MAX8535

ORing MOSFET Controllers with Fastest Fault Isolation for Redundant Power Supplies

Simplest, smallest OR-ing MOSFET Controllers with Fastest Reverse-Current Protection

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Overview

Features and Benefits
Product Details

Features and Benefits

Simple, Integrated, and Inexpensive ORing MOSFET Controller
ORing MOSFET Drive for 12V (MAX8535/MAX8585) and 3.3V or 5V (MAX8536) Bus
Eliminates ORing Diode Power Dissipation and Reverse Leakage Current
Provides N + 1 Redundant Supply Capability for Highly Reliable Systems
Isolates Failed Supply from Output Bus in <1µs
Reverse-Current Flow Detection
Programmable Soft-Start
Logic-Enable Input
Adjustable Overvoltage and Undervoltage Trip Points
Fault-Indicator Output
Space-Saving 8-Pin µMAX Package

Product Details

Critical loads often employ parallel-connected power supplies with redundancy in order to enhance system reliability. The MAX8535/MAX8536/MAX8585 are highly integrated but inexpensive MOSFET controllers that provide isolation and redundant power capability in high-reliability systems. The MAX8535/MAX8585 are used in 12V systems, and have an internal charge pump to drive the gates of the n-channel pass elements to V_CC + 10V. The MAX8536 is used in 3.3V and 5V systems, with a chargepump output of V_CC + 5V.

During startup, the MAX8535/MAX8536/MAX8585 monitor the voltage drop across external MOSFETs. Once V_CC approaches or exceeds the bus voltage, the MOSFETs are turned on. The MAX8535/MAX8536/MAX8585 feature 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 pin. Once the device is turned on, the MAX8535/MAX8536/MAX8585 monitor the load, protecting against overvoltage, undervoltage, and reverse-current conditions.

Overvoltage and undervoltage fault thresholds are adjustable and can be disabled. The current-limit trip points are set by the external MOSFETs' R_DS(ON), reducing component count. An open-drain logic-low fault output indicates if an overvoltage, undervoltage, or reverse-current fault occurs.

All devices come in a space-saving 8-pin µMAX® package and are specified over the extended -40°C to +85°C temperature range.

Applications

Network/Telecom Power Supplies
On-Board Redundant Power Supplies in Blade Servers
Rectifiers
Redundant Power Supplies in High-Availability Systems
Silver Box Supplies for Servers

Product Categories

Power Monitor, Control, and Protection
- PowerPath, Ideal Diodes, and Load Switches

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Product Lifecycle Production

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.

Evaluation Kits (2)

MAX8535EVKIT

Evaluation Kit for the MAX8535

MAX8536EVKIT

Evaluation Kit for the MAX8536

MAX8535EVKIT

View Detailed Evaluation Kit Information

The MAX8535 evaluation (EV) kit circuit demonstrates the functionality of the MAX8535 ORing MOSFET controller that provides redundancy and fault isolation to highly reliable power systems. The MAX8535 EV kit board operates in 12V systems.

During startup, the EV kit monitors the voltage difference between a power supply and a power bus. Once the voltage difference is less than 0.4V, the MAX8535 turns on two ORing MOSFETs, linking the power supply and power bus. Once the MOSFETs are on, the EV kit monitors the load current and voltages to protect against undervoltage (UVP), overvoltage (OVP), and reverse-current fault conditions.

The OVP and UVP thresholds are adjustable and can be disabled. The UVP threshold is set to 8V and the OVP threshold is set to 13.75V. An active-low FAULT signal output is provided for circuit monitoring.

Applications

Network/Telecom Power Supplies
On-Board Redundant Power Supplies in Blade Servers
Rectifiers
Redundant Power Supplies in High-Availability Systems
Silver Box Supplies for Servers

Features & Benefits

Fault Power-Supply Isolation for 12V Bus
Eliminates ORing Diode Power Dissipation
Reverse-Current Detection
Adjustable Undervoltage Threshold (Configured to 8V)
Adjustable Overvoltage Threshold (Configured to 13.7V)
Active-Low FAULT Output Status Indicator
Adjustable Soft-Start
Up to 20A of Load Current
Surface-Mount Construction
Fully Assembled and Tested

MAX8536EVKIT

View Detailed Evaluation Kit Information

The MAX8536 evaluation (EV) kit circuit demonstrates the functionality of the MAX8536 ORing MOSFET controller that provides redundancy and fault isolation to highly reliable power systems. The EV kit board can operate in 5V and 3.3V systems. The EV kit is configured for 5V operation.

During startup, the EV kit monitors the voltage difference between a power supply and a power bus. Once the voltage difference is less than 0.4V (typ), the IC turns on two ORing MOSFETs, linking the power supply and power bus. Once the MOSFETs are on, the EV kit monitors the load current and voltages to protect against undervoltage (UVP), overvoltage (OVP), and reverse-current fault conditions.

The OVP and UVP thresholds are adjustable and can be disabled. The UVP threshold is set to 2.9V, and the OVP threshold is set to 5.75V. An active-low FAULT signal output is provided for circuit monitoring.

Applications

Network/Telecom Power Supplies
On-Board Redundant Power Supplies in Blade Servers
Rectifiers
Redundant Power Supplies in High-Availability Systems
Silver Box Supplies for Servers

Features & Benefits

Fault Power-Supply Isolation for 5V and 3.3V Bus
Eliminates ORing Diode Power Dissipation
Reverse-Current Detection
Adjustable Undervoltage Threshold (Configured to 2.9V)
Adjustable Overvoltage Threshold (Configured to 5.75V)
Active-Low FAULT Output Status Indicator
Adjustable Soft-Start
Up to 20A of Load Current
Surface-Mount Construction
Proven PCB Layout
Fully Assembled and Tested

Documentation & Resources

Data Sheets

MAX8535-MAX8585: ORing MOSFET Controllers with Fastest Fault Isolation for Redundant Power Supplies Data Sheet (Rev. 1)
5/3/2004
PDF

Design Resources

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.View our quality and reliability program and certifications for more information.

Part Number	Material Declaration	Reliability Data	Pin/Package Drawing	CAD Symbols, Footprints & 3D Models
MAX8535EUA+	Material Declaration	Reliability Data	Micro-MAX, Thin Shrink Small-Outline	Ultra Librarian SamacSys
MAX8535EUA+T	Material Declaration	Reliability Data	Micro-MAX, Thin Shrink Small-Outline	Ultra Librarian SamacSys
Wafer Fabrication Data

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(*)The 1Ku list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.

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