LTM4623

11

4623fa

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.

The LTM4623 device is an inherently current mode con-

trolled device, so parallel modules will have very good

current sharing. This will balance the thermals on the

design. Please tie the RUN, TRACK/SS, FB and COMP pins

of each paralleling module together. Figure 26 shows an

example of parallel operation and pin connection.

Input RMS Ripple Current Cancellation

Application Note 77 provides a detailed explanation of

multiphase operation. The input RMS ripple current can-

cellation mathematical derivations are presented, and a

graph is displayed representing the RMS ripple current

reductionasafunctionofthenumberofinterleavedphases.

Figure 3 shows this graph.

applicaTions inForMaTion

Figure 2. 4-Phase, 6-Phase Operation

Figure 3. RMS Input Ripple Current to DC Load Current Ratio as a Function of Duty Cycle

0.75 0.8

4623 F03

0.7

0.65

0.6

0.55

0.5

0.45

0.4

0.35

0.3

0.25

0.2

0.15

0.1

0.85 0.9

0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

1 PHASE

2 PHASE

3 PHASE

4 PHASE

6 PHASE

4623 F02

CLKIN

PHMODE

CLKOUT

0

90

180

270

+90

+90

+90

PHASE 4

PHASE 3

PHASE 2

PHASE 1

CLKIN

PHMODE

CLKOUT

CLKIN

PHMODE

CLKOUT

CLKIN

PHMODE

CLKOUT

CLKIN

PHMODE

CLKOUT

120

240

(420)

60

180

+120

+180

+120

PHASE 4

PHASE 2

PHASE 5

PHASE 3

CLKIN

PHMODE

CLKOUT

CLKIN

PHMODE

CLKOUT

CLKIN

PHMODE

CLKOUT

300

+120

PHASE 6

CLKIN

PHMODE

CLKOUT

0

PHASE 1

CLKIN

PHMODE

CLKOUT

+120