LT8644S

20

Rev. 0

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APPLICATIONS INFORMATION

Temperature rise of the LT8644S is worst when operating

the case temperature is too high for a given application,

be decreased to reduce the temperature to an acceptable

level. Figure 8 shows examples of how case temperature

rise can be managed by reducing switching frequency

or load.

The LT8644S’s top switch current limit decreases with

higher duty cycle operation for slope compensation. This

also limits the output current the LT8644S can deliver

for a given application. See curve in Typical Performance

Characteristics.

Figure 8. Case Temperature Rise

Figure 9. 2MHz 1.2V, 16A Step-Down Converter with Soft-Start and Power Good

TYPICAL APPLICATIONS

PINS NOT USED IN

THIS CIRCUIT:

PHMODE

LT8644S

SW

FB

2.7V TO 8V

GND

RT

EN/UV

1.2V

16A

220µF ×2

1206

X5R/X7R

22µF

100k

100k

L: XEL5030

SS

10nF

PG

SYNC/MODE

CLKOUT

100k

8644S F09

33pF

16.9k

0.13µH

13.3k

390pF

DEMO BOARD ON STILL AIR

Burst Mode OPERATION

1MHz

2MHz

3MHz

LOAD CURRENT (A)

0

2

4

6

8

10

12

14

16

0

10

20

30

40

50

60

70

8644S F08

Figure 10. 2MHz 1V, 16A Step-Down Converter with Spread Spectrum

47pF

PINS NOT USED IN

THIS CIRCUIT:

BST, CLKOUT, PG, SS,

PHMODE

LT8644S

SW

FB

GND

RT

1V

16A

220µF ×2

1206

X5R/X7R

22µF

16.9k

100k

150k

0.13µH

L: XEL5030

SYNC/MODE

2.7V TO 8V

EN/UV

8644S F10

12.1k

470pF