SC2441A Datasheet, PDF(1/37 Page) Semtech Corporation – 1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter

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SC2441A Datasheet, PDF (1/37 Pages) Semtech Corporation – 1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter

SC2441A

1.8V to 20V Input 2-Phase Synchronous

Step-down Controllers with Step-up Converter

POWER MANAGEMENT

Description

The SC2441A is a programmable frequency dual

independent or dual/multiple phase single output peak

current-mode step-down switching regulator controller. It

is capable of operating from 1.8V to 20V input. A 0.6A

step-up converter in the SC2441A generates an auxiliary

gate drive supply when VIN is below 4.5V. This makes the

SC2441A well suited for applications where a low-voltage

input (<3.3V) is to be stepped down for lower voltage logic,

yet the input is too low to drive power MOSFETs

efficiently.

The SC2441A employs a phase-locked synchronizing

circuit that allows the step-up converter to operate at

twice the switching frequency of the step-down

controllers for miniaturization. The clock output signal

enables two or more SC2441As to be daisy chained with

programmable phase shift.

Tying the FB2 pin to VIN makes the second step-down

channel a slave of the first. Operating in this mode, the

SC2441A regulates a single output with shared current in

each channel. Each step-down controller has its own soft-

start and overload shutdown timer for hiccup overload

protection. In the single-output mode, the channel 1 timer

controls the soft-start and overload hiccup of both

controllers.

Typical Application Circuit

Features

2-Phase Synchronous Step-down Controllers

u 2-Phase Synchronous Continuous Conduction Mode

u Out of Phase Operation for Low Input Current Ripple

u Operates up to 1MHz Per Channel

u Excellent Current Sharing Between Phases

u Duty Cycle Up to 90%

u 0.5V Feedback voltages for Low-Voltage Outputs

u Starts into Pre-biased Outputs

u Adaptive Shoot-through Protection

u Lossless Inductor DCR Current Sensing

u 23mV Current-limit Threshold

u Individual Soft-start, Overload Hiccup and Enable

Step-up Regulator

u 0.27V VCESAT Switch at 0.6A

u Fixed frequency Current-mode Control

Common Features

u Wide input Voltage Range: 1.8V to 20V

u Synchronizing Frequency Equal to that of the Step-

down Converters

u 28-lead TSSOP-EDP Lead-free package, fully WEEE

and RoHS compliant

Applications

u Low voltage distributed DC-DC converters

u Telecommunication power supplies

u Servers and base stations

Vin

VOU T1

C13

R10

R 15

RCS+1

R19

Signal

Ground

Power

Ground

Revision: March 7, 2006

VCC

R 11

C19

1 IN

27 SW3

21 VCC

25 BST1

23 GDH1

22 GDL1

24 PGND1

26 PGND2

4 CS1+

5 CS1-

11 FB1

12 COMP1

FB3 7

COMP3 8

CKOUT 28

BST2 18

GDH2 19

GDL2 20 R12

PLLF 2

CS2+ 16

CS2- 15

FB2 14

COMP2 13

C 20

R13

R20

C21

C22

R21

C11

RCS+2

10 ROSC SYNC/SHDN 6

R25

SS1/EN1 3

Vin

R26

9 GND

SS2/EN2 17

C26 R27

C25

SC2441A

VCC

C 23

R23

R24

C24

VOUT2

C12

R16

R18

Figure 1

www.semtech.com

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