Analog Devices LT8440

Description

The LT8440 is a power conditioner for intrinsically safe, industrial ethernet ports in hazardous or explosive environments. The internal pass transistor is normally fully enhanced to deliver power to the load efficiently. In case of load circuit failures, the FET is modulated to limit the power to less than 650mW if line voltage ≤ 18.5V or less than 35mA if line voltage > 18.5V. The internal shunt transistor draws current parallel with the load up to the 500mW minimum guaranteed for Class A load power ports in compliance with Advanced Physical Layer (APL) standard or to 20mA minimum guaranteed if line voltage > 18.5V. The line voltage is sensed with two input pins that are insensitive to polarity, which can be connected in front of the port rectifier and incorporate the rectifier power consumption in the limitation of total power. The line current is measured as a voltage across the internal sense resistor, and the shunt current and the current limit are automatically adjusted for line voltage.

Features

650mW Power Limit for Intrinsic Safety Thermal

• Rating when Line Voltage ≤ 18.5V

• 35mA Current Limit if Line Voltage > 18.5V

• 55mA Current Limit for APL Class A Devices

• Shunt Regulator for Mitigating Load Changes

• Guaranteed 20mA Rectifier Current for Signal Integrity

• Guaranteed to deliver full 500mW APL power to the load

• 6V to 36V Input Voltage

• Integrated Current Sense Resistor

• Polarity Insensitive Line Voltage Detection

• 8-Lead SOIC Package with Exposed Pad

Typical applications

More information

• Datasheet
• IC product information