MAX5079

PRODUCTION

ORing MOSFET Controller with Ultra-Fast 200ns Turn-Off

Data Sheet (Rev. 4) Product Selection Table

Part Models: 2
1ku List Price: Starting From $3.40

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Overview

Drives External MOSFETs Reducing Power Dissipation and Board Space
- 2.75V to 13.2V Input ORing Voltage
- 1V to 13.2V Input ORing Voltage with 2.75V AuxiliaryVoltage
- 14-Pin TSSOP Package
Protection Features Increase System Reliability
- 2A MOSFET Gate Pulldown Current During Fault Condition
- Ultra-Fast 200ns, MOSFET Turn-Off During Fault Condition
- Supply Undervoltage and Bus Overvoltage Detection
- Power-Good (PGOOD) and Overvoltage (OVP) Outputs for Fault Detection

The MAX5079 ORing MOSFET controller replaces ORing diodes in high-reliability redundant, parallel-connected power supplies. Despite their low forward-voltage drop, ORing Schottky diodes cause excessive power dissipation at high currents. The MAX5079 allows for the use of low-on-resistance n-channel power MOSFETs to replace the Schottky diodes. This results in low power dissipation, smaller size, and elimination of heatsinks in high-power applications.

The MAX5079 operates from 2.75V to 13.2V and includes a charge pump to drive the high-side n-channel MOSFET. Operation down to 1V is possible if an auxiliary voltage of at least 2.75V is available. When the controller detects a positive voltage difference between IN and BUS, the n-channel MOSFET is turned on. The MOSFET is turned off as soon as the MAX5079 sees a negative potential at IN with respect to the BUS voltage, and is automatically turned back on when the positive potential is restored. Under fault conditions, the ORing MOSFET's gate is pulled down with a 1A current, providing an ultra-fast 200ns turn-off. The reverse voltage turn-off threshold is externally adjustable to avoid unintentional turn-off of the ORing MOSFET due to glitches at IN or BUS caused by hot plugging the power supply.

Additional features include an OVP flag to facilitate shutdown of a failed power supply due to an overvoltage condition, and a PGOOD signal that indicates if V_IN is either below the undervoltage lockout or V_BUS is in an overvoltage condition. The MAX5079 operates over the -40°C to +85°C temperature range and is available in a space-saving 14-pin TSSOP package.

Applications

Base-Station Line Cards
N+1 Redundant Power Systems
Networking Line Cards
Paralleled DC-DC Converter Modules
RAID
Servers

Part Models: 2
1ku List Price: Starting From $3.40

Documentation

Data Sheet 1

MAX5079: ORing MOSFET Controller with Ultra-Fast 200ns Turn-Off Data Sheet (Rev.4) 07/22/2019

Reliability Data 1

MAX5079 Reliability Data 01/12/2023

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 Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
MAX5079EUD+	Thin Shrink Small-Outline Package	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
MAX5079EUD+T	Thin Shrink Small-Outline Package	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys

This is the most up-to-date revision of the Data Sheet.

Software Resources

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Evaluation Kits

Evaluation Kit for the MAX5079

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Features and Benefits

N+1 Redundant System for a 3V to 13.2V Bus (1V Circuit Operation with Reconfiguration)
Eliminates ORing Diode Power Dissipation
Adjustable Reverse-Voltage-Detection Threshold
Adjustable Undervoltage Threshold (Configured to 3.0V)
Adjustable Overvoltage Threshold (Configured to 13.2V)
OVP_ and PGOOD_ Status Indicators
Supports Up to 20A of Load Current
Simulates Catastrophic Fault Conditions at the Inputs
Fully Assembled and Tested

Product Details

The MAX5079 evaluation kit (EV kit) demonstrates the functionality of the MAX5079 ORing MOSFET controller in a parallel-connected power-supply system. The EV kit circuit is configured to connect two power supplies in parallel using ORing MOSFETs to simulate a fault condition, and to depict the isolation of the bus during the fault condition. The EV kit is configured for 3.0V to 12.6V input operation. The external undervoltage-lockout threshold is configured to 3.0V, and the overvoltage threshold is configured to 13.2V. Operation down to 1V is possible with circuit reconfiguration and an additional auxiliary power supply. The MAX5079 controller, along with an n-channel MOSFET, provides the functionality of a diode with an extremely low forward-voltage drop.

The MAX5079 controllers on the EV kit monitor the respective input voltages at VIN1 and VIN2 with respect to the power bus voltage V_BUS. When the V_{IN_} voltage rises above the V_BUS voltage, the MOSFET is quickly turned on. If either V_{IN_} power-supply voltage falls below V_BUS, the MAX5079 discharges the MOSFET gate with 2A (typ) sink current and turns off the MOSFET within 200ns (typ), effectively isolating the bus.