21

LTC3720

3720f

APPLICATIO S I FOR ATIO

Figure 8. 15A CPU Core Voltage Regulator with Active Voltage Positioning at 300kHz

100mV/DIV

1.5V

10A/DIV

3720 F09

FIGURE 7 CIRCUIT

Figure 10. Transient Response with Active

100mV/DIV

1.5V

10A/DIV

3720 F10

FIGURE 8 CIRCUIT

1

2

3

4

5

6

7

8

9

10

11

12

13

14

28

27

26

25

24

23

22

21

20

19

18

17

16

15

RUN/SS

PGOOD

FCB

SGND

SGND

VID0

VID1

BOOST

TG

SW

PGND

BG

VID4

VID3

VID2

LTC3720

330k

100k

0.01

µF

40.2k

0.1pF

0.1

µF

POWER GOOD

+

1.05V TO 1.825V

15A

5V TO 24V

270

µF

2V

×3

10

µF

35V

×3

SGND

3720 F08

CMDSH-3

M1

IRF7811A

M2

IRF7811A

×2

4.7

µF

6.3V

UPS840

0.003

Ω

1

Ω

100pF

4.99k

45.3k

L1

1

µH

+

The modified circuit is shown in Figure 8. Figures 9 and 10

show the transient response without and with active

voltage positioning. Both circuits easily stay within

±100mV

of the 1.5V output. However, the circuit with active voltage

positioning accomplishes this with only three output ca-

pacitors rather than five. Refer to Linear Technology

Design Solutions 10 for additional information about

active voltage positioning.