© Semiconductor Components Industries, LLC, 2006

September, 2006 − Rev. 3

1

Publication Order Number:

MC33566/D

MC33566

Smart Voltage Regulator for

Peripheral Card Applications

The MC33566 Low Dropout Regulator is designed for computer

peripheral card applications complying with the instantly available

requirements as specified by ACPI objectives. The MC33566 permits

glitch−free transitions from “sleep” to “active” system modes and has

internal logic circuitry to detect whether the system is being powered

from the motherboard main 5.0 V power supply or the 3.3 V aux supply.

The MC33566 provides a regulated output voltage of 3.3 V via

either an internal low dropout 5.0 V−to−3.3 V voltage regulator or an

external P−channel MOSFET, depending on the operating status of the

system in which the card is installed. During normal operating mode

(5.0 V main supply available) the 3.3 V output is provided from the

internal low dropout regulator at an output current of 0.4 A. When the

motherboard enters sleep mode, the MC33566 operates from the 3.3 V

aux supply and routes the aux current to the output via the external

P−channel MOSFET bypass transistor controlled by the drive out pin.

As a result, the output voltage provided to the peripheral card remains

constant at 3.3 V even during host systems transitions to and from

sleep mode.

MC33566 Features:

Figure 1. Simplified Block Diagram

Compensation

&

Hysteresis

Ref &

Detect

5V detect

Comp

Driver

Drive out

Hyst sw

External

P−channel

MOSFET

External

4.7

μF

cap

LDO

D2T SUFFIX

CASE 936A

5

1

Device

Package

ORDERING INFORMATION

MC33566D2T−1

50 Units/Rail

M5

661

AWLYWW

15

MARKING

DIAGRAM

A

= Assembly Location

WL = Wafer Lot

Y

= Year

WW = Work Week

Pin

1. Vaux

3. Gnd

5. Drv

Note: Tab is ground

MC33566D2T−1RK

800 Tape & Reel

http://onsemi.com

†For information on tape and reel specifications,

including part orientation and tape sizes, please

refer to our Tape and Reel Packaging Specification

Brochure, BRD8011/D.