Identify the load
A feedback loop, a logic input and an external power triac place different demands on the output stage. Record the circuit’s required function first.
Optoelectronics · Component selection
Optocouplers
Which output does your circuit need?
Compare photocouplers by output type, channel count, package and isolation test voltage. Find a complete ordering code, open its datasheet and add the required quantity to your RFQ.
Inside a phototransistor optocouplerFIG. 01
Choose by requirement
Four details that narrow your shortlist
Start with the receiving circuit and the LED current your input can supply. Keep the ordering suffix with the specifications when comparing parts.
Find the drive budget
Record the available LED forward current and temperature range. For a transistor output, check the minimum CTR at a comparable test point.
Specify the barrier
List the working voltage, transient requirements and insulation class your design requires. Keep the withstand-test duration and units with its voltage.
Match the board
Count channels and pins separately. Confirm mounting style, lead span and orientation against the land pattern or through-hole drawing.
Product catalog
Find an optocoupler by part number or specification
Search for an exact MPN, manufacturer or SKU. Select a row to check its datasheet or add the part to your inquiry.
Filters use explicit listing values. Open the datasheet for test duration, working voltage and insulation conditions.
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| Part number / manufacturer | Output type | Channels | Package | Isolation test voltage | Details / RFQ |
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Output types
Which output fits the receiving circuit?
The LED input describes how the signal crosses the barrier. The receiver determines which specification to compare.
Phototransistor output
The receiver provides collector current as a function of LED drive. This is useful for isolated feedback or a pulled-up sensing input.
- Match the CTR bin at the intended LED current.
- Check the output voltage, load and saturation voltage.
- Check switching times with the specified load.
Logic-output photocoupler
An optical receiver with a logic output has threshold and timing specifications. A totem-pole output and an open-collector output have different interface requirements.
- Check output polarity, supply and any pull-up.
- Compare maximum threshold LED current.
- Compare both propagation delays under the stated load.
Phototriac output
A triac driver optocoupler can trigger an external power triac. A zero-cross type delays turn-on until the AC voltage falls within its trigger window.
- Choose zero-cross or random-phase operation.
- Check trigger LED current and off-state voltage.
- Verify the external triac’s gate-drive circuit.
Other optocoupler outputs
- Photodarlington
- Compare minimum CTR at the specified LED drive and examine turn-off time with your load. Vishay IL221AT series ↗
- Linear photodiode
- A feedback photodiode and an output photodiode can form an isolated analog link. Match the transfer-gain bin and external amplifier circuit. Vishay IL300 ↗
- Gate driver
- Compare the output-side supply, peak source and sink currents, and propagation delay with the power switch’s gate-drive requirements. Toshiba TLP152 ↗
- Photovoltaic
- Check open-circuit voltage and short-circuit photocurrent at the specified LED current when evaluating an external MOSFET gate. Toshiba TLP3905 ↗
Board fit & ordering codes
Match the pinout before approving a substitute
Compare the original and proposed datasheets side by side. A shared pin count can hide different terminal functions, lead forms or isolation spacing.
Input & output
Use the top-view drawing to identify each terminal. Check input polarity where applicable, then map the collector and emitter, logic output, gate-drive, triac or photovoltaic terminals shown for that part.
Body & leads
Check the package drawing, lead span, pitch and mounting style. Match surface-mount pads or through-hole spacing to the actual board.
Barrier spacing
Compare creepage along the package surface and clearance through air. Check the package option and the board layout against the design requirements.
Full suffix
Record the CTR bin, lead form, packing suffix and any approval option. Tape-and-reel codes may appear in the ordering code even when the package marking omits them.
Optocoupler package examples
Images show package appearance. Use the manufacturer’s drawing for dimensions and pin assignments.
Selection FAQ
Optocoupler sourcing questions
Do optocoupler and photocoupler refer to the same component?
Both names describe a component that uses light to carry a signal across an insulation barrier. An opto-isolator can have a transistor, logic or triac output, so name the output circuit in your RFQ.
Can I compare two CTR percentages directly?
Compare values for the same IF, VCE and ambient temperature, then check whether the figures are specified limits or typical values. The ordering suffix may select a particular CTR bin.
Can I use the isolation test voltage as a continuous rating?
Use the specified working or repetitive voltage rating and the associated insulation conditions for continuous operation. The withstand voltage applies to a stated dielectric test and duration.
When does zero-cross switching matter?
A zero-cross phototriac enables triggering close to an AC voltage crossing. Random-phase devices permit triggering elsewhere in the cycle when their input and output conditions are met. Match the part to the control method.
Does the same DIP or SOP name establish pin compatibility?
Check the exact drawing and pin table. Confirm the top-view orientation, all input and output leads, lead form, channel arrangement and the board-side spacing before approving a replacement.
Why do some catalog fields say “See datasheet”?
The product listing has no explicit specification in that field. Open the datasheet for the full manufacturer part number or include the requirement in your inquiry.
How do I request an unlisted part or a particular CTR bin?
Enter the complete manufacturer ordering code and quantity in the RFQ builder. Add the bin and test conditions in the project notes, or attach a BOM through the inquiry form.
How do I submit my RFQ list?
Copy the text or download the TXT file, open the inquiry form, then paste the list or attach the file and submit. Quotes, availability and lead times are confirmed for that request.
Exact MPN · Quantity · Requirements
Prepare your optocoupler RFQ.
Add catalog products or enter a full ordering code. Copy or download the list, then submit it on our inquiry page.
Parts & quantities
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Requirements & inquiry text
Add a part and enter a quantity to prepare your request.
Open inquiry form ↗
Paste the copied text or attach your TXT or BOM on the inquiry form, then submit it there.
Pricing, availability, lead time, documentation and substitutions are confirmed for the specific sourcing request.