goal of the compensation design is to shape the loop to have a high DC gain, high bandwidth, enough phase margin, and high attenuation for high frequency noises. Figure 3 gives a typical compensation network which ...

  • Page 10

    ... The following guidelines should be used to ensure proper operation of the converters ground plane is suggested to minimize switching noises and trace losses and maximize heat transferring. 2007 Semtech Corp. 2. Start the PCB layout by placing the power components so that the first. Arrange the power circuit to achieve a clean P1 power flow route ...

  • Page 11

    ... POWER MANAGEMENT Application Information (Cont.) Design Example 10u 10u Note: The bottom pad needs a big copper area to remove the heat 2007 Semtech Corp 0.22u 0.22u COMP COMP Css Css SC4521 SC4521 100n 100n C5 C5 560p 560p SC4521 =1V @2A =1V @ 3.9uH 3.9uH Co Co ...

  • Page 12

    ... POWER MANAGEMENT Application Information (Cont.) Design Example 2: 6.2V to 1. 10u Note: The bottom pad needs a big copper area to remove the heat 2007 Semtech Corp 0.22u COMP Css SC4521 100n C5 560p SC4521 L1 V =1.5V o 4.7uH Co R1 100u 8.66k C4 R2 18n 10k R3 4 ...

  • Page 13

    ... POWER MANAGEMENT Application Information (Cont.) Design Example 3: 13V ~ 21V to 3. 4.7u 4.7u 200k 200k Css Css 330n 330n Note: The bottom pad needs a big copper area to remove the heat 2007 Semtech Corp Rss Rss COMP COMP SC4521 SC4521 C5 C5 560p 560p ...

  • Page 14

    ... POWER MANAGEMENT Application Information (Cont.) Design Example 4: 13V ~ 21V 1. Rss Rss 4.7u 4.7u 200k 200k Css Css 470n 470n Note: The bottom pad needs a big copper area to remove the heat 2007 Semtech Corp 0.22u 0.22u COMP COMP SC4521 SC4521 C5 C5 560p 560p ...

  • Page 15

    ... POWER MANAGEMENT Application Information (Cont.) 2007 Semtech Corp. (PCB - TOP) (PCB - BOTTOM) 15 SC4521 www.semtech.com ...

  • Page 16

    ... POWER MANAGEMENT Application Information (Cont.) 2007 Semtech Corp. (Componet Side - TOP) (Componet Side - TOP) 16 SC4521 www.semtech.com ...

  • Page 17

    ... Outline Drawing - SOIC-8L EDP 2X E/2 ccc C 2X N/2 TIPS aaa C SEATING PLANE C EXPOSED PAD NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. DATUMS -A- 3. DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. 4. REFERENCE JEDEC STD MS-012, VARIATION BA. 2007 Semtech Corp DIM ...

  • Page 18

    ... REFERENCE IPC-SM-782A, RLP NO. 300A. 3. THERMAL VIAS IN THE LAND PATTERN OF THE EXPOSED PAD SHALL BE CONNECTED TO A SYSTEM GROUND PLANE. FAILURE MAY COMPROMISE THE THERMAL AND/OR FUNCTIONAL PERFORMANCE OF THE DEVICE. Contact Information Phone: (805)498-2111 FAX (805)498-3804 2007 Semtech Corp. E SOLDER MASK D DIM INCHES C ...