SC4525CSETRT

Manufacturer Part NumberSC4525CSETRT
DescriptionIC BUCK ADJ 3A 8SOIC
ManufacturerSemtech
Series-
TypeStep-Down (Buck), PWM - Current Mode
SC4525CSETRT datasheet
 

Specifications of SC4525CSETRT

Internal Switch(s)YesSynchronous RectifierNo
Number Of Outputs1Voltage - Output1 V ~ 26.88 V
Current - Output3AFrequency - Switching300kHz ~ 1.3MHz
Voltage - Input3 V ~ 28 VOperating Temperature-40°C ~ 105°C
Mounting TypeSurface MountPackage / Case8-SOIC (0.154", 3.90mm Width) Exposed Pad
Lead Free Status / Rohs StatusLead free / RoHS CompliantOther namesSC4525CSETR
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POWER MANAGEMENT
Features
Wide input range: 3V to 28V
3A Output Current
200kHz to 2MHz Programmable Frequency
Precision 1V Feedback Voltage
Peak Current-Mode Control
Cycle-by-Cycle Current Limiting
Hiccup Overload Protection with Frequency Foldback
Soft-Start and Enable
Thermal Shutdown
Thermally Enhanced 8-pin SOIC Package
Fully RoHS and WEEE compliant
Applications
XDSL and Cable Modems
Set Top Boxes
Point of Load Applications
CPE Equipment
DSP Power Supplies
LCD and Plasma TVs
Typical Application Circuit
10V – 28V
V IN
C4
4.7mF
BST
IN
SC4525C
SS/EN
COMP
ROSC
GND
C7
R5
R7
C8
15.8k
12.7k
22nF
22pF
C5
2.2nF
L1: Coiltronics CD1- 5R2
Figure 1. 1MHz 10V -28V to 5V/3A Step-down Converter
Jan. 13, 2011
28V 3A Step-Down Switching Regulator
Description
The SC4525C is a constant frequency peak current-mode
step-down switching regulator capable of producing 3A
output current from an input ranging from 3V to 28V. The
switching frequency of the SC4525C is programmable
up to 2MHz, allowing the use of small inductors and
ceramic capacitors for miniaturization, and high input/
output conversion ratio. The SC4525C is suitable for
next generation XDSL modems, high-definition TVs and
various point of load applications.
Peak current-mode PWM control employed in the
SC4525C achieves fast transient response with simple loop
compensation. Cycle-by-cycle current limiting and hiccup
overload protection reduces power dissipation during
output overload. Soft-start function reduces input start-
up current and prevents the output from overshooting
during power-up.
The SC4525C is available in SOIC-8 EDP package.
SC4525A
D1
1N4148
C1
0.33mF
L1
OUT
SW
5.2mH
5V/3A
R4
33.2k
FB
D2
R6
C2
20BQ030
8.25k
10mFX3
C2: Murata GRM31CR60J106K
C4: Murata GRM32ER71H475K
Efficiency of the 1MHz 10V-28V to 5V/3A Step-Down Conve
SC4525C
Efficiency
90
80
V
= 24V
IN
V
= 12V
IN
70
60
50
40
0.0
0.5
1.0
1.5
2.0
2.5
Load Current (A)
3.0
1

SC4525CSETRT Summary of contents

  • Page 1

    POWER MANAGEMENT Features Wide input range 28V  3A Output Current  200kHz to 2MHz Programmable Frequency  Precision 1V Feedback Voltage  Peak Current-Mode Control  Cycle-by-Cycle Current Limiting  Hiccup Overload Protection with Frequency Foldback  ...

  • Page 2

    ... GND Pin SOIC - EDP) Marking Information yyww=Date code (Example: 0752) xxxxx=Semtech Lot No. (Example: E9010) Ordering Information Device SC4525CSETRT BST SC4525CEVB FB Notes: COMP (1) Available in tape and reel only. A reel contains 2,500 devices. (2) Available in lead-free package only. Device is fully WEEE and RoHS SS/EN compliant and halogen-free ...

  • Page 3

    Absolute Maximum Ratings V Supply Voltage ……………………………… -0.3 to 32V IN BST Voltage ……………………………………………… 42V BST Voltage above SW …………………………………… 34V SS Voltage ……………………………………………-0 Voltage …………………………………………… -0 Voltage ………………………………………… -0 Transient ...

  • Page 4

    Electrical Characteristics (Cont.) Unless otherwise noted 12V 15V BST Parameter Minimum Switch On-time Minimum Switch Off-time Switch Leakage Current Minimum Bootstrap Voltage BST Pin Current Oscillator Switching Frequency Foldback Frequency Soft Start and Overload ...

  • Page 5

    Pin Descriptions SO-8 Pin Name Pin Function Emitter of the internal NPN power transistor. Connect this pin to the inductor, the freewheeling diode and the 1 SW bootstrap capacitor. Power supply to the regulator also the collector of ...

  • Page 6

    Block Diagram COMP FREQUENCY FOLDBACK ROSC OSCILLATOR SS/ 1.9V REFERENCE & THERMAL SHUTDOWN SS/EN SS/EN FAULT FAULT Figure 3. Soft-start and Overload Hiccup Control Circuit ...

  • Page 7

    Eff Typical Characteristics Efficiency =3. =2. =1. 1MHz, V =12V Curve =B320A 0.5 ...

  • Page 8

    Curve 11 Typical Characteristics (Cont.) SS270 REV 6-7 V Thresholds vs Temperature IN 3.0 2.9 Start 2.8 2.7 2.6 Curve 14 UVLO 2.5 2.4 -50 - Temperature ( SS270 REV 6-7 V Quiescent Current vs V ...

  • Page 9

    Applications Information Operation The SC4525C is a constant-frequency, peak current-mode, step-down switching regulator with an integrated 28V, 3.9A power NPN transistor. Programmable switching frequency makes the regulator design more flexible. With the peak current-mode control, the double reactive poles of ...

  • Page 10

    Applications Information (Cont.) becomes armed. As the load draws more current from the regulator, the current-limit comparator ILIM (Figure 2) will eventually limit the switch current on a cycle-by- cycle basis. The over-current signal OC goes high, setting the latch ...

  • Page 11

    Applications Information (Cont.) Closed-loop measurement shows that the SC4525C minimum on time is about 120ns at room temperature (Figure 4). If the required switch on time is shorter than the minimum on time, the regulator will either skip cycles or ...

  • Page 12

    Applications Information (Cont.) resulting in very low ripple current. Avoid using Z5U and Y5V ceramic capacitors for output filtering because these types of capacitors have high temperature and high voltage coefficients. Freewheeling Diode Use of Schottky barrier diodes as freewheeling ...

  • Page 13

    Applications Information (Cont     − − BST   − − ...

  • Page 14

    Applications Information (Cont.) The high frequency pole nulls the ESR zero and attenuates high frequency noise Fz1 Fz1 -30 -30 -60 - 10K 10K 100K 100K FREQUENCY (Hz) ...

  • Page 15

    Applications Information (Cont.) Table 4. Typical switching time Input Voltage Input Voltage 1A 1A 12V 12V 12.5ns 12.5ns 24V 24V 22ns 22ns 28V 28V 25.3ns 25.3ns + + addition, the quiescent current loss is BST ...

  • Page 16

    Recommended Component Parameters in Typical Applications Table 5 lists the recommended inductance (L voltages. The inductance is determined by assuming that the ripple current is 35% of load current I parameters are calculated by assuming a 47mF low ESR ceramic ...

  • Page 17

    Typical Application Schematics 24V 4.7mF Coiltronics DR74- 6R8 Figure 10. 300kHz 24V to 1.5V/3A Step-down Converter 10V – 26V 4.7m F Fig10 : 300 kHz 1.5V/3 ...

  • Page 18

    Typical Performance Characteristics (For A 12V to 5V/3A Step-down Converter with 1MHz Switching Frequency) SS270 REV 6-7 Load Characteristic 0.5 1 1.5 2 2.5 Load Current (A) Figure 12(a). Load Characteristic 5V ...

  • Page 19

    Outline Drawing - SOIC-8 EDP N 2X E/2 1 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- AND 3. DIMENSIONS "E1" AND "D" ...

  • Page 20

    Land Pattern - SOIC-8 EDP (C) F THERMAL VIA P Ø 0.36mm NOTES: 1. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. 2. REFERENCE IPC-SM-782A, RLP NO. 300A. ...

  • Page 21

    ... PLICATIONS IS UNDERSTOOD TO BE UNDERTAKEN SOLELY AT THE CUSTOMER’S OWN RISK. Should a customer purchase or use Semtech products for any such unauthorized application, the customer shall indemnify and hold Semtech and its officers, em- ployees, subsidiaries, affiliates, and distributors harmless against all claims, costs damages and attorney fees which could arise. ...