February 2005

1

MIC2580A

MIC2580A

Micrel, Inc.

MIC2580A

Hot-Swap PCI Power Controller

General Description

The MIC2580A is a hot-swap controller that provides for safe

and orderly insertion and removal of PCI based adapter cards

from a PCI hot-plug compliant system backplane or

CompactPCI™ system.

The MIC2580A incorporates a circuit breaker function that

protects all four supplies (+12V, +5V, +3.3V, and –12V) upon

an overcurrent fault condition. Current foldback limiting pre-

vents large transient currents caused by plugging adapter

cards into live backplanes, such as in a CompactPCI system.

A programmable slew-rate control limits high inrush currents

to all loads that occur when power is applied to large capaci-

tive loads.

Voltage supervisory functions for all four power supplies are

provided by “power good” (/PWRGD) and “overcurrent fault”

(/FAULT) diagnostic outputs. Power good and overcurrent

fault include deglitch filters to prevent nuisance tripping.

Power good is active when all four supplies are within

tolerance. Fault (/FAULT) goes active upon overcurrent or

overtemperature conditions. The on-off control input (/ON) is

used to cycle power to the adapter card.

Typical Application

12VOUT

5VGATE

3VGATE

VPCHG

12VIN

/FAULT

GND

CSTART

/LPCIRST

5VIN

3VIN

/PCIRST

/EPWRGD

/ON

CSLEW

MIC2580A

5VSENSE

3VSENSE

5VOUT

3VOUT

/POR

CRST

IRF7413

IRF7413

+3.3V

+5V

+12V

/PWRGD

M12VIN

M12VOUT

+12V

+5V

+3.3V

GND

–12V

–12V

10mΩ

10mΩ

(PRECHARGE SUPPLY)

/HEALTHY

/BD_SEL

/PCI_RST

VIO

–12V/1A

GND

+3.3V/8A

+5V/8A

+12V/1A

/ENUM

/ON

/PCIRST

/PGD

Overcurrent

Fault

D0

D0

D1

D1

D2

D2

Dn

Dn

PCI

Controller

/LPCIRST

1.2k

1µF

1µF

1µF

1µF

CompactPCI™ Adapter with Early Power

Features

• PCI hot-plug and CompactPCI™ hot-swap support

• +12V, +5V, +3.3V, and –12V power supply control

•Circuit breaker function to protect system

•Programmable slew rate control for all supplies

• Foldback current-limiting

• +5V and +3.3V programmable current-limit thresholds

• Undervoltage and overcurrent diagnostic outputs

• Deglitch filters on diagnostic fault outputs

•Integrated +12V and –12V MOSFET switches

•Integrated high-side drivers for 3.3V and 5V external

switches

•Precharge supply for CompatPCI™ I/O termination

Applications

• PCI hot-plug systems

• CompactPCI™ hot-swap systems

Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

CompactPCI is a trademark of the PCI Industrial Computer Manufacturer’s Group.