7

FN9144.4

June 6, 2005

Rs1

2.0K

Rs2

2.0K

Q1

Lo1

Co11

4.7µF

D2

BAT54W

Rbt1

Lo2

Q2

10µF

Co21

220µF

Co22

4.7µF

Rset1

100K

Csoft1

10K

Cfb1

0.01 F

SOFT1

PG1

OCSET1

EN1

GND

VSEN1

PGND1

LGATE1

ISEN1

PHASE1

UGATE1

BOOT1

GND

VCC

VIN

PGND2

LGATE2

ISEN2

PHASE2

UGATE2

BOOT2

GND

PG2

SOFT2

V1 (2.5V)

V2 (1.8V)

DDR

EN2

VCC (5V)

U1

FDS6912A

FDS6912A

4.7µH

Cin1

10µF

Cdc

D1

BAT54W

0

Ω

Cbt2

Rbt2

0

Ω

Q2

Cin2

Co21

Csoft1

0.01µF

Rfb11

17.8K

Rfb12

Co13

220µF

U1

FDS6912A

ISL6539

OCSET2

VSEN2

Rfb21

10K

Rfb22

10K

Cfb2

Csoft2

0.01µF

Rset2

100K

µ

0.01µF

4.7µF

4.7µH

Cb11

0.15µF

0.15µF

FIGURE 1. TYPICAL APPLICATION CIRCUIT AS DUAL SWITCHER, VOUT1 = 2.5V, VOUT2 = 1.8V

FIGURE 2. TYPICAL APPLICATION AS DDR MEMORY POWER SUPPLY, VOUT1 = 2.5V, VOUT2 = 1.25V

Rs1

2.0K

Rs2

1.0K

Q1

Lo1

4.6µF

Co11

Cin1

Cdc

4.7µF

D1

BAT54W

Rbt1

0

Ω

Cbt1

0.15µF

0.15µF

Rbt2

0

Ω

Q2

Co21

220µF

Co22

4.7µF

Rset1

100K

Csoft1

0.01µF

Rfb1

Rfb12

10K

Cfb1

0.01µF

SOFT1

PG1

OCSET1

EN1

GND

VSEN1

PGND1

LGATE1

ISEN1

PHASE1

UGATE1

BOOT1

VCC

VIN

OCSET2_VDDQ/2

PG2_REF

PGND2

LGATE2

ISEN2

PHASE2

UGATE2

BOOT2

VSEN2

GND

SOFT2

Vref (VDDQ/2)

Rd1

10K

VDDQ

VDDQ/2

Rd2

10K

Cf

0.1µF

VDDQ (2.5V)

VTT (1.25V)

Cref

DDR

Co13

220µF

EN2

VCC (5V)

Csoft2 (N/U)

U1

FDS6912A

FDS6912A

4.7µF

10µF

D2

BAT54W

Lo2

1.5µH

Cin2

4.7µF

17.8K

GND

Vin

VDDQ

Cref

4.7µF

0.01µF

ISL6539

Cbt2

ISL6539