© Semiconductor Components Industries, LLC, 2004

January, 2004 − Rev. 5

1

Publication Order Number:

CS5231−3/D

CS5231−3

500 mA, 3.3 V Linear

Regulator with Auxiliary

Control

The CS5231−3 combines a three−terminal linear regulator with

circuitry controlling an external PFET transistor thus managing two

input supplies. The part provides a 3.3 V regulated output either from

the main 5.0 V supply or a 3.3 V auxiliary that switches on when the

5.0 V supply is not present. This delivers constant, uninterrupted

power to the load. The CS5231−3 meets Intel’s “Instantly Available”

power requirements which follows from the “Advanced Configuration

and Power Interface” (ACPI) standards developed by Intel, Microsoft

and Toshiba.

The CS5231−3 linear regulator provides a fixed 3.3 V output at

500 mA with an overall accuracy of

± 2.0%. The internal NPN−PNP

composite pass transistor provides a low dropout voltage and requires

less supply current than a straight PNP design. Full protection with

both current limit and thermal shutdown is provided.

Designed for low reverse current, the IC prevents excessive current

input voltage is lower than the output voltage.

The CS5231−3 can be used to provide power to an ASIC on a PCI

Network Interface Card (NIC). When the system enters a Sleep State

and the 5.0 V input drops below 4.4 V, the AuxDrv control signal on the

CS5231−3 is activated turning on the external PFET. This switches the

supply source from the 5.0 V input to the 3.3 V input through the PFET,

guaranteeing a constant 3.3 V output to the ASIC that is “glitch free.”

(TO263) package and the SOIC−8 4−Lead−fused (DF) package. Other

applications include desktop computers, power supplies with multiple

input sources and PCMCIA/PCI interface cards.

Features

± 2.0% Output Voltage

mA Reverse Output Current

PIN CONNECTIONS AND

MARKING DIAGRAMS

A

= Assembly Location

WL, L

= Wafer Lot

YY, Y

= Year

WW, W = Work Week

Device

Package

Shipping†

ORDERING INFORMATION

CS5231−3GDP5

50 Units/Rail

CS5231−3GDPR5

750 Tape & Reel

CS5231−3GDF8

SOIC−8

95 Units/Rail

CS5231−3GDFR8

SOIC−8

2500 Tape & Reel

SOIC−8

DF SUFFIX

CASE 751

Pin 1. No Connect

3. GND

5. AuxDrv

Tab = GND

DP SUFFIX

CASE 936AC

CS5231−3

AWLYWW

1

1

5

1

8

GND

GND

GND

GND

AuxDrv

NC

1

8

SOIC−8

http://onsemi.com

†For information on tape and reel specifications,

including part orientation and tape sizes, please

refer to our Tape and Reel Packaging Specifications

Brochure, BRD8011/D.