LTC1876 View Datasheet(PDF) - Linear Technology

Part Name

Description

MFG CO.

LTC1876

High Efficiency, 2-Phase, Dual Synchronous Step-Down Switching Controller and Step-Up Regulator

Linear Technology 

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LTC1876

APPLICATIO S I FOR ATIO

PC Board Layout Checklist

When laying out the printed circuit board, the following

checklist should be used to ensure proper operation of the

LTC1876. These items are also illustrated graphically in

the layout diagram of Figure 15. The Figure 16 illustrates

the current waveforms present in the various branches of

the 2-phase synchronous regulators operating in the

continuous mode. Check the following in your layout:

1. Are the top N-channel MOSFETs M1 and M3 located

within 1cm of each other with a common drain connection

at CIN? Do not attempt to split the input decoupling for the

two channels as it can cause a large resonant loop.

2. Is the ground of the step-down controller kept separate

from the ground of the step-up regulator? The regulator

ground should join the controller ground at the combined

COUT (–) plates. Within the controller circuitry, are the

signal and power grounds kept separate? The controller

R1

R3

VOUT3

COUT3

R2

INTVCC

1

RUN/SS1

36

PGOOD

2 SENSE1+

35

TG1

3 SENSE1–

34

SW1

4

VOSENSE1

5

FREQSET

6

STBYMD

33

BOOST1

32

VIN

31

BG1

7

FCB

8

ITH1

30

EXTVCC

LTC1876

29

INTVCC

9

SGND

28

PGND

VPULL-UP

(<7V)

CB1

CINTVCC

RIN

CVIN

VIN

10

3.3V

3.3VOUT

27

BG2

11

ITH2

26

BOOST2

12

25

CB2

VOSENSE2

SW2

R4

13 SENSE2–

24

TG2

14 SENSE2+

23

RUN/SS2

R7

15

AUXSGND

22

AUXSD

SHUTDOWN

16

AUXVFB

21

AUXVIN

17

20

R8

AUXSW

AUXPGND

CAUXIN

18

AUXSW

19

AUXPGND

D3

L3

L1 3 RSENSE 4

1

2

M1

M2

D1

COUT1

CIN

COUT2

M3

M4

D2

1 RSENSE 2

L2 3

4

VOUT1

VOUT2

30

1876 F15

Figure 15. LTC1876 Recommended Printed Circuit Layout Diagram

1876fa

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