SC4501 데이터 시트보기 (PDF) - Semtech Corporation

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SC4501

2Amp, 2MHz Step-Up Switching Regulator with Soft-Start

Semtech Corporation 

SC4501

POWER MANAGEMENT

PBilnocDkeDsciarigprtaiomns (MSOP-8)

Pin

Pin Name Pin Function

1

COMP The output of the internal transconductance error amplifier. This pin is used for loop compensation.

2

FB

The inverting input of the error amplifier. Tie to an external resistive divider to set the output voltage.

Shutdown Pin. The accurate 1.1V shutdown threshold and the 4.6uA shutdown pin current

hysteresis allow the user to set the undervoltage lockout threshold and hysteresis for the switching

3

SHDN

regulator. Pulling this pin below 0.1V causes the converter to shut down to low quiescent current.

Tie this pin to IN if the UVLO and the shutdown features are not used. This pin should not be left

floating.

4

GND

Ground. Tie to the ground plane.

5

SW

Collector of the internal power transistor. Connect to the boost inductor and the rectifying diode.

6

IN

Power Supply Pin. Bypassed with capacitors close to the pin.

7

ROSC

A resistor from this pin to the ground sets the switching frequency.

8

SS

Soft-Start Pin. A capacitor from this pin to the ground lengthens the start-up time and reduces start-

up current.

Exposed Pad The exposed pad must be soldered to the ground plane on the PCB for good thermal conduction.

Block Diagram

IN

6

SW

5

4.6µA

SHDN

3

1.1V

+

CMP

-

VOLTAGE

REFERENCE

THERMAL

SHUTDOW N

INTERNAL

SUPPL Y

ENABLE

CLK

REG

FB

2

COMP

1

SS

8

1.242V

REG_GOOD

ENABL E

+

EA

-

ROS C

7

REG

1.5µA

CLK

-

PWM

+

R

Q

S

+

ILIM

-

I-LIMIT

+

Σ

+

OSCILLATOR

SLOP E COMP

+

ISEN

-

RSENSE

4

GND

© 2005 Semtech Corp.

Figure 2. SC4501 (MSOP-8) Block Diagram.

4

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