General Description

Critical loads often employ parallel-connected power

supplies with redundancy to enhance system reliability.

The MAX8555/MAX8555A are highly integrated, inex-

pensive MOSFET controllers that provide isolation and

redundant power capability in high-reliability systems.

The MAX8555/MAX8555A are used in 0.5V to 3.3V sys-

tems, and have an internal charge pump to drive the

During startup, the MAX8555/MAX8555A monitor the

MOSFETs are turned on. The MAX8555/MAX8555A fea-

ture a dual-purpose TIMER input. A single external

resistor from TIMER to ground sets the turn-on speed of

the external MOSFETs. Optionally, the TIMER input can

be used as a logic enable input. Once the external

MOSFET is turned on, these controllers monitor the

load, protecting the bus against overvoltage, undervolt-

age, and reverse-current fault conditions. The

MAX8555 is available with a 40mV reverse-current

threshold, while the MAX8555A is available with a 20mV

reverse-current threshold.

Overvoltage and undervoltage fault thresholds are

adjustable and can be disabled. The current-limit trip

reducing component count. An open-drain, logic-low

fault output indicates if an overvoltage, undervoltage, or

reverse-current fault occurs. The MAX8555 and the

MAX8555A can shut down in response to a reverse-

current fault condition as quickly as 200ns.

Both devices come in space-saving 10-pin µMAX or

TDFN packages and are specified over the extended

-40°C to +85°C temperature range.

Applications

Point-of-Load Supplies

Power-Supply Modules

Servers

Telecom Power Supplies

Rectifiers

Redundant Power Supplies in High-Availability

Systems

Features

♦ Simple, Integrated, and Inexpensive MOSFET

Controllers

♦ ORing FET Drive for 0.5V to 3.3V

♦ Eliminate ORing Diode Power Dissipation

♦ Provide N+1 Redundant Supply Capability for

Highly Reliable Systems

♦ Isolate Failed Short-Circuit Supply from

Output BUS

♦ Respond to Reverse Short-Circuit Current

in 200ns

♦ Adjustable Blank Time

♦ Programmable Soft-Start

♦ Logic Enable Input

♦ Adjustable Overvoltage and Undervoltage

Trip Points

♦ Fault-Indicator Output

♦ Space-Saving Packages

Low-Cost, High-Reliability, 0.5V to 3.3V ORing

MOSFET Controllers

________________________________________________________________ Maxim Integrated Products

1

Ordering Information

13-3087; Rev 0; 1/04

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

EVALUATION

KIT

AVAILABLE

PART

TEMP

RANGE

PIN-

PACKAGE

TOP

MARK

MAX8555ETB

-40°C to 85°C

10 TDFN

3mm x 3mm*

ACC

MAX8555EUB

-40°C to 85°C

10 µMAX

8555EUB

MAX8555AETB

-40°C to 85°C

10 TDFN

3mm x 3mm*

ADD

MAX8555AEUB

-40°C to 85°C

10 µMAX

8555AEUB

1

2

3

4

5

10

9

8

7

6

CS+

CS-

OVP

VL

GND

GATE

MAX8555/

MAX8555A

µMAX

TOP VIEW

TIMER

UVP

FAULT

1

2

3

4

5

10

9

8

7

6

CS+

CS-

OVP

VL

GND

GATE

MAX8555/

MAX8555A

TDFN

TIMER

UVP

FAULT

Pin Configurations

*Exposed paddle

Typical Operating Circuit appears at end of data sheet.