SC1182 Ver la hoja de datos (PDF) - Semtech Corporation

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SC1182

Programmable Synchronous DC/DC Converter, Dual LDO Controller

Semtech Corporation 

POWER MANAGEMENT

Block Diagram

SC1182 & SC1183

CS- CS+

VCC

EN

VID4

VID3

VID2

VID1

VID0

VOSENSE

PWRGOOD

OVP

LDOS1

GATE1

REF

70mV

+

-

CURRENT LIMIT

D/A

R

OSCILLATOR

Q

S

+

-

OPEN

COLLECTORS

+

-

VCC

+

-

FET

CONTROLLER

2.5V/ADJ.

-

+

+

-

ERROR

AMP

AGND

1.265V

REF

FET

CONTROLLER

1.5V/ADJ.

LEVEL SHIFT

AND HIGH SIDE

DRIVE

SHOOT

THRU

CONTROL

BSTH

DH

PGNDH

SYNCHRONOUS

DRIVE

BSTL

DL

PGNDL

AGND

LDOV

GATE2 LDOS2 AGND

Setting LDO Output Voltage.

For the SC1183, LDO Output voltages must be set by se-

lecting appropriate resistor values. These values may be

determined from the eqution below, or from the table at

right.

VOUT

=

1.265 ⋅ (RA

RB

+ RB ) + (IFB

⋅RA)

where :

IFB = Feedback pin bias current

RA = Top feedback resistor

RB = Bottom feedback resistor

See layout diagram for clarification

RA must be low enough so that the (IFB ⋅ RA ) term

does not cause significant error

VOUT LDO1 (LDO2)

3.45V

3.30V

3.10V

2.90V

2.80V

2.50V

1.50V

© 2001 Semtech Corp.

5

RB

RA

105Ω

105Ω

102Ω

100Ω

100Ω

100Ω

100Ω

182Ω

169Ω

147Ω

130Ω

121Ω

97.6Ω

18.7Ω

www.semtech.com

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