LY521 Yellow LED T-1 3/4 Through Hole - Equivalent & Substitute Parts

Part Overview

The LY521 is a yellow 590nm LED indication component manufactured by Seoul Semiconductor Inc., designed for through-hole mounting applications. This discrete 2V radial LED features a 5.00mm round domed lens and delivers 7500mcd brightness at 20mA test current. The product is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing design support and component procurement.

Substiute Parts

LY521

Seoul Semiconductor Inc.In Stock: 946LY521 Datasheet

Current PartRFQ

383-2UYC/S400-A6

Everlight Electronics Co LtdIn Stock: 1149383-2UYC/S400-A6 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the LY521 is determined by strict alignment of the following critical parameters:

• Color and Wavelength: Yellow indication function requires dominant wavelength in the 589-590nm range
• Electrical Characteristics: Forward voltage of 2V and test current of 20mA must be maintained for circuit compatibility
• Mechanical Form Factor: 5.00mm round lens diameter and through-hole radial mounting are required for PCB fit
• Optical Performance: Millicandela rating and viewing angle determine brightness and visibility characteristics
• Package Configuration: T-1 3/4 or equivalent 5.0mm round through-hole package ensures direct mechanical substitution

The substitute part 383-2UYC/S400-A6 (Everlight Electronics Co Ltd) meets these core substitution criteria across all critical parameters.

Parameter Comparison

Engineering Selection Recommendations

The 383-2UYC/S400-A6 from Everlight Electronics Co Ltd is a direct functional substitute for the obsolete LY521. Both components share identical electrical specifications (2V forward voltage, 20mA test current) and mechanical form factors (5.00mm round through-hole radial package), ensuring circuit and PCB compatibility without redesign.

The substitute part offers the following advantages:

• Active Product Status: Currently manufactured and in production, ensuring long-term availability
• Enhanced Brightness: 8000mcd rating provides 6.7% higher luminous intensity than the original 7500mcd specification
• Regulatory Compliance: ROHS3 compliant, meeting current environmental and material restriction standards
• Reduced Height: 8.90mm maximum height versus 9.90mm original, providing improved PCB layout flexibility

The narrower viewing angle of 6° on the substitute (versus 22° on the original) represents the primary optical difference. This characteristic should be evaluated against specific application requirements for indicator visibility and directional light distribution.

Frequently Asked Questions (FAQ)

Q: Can the 383-2UYC/S400-A6 be used as a direct replacement for the LY521 without circuit modification?

A: Yes. Both components operate at 2V forward voltage with 20mA test current and share identical 5.00mm round through-hole radial package geometry. No circuit or PCB layout changes are required for electrical or mechanical substitution.

Q: What is the significance of the viewing angle difference between the two parts?

A: The LY521 provides a 22° viewing angle, while the 383-2UYC/S400-A6 offers a 6° viewing angle. This means the substitute produces a more focused, directional light output. Applications requiring wide-angle indicator visibility should evaluate whether the narrower beam pattern meets functional requirements.

Q: Why is the LY521 listed as obsolete?

A: Product obsolescence indicates the component is no longer manufactured by Seoul Semiconductor Inc. The 383-2UYC/S400-A6 substitute ensures continued availability for designs currently using or requiring yellow 590nm LED indication in T-1 3/4 through-hole packages.

Q: Are there compliance differences between the original and substitute part?

A: The 383-2UYC/S400-A6 carries ROHS3 compliance certification, confirming adherence to current material restriction directives. The original LY521 compliance status is not specified in available documentation.

Q: Does the 1mm height difference affect PCB assembly?

A: The substitute part is 1.00mm shorter (8.90mm versus 9.90mm maximum height). This reduction provides additional clearance in space-constrained applications and does not create compatibility issues. Verify final assembly height against specific PCB design constraints if critical.

Q: What wavelength range is acceptable for yellow LED substitution?

A: For yellow indication applications, dominant wavelengths between 589-590nm are functionally equivalent. Both the LY521 (590nm) and 383-2UYC/S400-A6 (589nm) fall within this range and produce visually indistinguishable yellow light output.