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

Product Details

Key Features

Simplified Block Diagram

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Key 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

Applications/Uses

  • Point-of-Load Supplies
  • Power-Supply Modules
  • Rectifiers
  • Redundant Power Supplies in High-Availability Systems
  • Servers
  • Telecom Power Supplies

Description

Critical loads often employ parallel-connected power supplies with redundancy to enhance system reliability. The MAX8555/MAX8555A are highly integrated, inexpensive MOSFET controllers that provide isolation and redundant power capability in high-reliability systems. The MAX8555/MAX8555A are used in 0.5V to 3.3V systems, and have an internal charge pump to drive the gates of the N-channel pass elements to (VCS+ + 5V).

During startup, the MAX8555/MAX8555A monitor the voltage drop across the external MOSFETs. Once VCS+ approaches or exceeds the bus voltage (VCS-), the MOSFETs are turned on. The MAX8555/MAX8555A 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 input. Once the external MOSFET is turned on, these controllers monitor the load, protecting the bus against overvoltage, undervoltage, 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 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. 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.

Simplified Block Diagram

MAX8555, MAX8555A: Typical Operating Circuit MAX8555, MAX8555A: Typical Operating Circuit Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .

Sampling:
Selecting the Sample button above will redirect to the third-party ADI Sample Site. The part selected will carry over to your cart on this site once logged in. Please create a new account there if you have never used the site before. Contact SampleSupport@analog.com with any questions regarding this Sample Site.