FTTH fiber-to-the-home solutions
Optical communication component solutions

Optocoupler current conversion ratio

The current in each half of the circuit is linked by the Current Transfer Ratio or CTR, which is simply the ratio of output current to the input current (I C /I F) usually expressed as a percentage. E...

Jan 08, 2026

ANO007 | Understanding Phototransistor Optocouplers

The ratio between the phototransistor collector current (IC) and the IR-LED current (IF) represents the main optocoupler parameter: the current-transfer-ratio (CTR).

Mar 28, 2026

Make sure your optocoupler is properly biased

The current transfer ratio (CTR) is the current gain from the LED to the photo detector, and typically has a very wide tolerance. When you are designing an isolated feedback network, you must consider the

Apr 07, 2026

Guidelines for reading an optocoupler datasheet

Special specifications such as high operating temperature, high current transfer ratio, and low coupling capacitance are identified to give an overview. The application section introduces the most common

Nov 21, 2025

Optocoupler (Optical Isolator) Current Transfer Ratio and Isolation

2. Isolation Voltage and Insulation Performance Data: At 25℃, the ultimate AC breakdown voltage of all four optocoupler types exceeded 7kVrms, with a 1-minute withstand voltage of 5kVrms showing

Feb 09, 2026

Transistor Output Optocouplers Frequently Asked Questions (FAQs)

CTR is the abbreviation for Current Transfer Ratio. It describes the two main parameters of optocouplers and is obtained by dividing the output current of the transistor by the forward current of the emitting

Oct 10, 2025

Optocoupler Circuit Design and Detailed Analysis

Once you know what a CTR is and learn how to use it, then Optocoupler circuit design is that easy. Current transfer ratio or just CTR is the ratio of the collector to the forward current which is expressed

Feb 06, 2026

opto isolator

As I understand the optocoupler current transfer ratio, CTR is like the hfe of a transistor. I can''t understand if the CTR is or isn''t a critical value and for

Apr 22, 2026

Opto Coupler CTR Explanation

Opto coupler CTR explanation is not well elaborated by other authors and before I was also having hard time of understanding what is it. Current transfer ratio or

Sep 19, 2025

opto isolator

Current Transfer Ratio (CTR) can be critical in certain applications, such as providing the feedback value of a variable across an isolation barrier,

Jan 04, 2026

What is Current Transfer Ratio (CTR)?

What is Current Transfer Ratio (CTR)? Current Transfer Ratio (CTR) is a ratio of the output collector current to the input forward current and is represented in a

Oct 18, 2025

{1403} Optocoupler Function & CTR Explained | Current Transfer Ratio

In this video number {1403} Optocoupler Function & CTR Explained | Current Transfer Ratio Calculation in Detail. In this detailed tutorial, Muhammad Ashraf from Haseeb Electronics explains the

Apr 11, 2026

What is Current Transfer Ratio (CTR) and why does it matter?

The gain of an optocoupler is expressed as the Current Transfer Ratio (CTR). It is defined as the ratio of the phototransistor output current (Ic) to the LED input current (If), expressed as a

May 19, 2026

Factors Affecting Current Transfer Ratio of Optocoupler

In circuit involving optocoupler, in some cases design engineers failed to fully consider the factors affecting current transfer ratio. As a result, design issue

Nov 21, 2025

Understanding the CTR of an optocoupler

I''m having a particularly hard time understanding the CTR (Current Transfer Ratio), and how that will impact my choice. I''ve read several things that

Sep 09, 2025

The Ultimate Optocouplers Guide: Isolation, Types, and

Alt Text: Internal diagram of an optocoupler illustrating the LED, photosensor, and the principle of galvanic isolation.] 1.2 Understanding Current

May 08, 2026

Using Opto Couplers

Current Transfer Ratio The current in each half of the circuit is linked by the Current Transfer Ratio or CTR, which is simply the ratio of output current to the input

Apr 22, 2026

Phototransistor Optocoupler Insights | PDF | Bipolar

This application note explains the operation and design considerations of phototransistor optocouplers, specifically Würth Elektronik''s WL-OCPT series. It

Nov 07, 2025

Guidelines for reading an optocoupler datasheet

CTR is very much like a gain value for transistors. The CTR describes the ratio between the input current of the infrared diode (I F) and the maximum possible current on the output transistor through

Jul 27, 2025

Phototransistor Optocouplers: Understanding & Design

The optocoupler''s current-transfer-ratio (CTR) and output parasitic capacitance which limit its operating frequency range and switching performance are

Dec 05, 2025

How to Use Optocoupler Normalized Curves

The gain of the optocoupler is expressed as a current transfer ratio (CTR), which is the collector current (IC) of the output divided by the forward current (IF) of the input and multiplied by 100 %.

Dec 21, 2025

Optocoupler Circuit Design and Detailed Analysis

Actually, Optocoupler circuit design is not that difficult as some thought. It''s just like you are designing a BJT circuit. If a BJT has its beta or current gain, optocoupler

Sep 03, 2025

Transistor Optocoupler CTR (Current Transfer Ratio) Calculator

Calculate the Current Transfer Ratio (CTR) of a transistor optocoupler using this calculator and understand the CTR formula.

Aug 21, 2025

Current Transfer Ratio Calculator

The Current Transfer Ratio Calculator determine the efficiency of current transfer between the input and output of an optocoupler circuit.

Sep 04, 2025

5-10. Characteristics of Photocouplers (Current Transfer

Current transfer ratio of transistor coupler: It is expressed by the amplification ratio of the output current with respect to the input current like the transistor h FE.

May 02, 2026

Optocoupler Device CTR and Circuit CTR Explained

The ratio of the collector current to the forward current computed at saturation is the one called as the circuit CTR. To summarize everything, optocoupler device CTR

Jan 01, 2026

Opto-isolators – solid-state relay, isolation voltage,

Opto-isolators, or optocouplers, transmit electrical signals between circuits while providing electrical isolation.

Feb 04, 2026

What is the current transfer ratio?

The current transfer ratio (CTR) refers to the ratio of the collector current at the output side IC to the input current passed to the LED at the input side IF

Jul 30, 2025

Current Transfer Ratio (CTR) and Response Time of Photocouplers

Learn about the current transfer ratio (CTR) characteristics and response time of photocouplers/optocouplers.

More industry information

Contact Us

We Look Forward to Working with You

Contact Information

Phone +27 64 827 3915
Address Unit 9, Highveld Technopark, 43 Atlas Road, Johannesburg, 2196, South Africa

Send an Inquiry