LTM4632

12

4632fc

For more information www.linear.com/LTM4632

In this case, multiple LTM4632s should be setup to oper-

ate 180 degrees, 120 degrees or 90 degrees shift which

corresponds to 2-phase, 3-phase or 4-phase operation

by letting SYNC/MODE of the LTM4632 synchronize to

an external multiphase oscillator like LTC6902.

APPLICATIONS INFORMATION

33.2k

3.3

PH

MOD

OUT1

0°

0°

180°

360°

180°

VDDQ

6A

VTT

6A

180°

OUT2

SET

SYNC/

MODE

SYNC/

MODE

DIV

GND

4632 F03

Figure 3. Example of Clock Phasing for 2-Phase

VDDQ Plus 2-Phase VTT Operation with LTC6902

Tie RUN1, TRACK/SS1 FB1 and COMP1 pin of each par-

alleling module together for VDDQ output. Tie RUN2,

together for VTT output. Figure 22 shows an example of

two LTM4632 get paralleled to provide 6A VDDQ and 6A

VTT termination supply.

Input and Output RMS Ripple Current Cancellation

A multiphase power supply significantly reduces the

amount of ripple current in both the input and output

capacitors. The RMS input ripple current is reduced by,

and the effective ripple frequency is multiplied by, the

number of phases used (assuming that the input volt-

age is greater than the number of phases used times

the output voltage). The output ripple amplitude is also

reduced by the number of phases used when all of the

outputs are tied together to achieve a single high output

current design.

0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9

0.60

0.55

0.50

0.45

0.40

0.35

0.30

0.25

0.20

0.15

0.10

0.05

0

4632 F04

6-PHASE

4-PHASE

3-PHASE

2-PHASE

1-PHASE

Figure 4. Input RMS Current Ratios to DC Load Current as a Function of Duty Cycle