SC4213H 查看數據表（PDF） - Semtech Corporation

零件编号

产品描述 (功能)

生产厂家

SC4213H

Very Low Input /Very Low Dropout 0.5 Amp Regulator With Enable

Semtech Corporation 

SC4213H

Applications Information (continued)

Introduction

The SC4213H is intended for applications where high

current capability and very low dropout voltage are

required. It provides a very simple, low cost solution that

uses very little PCB real estate. Additional features include

an enable pin to allow for a very low power consumption

standby mode, and a fully adjustable output.

Component Selection

Input capacitor: A large bulk capacitance ≥ 4.7µF (output

load) should be closely placed to the input supply pin of

the SC4213H to ensure that Vin does not sag below 1.4V.

Also a minimum of 4.7µF ceramic capacitor is recom-

mended to be placed directly next to the Vin pin. This

allows for the device being some distance from any bulk

capacitance on the rail. Additionally, input droop due to

load transients is reduced, improving load transient

response. Additional capacitance may be added if required

by the application.

Output capacitor: A minimum bulk capacitance of 4.7µF,

along with a 0.1µF ceramic decoupling capacitor is recom-

mended. Increasing the bulk capacitance will improve the

overall transient response. The use of multiple lower value

ceramic capacitors in parallel to achieve the desired bulk

capacitance will not cause stability issues. Although

designed for use with ceramic output capacitors, the

SC4213H is extremely tolerant of output capacitor ESR

values and thus will also work comfortably with tantalum

output capacitors.

≤50kΩ). A suitable value for R2 can be chosen in the range

of 1kΩ to 50kΩ. R1 can then be calculated from:

( ) R1 = R2 ⋅

VO − VREF

VREF

Enable: Pulling this pin below 0.4V turns the regulator off,

reducing the quiescent current to a fraction of its operat-

ing value. A pull up resistor up to 400kOhms should be

connected from this pin to the VIN pin in applications

where supply voltages of Vin < 1.9V are required. For

applications with higher voltages than 1.9V, the EN pin

can be left open or connected to VIN.

Thermal Considerations

The power dissipation in the SC4213H is given by:

( ) PD ≈ IO ⋅ VIN − VO

The allowable power dissipation will be dependant on the

thermal impedance achieved in the application. The derat-

ing curve below is valid for the thermal impedance speci-

fied in the Thermal Information section on page 3.

Power Derating Curve

1.5

1

RTH(JA)=105OC/W

Noise immunity: In very electrically noisy environments,

it is recommended that 0.1µF ceramic capacitors be placed

from VIN to GND and VO to GND as close to the device

pins as possible.

External voltage selection resistors: The use of 1%

resistors, and designing for a current flow ≥ 10µA is rec-

ommended to ensure a well regulated output (thus R2

0.5

0

0

25

50

75

100

125

Ambient Temperature T A (OC)

© 2010 Semtech Corporation



Share Link: