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SC4601

Low Input, High Efficiency

Synchronous, Step Down Controller

POWER MANAGEMENT

Revision: February 22, 2006

Description

Features

Applications

Typical Application Circuit

Programmable switching frequency up to 600KHz

BICMOS voltage mode PWM controller

2.75V to 5.5V Input voltage range

Output voltage as low as 0.8V

+/-1% Reference accuracy

Sleep mode (Icc = 10µA typ)

Lossless adjustable overcurrent protection

Combination pulse by pulse & hiccup mode

current limit

High efficiency synchronous switching

Up to 100% Duty cycle range

Synchronization to external clock

10-Pin MSOP surface mount package. Available in

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

Telecommunication equipment

Data processing applications

The SC4601 is a voltage mode step down (buck) regula-

tor controller that provides accurate high efficiency power

conversion from input supply range 2.75V 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 SC4601 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

SC4601 to operate as a low dropout regulator in the

event of a low battery condition. Its switching frequency

can be programmed up to 600KHz.

The SC4601 is an ideal choice for 3.3V, 5V or other low

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

package.

VCC

1

SYNC

2

COMP

3

VSENSE

4

FS

5

ISET

6

PHASE

7

GND

8

NDRV

9

PDRV

10

U1

SC4601

R15

1

C3

4.7u

C7

150u

C14

33n

R6

1.0

R5

1.0

R9

5.11k

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

M2

C10

22u

C11

22u

C12

22u

Vin = 2.75V ~ 5.5V

C13

22u

C4

22u

RT

30.1K

C1

470p

C2

6.8n

R1

5.11K

R3

L1

1.6u

C9

3.9n

R8

147

M1

R7

4.53k

* External components can be modified to provide a V