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SC4603

Very Low Input, MHz Operation,

High Efficiency Synchronous Buck

POWER MANAGEMENT

Revision: May 16, 2008

Description

Features

Applications

Typical Application Circuit

BICMOS voltage mode PWM controller

2.25V to 5.5V Input voltage range

Output voltages as low as 0.5V

Sleep mode (Icc = 10µA typ)

Lossless adjustable overcurrent protection

Combination pulse by pulse & hiccup mode current

limit

High efficiency synchronous switching

0% to 100% Duty cycle range

Synchronization to external clock

Asynchronous start-up

1MHz frequency of operation

10-Pin MSOP surface mount package. Lead free

product. This product is fully WEEE and RoHS

compliant

Distributed power architecture

Servers/workstations

Local microprocessor core power supplies

DSP and I/O power supplies

Battery powered applications

Telecommunication equipment

Data processing applications

The SC4603 is a voltage mode step down (buck) regula-

tor controller that provides accurate high efficiency power

conversion from input supply range 2.25V 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 SC4603 drives external complementary power

MOSFETs; P-channel on the high side and N-channel on

the low side. The use of high side P-channel MOSFETs

eliminates the need for an external charge pump and

simplifies the high side gate driver. Non-overlap protec-

tion is provided for the gate drive signals to prevent shoot

through of the MOSFET pair. The voltage drop across the

P-channel MOSFET during its conduction is sensed for

lossless short circuit current limiting.

A low power sleep mode can be achieved by forcing the

SYNC/SLEEP pin below 0.8V. A synchronous mode of op-

eration is activated as the SYNC/SLEEP pin is driven by

an external clock. The quiescent supply current in sleep

internally provided to prevent output voltage overshoot

during start-up. A 100% maximum duty cycle allows the

SC4603 to operate as a low dropout regulator in the

event of a low battery condition.

The SC4603 is an ideal choice for 3.3V, 5V or other low

input supply systems. It’s available in 10 pin MSOP

package.

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

VCC

1

SYNC

2

COMP

3

VSENSE

4

FS

5

ISET

6

PHASE

7

GND

8

NDRV

9

PDRV

10

U1

SC4603

R15

1

C3

4.7u

C7

150u

C14

33n

R6

1.0

R5

1.0

R9

6.98k

Vout = 1.5V (as low as 0.5V * ) /6A

M2

C10

22u

C11

22u

C12

22u

Vin = 2.25V ~ 5.5V

C13

22u

C4

22u

RT 34.8k

C1

150p

C2

1n

R1

20k

R3

L1

2.3u

C9

1.2n

R8

806

M1

R7

14k

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

VCC

1

SYNC

2

COMP

3

VSENSE

4

FS

5

ISET

6

PHASE

7

GND

8

NDRV

9

PDRV

10

U1

SC4603

R15

1

C3

4.7u

C7

150u

C14

33n

R6

1.0

R5

1.0

R9

6.98k

Vout = 1.5V (as low as 0.5V * ) /6A

M2

C10

22u

C11

22u

C12

22u

Vin = 2.25V ~ 5.5V

C13

22u

C4

22u

RT 34.8k

C1

150p

C2

1n

R1

20k

R3

L1

2.3u

C9

1.2n

R8

806

M1

R7

14k