MAX8585

PRODUCTION

ORing MOSFET Controllers with Fastest Fault Isolation for Redundant Power Supplies

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

Data Sheet (Rev. 1) Product Selection Table
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Overview

  • 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

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 VCC + 10V. The MAX8536 is used in 3.3V and 5V systems, with a chargepump output of VCC + 5V.

During startup, the MAX8535/MAX8536/MAX8585 monitor the voltage drop across external MOSFETs. Once VCC 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' RDS(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
MAX8585
ORing MOSFET Controllers with Fastest Fault Isolation for Redundant Power Supplies
MAX8535, MAX8536, MAX8585: Typical Operating Circuit
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Documentation

Data Sheet 1

Reliability Data 1

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Evaluation Kits

MAX8536EVKIT

Evaluation Kit for the MAX8536

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Features and 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

Product Details

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

MAX8535EVKIT

Evaluation Kit for the MAX8535

Buy Now View Details

Features and 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

Product Details

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
MAX8536EVKIT
Evaluation Kit for the MAX8536
MAX8535EVKIT
Evaluation Kit for the MAX8535

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