Low-Cost, Dual-Output, Step-Down

Controller with Fast Transient Response

______________________________________________________________________________________

13

FB1

IN

PWRGD

VL

GND

OSC/EN12

REFIN2

ILIM2

FB2

ILIM1

DH1

LX1

BST1

DL1

PGND

DH2

LX2

BST2

DL2

VCC

INPUT

10V TO 14V

POWER-GOOD

TO SYSTEM

ENABLE

OUT1

1.8V/20A

OUT2

0.9V/6A

C5

1

μF

C6

1

μF

C13

4.7

μF

R9

10k

Ω

C1

0.01

μF

R1

3.16k

Ω

C2

10

μF

C8

0.015

μF

R3

10k

Ω

R4

3.57k

Ω

L1

0.56

μH

C15

0.01

μF

L2

0.47

μH

R13

10k

Ω

C19

4700pF

N1

N5

R2

24.3k

Ω

R11

14.7k

Ω

R5

3

Ω

N7

2N7002

OUT1

R7

1k

Ω

R6

1k

Ω

C12

1000pF

R10

44.2k

Ω

ON

OFF

C7

0.22

μF

C18

0.22

μF

C14

2200pF

C3

10

μF

C4

1000

μF

C16

10

μF

C17

10

μF

C11

10

μF

C9

470

μF

C10

470

μF

C22

10

μF

C20

680

μF

C21

680

μF

N6

N2

N3

N4

R8

2.74k

Ω

MAX8664

R12

2

Ω

C23

2200pF

Figure 3. 500kHz Tracking Circuit for DDR2 Applications