SC4525DSETRT

Manufacturer Part NumberSC4525DSETRT
DescriptionIC BUCK ADJ 3A 8SOIC
ManufacturerSemtech
Series-
TypeStep-Down (Buck), PWM - Current Mode
SC4525DSETRT datasheet
 


Specifications of SC4525DSETRT

Internal Switch(s)YesSynchronous RectifierNo
Number Of Outputs1Voltage - Output1 V ~ 16.74 V
Current - Output3AFrequency - Switching65kHz ~ 350kHz
Voltage - Input3 V ~ 18 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 namesSC4525DSETR
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POWER MANAGEMENT
Features
Input range: 3V to 18V
3A Output Current
350kHz Fixed Switching 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
10 V – 16V
V
IN
C4
10mF
BST
IN
SW
SC4525D
SS/ EN
FB
COMP
RSET
GND
C7
R7
R5
C8
11.5k
60.4 k
22 nF
47 pF
C5
2.2 nF
L1 : Coiltronics CD1- 100
C2 : Murata GRM 31CR60J 476 M
C4 : Murata GRM 31CR61E 106 K
Figure 1. 350kHz 10V -16V to 5V/3A Step-down Converter
Jan. 13, 2011
Fig.1a : 350 kHz 10V - 16 V to 5V/3 A Step -
18V, 3A, 350kHz Step-Down
Description
The SC4525D is a 350kHz constant frequency peak
current-mode step-down switching regulator capable of
producing 3A output current from an input ranging from
3V to 18V. The SC4525D is suitable for next generation
XDSL modems, high-definition TVs and various point of
load applications.
Peak current-mode PWM control employed in the
SC4525D 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 SC4525D is available in SOIC-8 EDP package.
Fig.1b: 350kHz 10-16V to 5V/3A Step-Down Converter (Front Page Efficien
SC4525A
D1
1 N 4148
C1
0. 33 mF
L1
OUT
10 mH
5V/3A
R4
33.2k
D2
R6
C2
20BQ030
8.25k
47mF
Efficiency of the 1MHz 10V-28V to 5V/3A Step-Down Converter (Front Pag
Down Converter ( Front Page Schematic
SC4525D
Switching Regulator
Efficiency
90
85
80
V
=12V
IN
75
70
65
60
55
50
45
40
0
0.5
1
1.5
2
2.5
Load Current (A)
www.semtech.com
12 12
3
1
)

SC4525DSETRT Summary of contents

  • Page 1

    ... Fig.1b: 350kHz 10-16V to 5V/3A Step-Down Converter (Front Page Efficien SC4525A 4148 OUT 10 mH 5V/3A R4 33. 20BQ030 8.25k 47mF Efficiency of the 1MHz 10V-28V to 5V/3A Step-Down Converter (Front Pag Down Converter ( Front Page Schematic SC4525D Switching Regulator Efficiency =12V 0.5 1 1.5 2 2.5 Load Current (A) www.semtech.com ...

  • Page 2

    ... Pin SOIC - EDP) Marking Information yyww=Date code (Example: 0752) xxxxx=Semtech Lot No. (Example: E9010) © 2011 Semtech Corp. Ordering Information Device SC4525DSETRT BST SC4525DEVB 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

    ... COMP Source Current COMP Sink Current Internal Power Switch Switch Current Limit Switch Saturation Voltage © 2011 Semtech Corp. Thermal Information Junction to Ambient Junction to Case Maximum Junction Temperature……………………… 150°C Storage Temperature ………………………… -65 to +150°C Lead Temperature (Soldering) 10 sec … ...

  • Page 4

    ... Hiccup Arming SS/EN Voltage Hiccup SS/EN Overload Threshold Hiccup Retry SS/EN Voltage Over Temperature Protection Thermal Shutdown Temperature Thermal Shutdown Hysteresis Note 1: Switch current limit does not vary with duty cycle. © 2011 Semtech Corp. = 2.2V, -40°C < < 125° 60.4kΩ ...

  • Page 5

    ... V The exposed pad serves as a thermal contact to the circuit board soldered to the ground plane of the 9 Exposed Pad PC board. © 2011 Semtech Corp. falls below 0.8V, then the switching frequency will be reduced order to fully enhance the internal NPN power transistor. IN SC4525D www ...

  • Page 6

    ... V1 V1 FREQUENCY FREQUENCY FOLDBACK FOLDBACK ROSC ROSC SS/EN SS/ REFERENCE REFERENCE & THERMAL & THERMAL SHUTDOWN SHUTDOWN SS/EN SS/EN FAULT FAULT Figure 3. Soft-start and Overload Hiccup Control Circuit © 2011 Semtech Corp. SLOPE SLOPE + + COMP COMP PWM PWM - - OSCILLATOR OSCILLATOR 1.2V 1. ...

  • Page 7

    ... SS270 REV 6-7 Switch Saturation Voltage vs Switch Current 500 450 o 400 125 350 300 o 250 25 C 200 150 100 50 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 Switch Current (A) © 2011 Semtech Corp. (3) 3.3Vin Eff SC4525B Efficiency (6) Foldback Freq vs Temp ...

  • Page 8

    ... Temperature ( V Quiescent Current 2.5 o 125 C 2.0 o -40 1.5 1.0 0.5 0 (V) IN © 2011 Semtech Corp. Curve 12 SS270 REV 6-7 V Supply Current IN vs Soft-Start Voltage 2.5 125 2.0 o -40 1.5 1.0 (15) SS charge cur vs SS volt 0.5 0 100 125 V (V) ...

  • Page 9

    ... Pulling the SS/EN pin below 0.2V shuts off the regulator and reduces the input supply current to 18µA (V When the SS/EN pin is released, the soft-start capacitor © 2011 Semtech Corp. is charged with an internal 1.9µA current source (not shown in Figure 3). As the SS/EN voltage exceeds 0.4V, ...

  • Page 10

    ... ⋅ ⋅ ⋅ ⋅ © 2011 Semtech Corp ⋅ ⋅ − − where V voltage, and V diode. In peak current-mode control, the PWM modulating ramp is the sensed current ramp of the power switch. will recharge This current ramp is absent unless the switch is turned C on ...

  • Page 11

    ...   input capacitance can be estimated from > > ⋅ D ⋅ ⋅ ⋅ © 2011 Semtech Corp. > > ⋅ D ⋅ ⋅ ⋅ where − − Multi-layer ceramic capacitors, which have very low ESR (a few mW) and can easily handle high RMS ripple current, are ...

  • Page 12

    ... Temperature ( Temperature ( Figure 5. Typical Minimum Bootstrap Voltage required to Saturate the Transistor (I © 2011 Semtech Corp. For the bootstrap circuit, a fast switching PN diode (such as 1N4148 or 1N914) and a small (0.33µF – 0.47µF) ceramic capacitor is sufficient for most applications. When bootstrapping from 2.5V to 3.0V output voltages, use a ...

  • Page 13

    ... ≈ ≈ PWM PWM ⋅ ⋅ PWM PWM ⋅ ⋅ ESR zero © 2011 Semtech Corp ⋅ π ⋅ π ⋅ ⋅ ⋅ ⋅ ⋅ ⋅ 600 600 ⋅ π ⋅ π ⋅ ⋅ ⋅ ⋅ PWM PWM ESR ...

  • Page 14

    ... C C − − 18.5 18.5 ⋅ ⋅ ⋅ ⋅ ⋅ π ⋅ π ⋅ ⋅   Then the compensator parameters are © 2011 Semtech Corp.       ⋅ ⋅     ⋅ ...

  • Page 15

    ... The exposed pad should be soldered to a large ground plane as the ground copper acts as a heat sink for the device. To ensure proper adhesion to the ground plane, avoid using vias directly under the device. © 2011 Semtech Corp. (13 ⋅ ...

  • Page 16

    ... Table 4. Recommended inductance (L Typical Applications Vin(V) Vo(V) Io(A) 1.0 3.3 2.0 1.5 5 2.5 3.3 1.5 2.5 12 3.3 5 7.5 © 2011 Semtech Corp. ) and compensation network ( and compensator (R 1 Recommended Parameters C2(uF) L1(uH) R7(k) 3.3 3.74 2.2 6.49 3.3 3.74 4.7 6.49 4.7 7 ...

  • Page 17

    ... L1 : CoiltronicsDR73 - 4R7 Figure 10. 350kHz 5V to 2.5V/3A Step-down Converter 3. 4.7mF Fig. 10: 350 kHz 2.5V/3 A Step Down Converte SS/EN COMP Coiltronics DR73 - 3R3 Figure 11. 350kHz 3.3V to 1.5V/3A Step-down Converter © 2011 Semtech Corp. C1 0.33m F BST IN SW SC4525D FB RSET GND 60.4k 6.49 k CMSH3 - 20M C5 4 ...

  • Page 18

    ... Load Current (A) Figure 12(a). Load Characteristic 5V Output Response (1V/DIV, AC Coupling) Inductor Current (1A/DIV) 40us/DIV Figure 12(c). Load Transient Response (I = 0.3A to 3A) O © 2011 Semtech Corp. Fig.12b: SS 12V Input (5V/DIV) 5V Output (2V/DIV) SS Voltage (1V/DIV) 3 3.5 4 Fig.12d: OCP Figure 12(b). V Figure 12(d). Output Short Circuit (Hiccup) ...

  • Page 19

    ... N/2 TIPS aaa C SEATING PLANE C EXPOSED PAD NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). -A- 2. DATUMS AND 3. DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. REFERENCE JEDEC STD MS -012, VARIATION BA. 4. © 2011 Semtech Corp e bxN bbb C A-B D ...

  • Page 20

    ... CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. 2. 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. © 2011 Semtech Corp. E SOLDER MASK D DIM ...

  • 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. ...