LIA135

Overview

The LIA135 is a low voltage optically isolated error amplifier integrating a precision shunt reference, error amplifier, and optocoupler. It operates with an input voltage range of 1.6V to 10V over temperature. The device features a 1.299V reference voltage with ±1% accuracy from -40°C to +85°C. It provides a current transfer ratio (CTR) of 500% to 2000% and a common mode transient immunity of 5V/ns. The phototransistor output supports up to 50mA collector current and 25V collector-emitter voltage.

Feature Summary

• Integrates a precision programmable shunt reference, error amplifier, and optocoupler in a single package for simplified feedback loop design.
• Operates at low voltages starting from 1.6V, eliminating the need for auxiliary transformer windings in low-voltage power supply designs.
• Provides high current transfer ratio and industry-leading dynamic range by ensuring bias current does not pass through the LED.

Applications

• Low Voltage Power Supply Feedback
• Isolated Power Supply Feedback
• AC-to-DC Power Supplies
• DC-to-DC Converters

Procurement Notes

Verify the specific package variant required, as the LIA135 is available in 8-pin DIP tubes, surface mount tubes, and tape & reel formats. Confirm that the standard LIA135 meets the thermal requirements, noting that the LIA136 variant offers reduced dark current and higher common mode transient immunity for extended temperature ranges. Ensure handling procedures comply with MSL 1 ratings and ESD sensitivity standards during assembly.

Selection Notes

Select the LIA135 for applications requiring operation down to 1.6V input voltage where auxiliary biasing is unavailable. Choose this component when a combined error amplifier and optocoupler solution simplifies the feedback network. Consider the LIA136 if the application demands higher common mode transient immunity or operation at temperatures exceeding 85°C due to its optimized dark current characteristics.

Part Context

The LIA135 belongs to the LIA series of low voltage optically isolated error amplifiers manufactured by IXYS Integrated Circuits Division. It serves as a functional equivalent to a discrete precision shunt regulator paired with an optocoupler. The device is designed to replace multiple components in isolated power supply feedback loops, consolidating regulation and isolation functions into one compact integrated circuit.

Replacement Considerations

The LIA136 is the primary alternative within the same family, offering enhanced performance at elevated temperatures and improved common mode transient immunity. Designers should verify pin compatibility and thermal specifications when substituting between these variants.

FAQ

How is the minimum operating voltage achieved?

The device guarantees operation down to 1.6V input voltage across the specified temperature range, allowing direct biasing from the rectified secondary output without auxiliary windings.

What is the difference between LIA135 and LIA136 regarding the phototransistor base?

The LIA135 has no external base connection, whereas the LIA136 exposes the phototransistor base on Pin 2, allowing users to connect external components to reduce dark current and improve transient immunity.