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SC4609

Low Input, MHz Operation,

High Efficiency Synchronous Buck

POWER MANAGEMENT

Revision: February 8, 2006

Description

Features

Applications

Typical Application Circuit

Asynchronous start up

Programmable switching frequency up to 1MHz

BiCMOS voltage mode PWM controller

2.7V to 5.5V input voltage range

Output voltage as low as 0.5V

+/-1% reference accuracy

Sleep mode (Icc = 10µA typ)

Adjustable lossless short circuit current limiting

Combination pulse by pulse & hiccup mode

current limit

High efficiency synchronous switching

1A peak current driver

External soft start

12-pin MLP Lead-free package, fully WEEE and RoHS

compliant

Distributed power architecture

Servers/workstations

Local microprocessor core power supplies

DSP and I/O power supplies

Battery-powered applications

Telecommunications equipment

Data processing applications

The SC4609 is a voltage mode step down (buck) regula-

tor controller that provides accurate high efficiency power

conversion from an input supply range of 2.7V to 5.5V. A

high level of integration reduces external component

count, and makes it suitable for low voltage applications

where cost, size and efficiency are critical. The SC4609

is capable of producing an output voltage as low as 0.5V.

The SC4609 drives external, N-channel MOSFETs with a

peak gate current of 1A. A non-overlap protection is pro-

vided for the gate drive signals to prevent shoot through

of the MOSFET pair. The SC4609 features lossless cur-

rent sensing of the voltage drop across the drain to

source resistance of the high side MOSFET during its

conduction period. Its switching frequency can be pro-

grammed up to 1MHz.

The quiescent supply current in sleep mode is typically

vent output voltage overshoot during start-up.

The SC4609 is an ideal choice for converting 3.3V, 5V or

other low input supply voltages. It’s available in 12 pin

MLP package.

R3

C3

4.7u

C2 2.2n

R1

14.3k

C1

180p

D2

L1

1.8u

C5

22u

C4

22u

Vout=1.5V (as low as 0.5V*) / 12A

C17

1u

M11

C10

220u

M2

C9

4.7n

R8

200

R7

10k

R9

4.99k

Vin=2.7V - 5.5V

R6

1

R5

1

C16

560pF

VCC

1

ISET

2

COMP

3

FSET

4

BST

12

DRVH

11

DRVL

9

AGND

7

PGND

8

PHASE

10

SS

6

VSENSE

5

U1

SC4609

C6

330u

C13

22u

C14

22u

R13

1

Css

22u

*External components can be modified to provide a Vout as low as 0.5V

R3

C3

4.7u

C2 2.2n

R1

14.3k

C1

180p

D2

L1

1.8u

C5

22u

C4

22u

Vout=1.5V (as low as 0.5V*) / 12A

C17

1u

M11

C10

220u

M2

C9

4.7n

R8

200

R7

10k

R9

4.99k

Vin=2.7V - 5.5V

R6

1

R5

1

C16

560pF

VCC

1

ISET

2

COMP

3

FSET

4

BST

12

DRVH

11

DRVL

9

AGND

7

PGND

8

PHASE

10

SS

6

VSENSE

5

U1

SC4609

C6

330u

C13

22u

C14

22u

R13

1

Css

22u

*External components can be modified to provide a Vout as low as 0.5V