LTST-T680UBKT Equivalent & Substitute Parts

Part Overview

The LTST-T680UBKT is a blue 470nm LED indicator in 2-PLCC surface mount package, rated at 3.2V forward voltage with 392mcd brightness. This part is discontinued at DiGi Electronics, necessitating identification of functionally equivalent alternatives that maintain electrical and mechanical compatibility for direct board-level substitution.

Substiute Parts

LTST-T680UBKT

Lite-On Inc.In Stock: 739LTST-T680UBKT Datasheet

Current PartRFQ

LTST-T680UBWT

LITEONIn Stock: 23422LTST-T680UBWT Datasheet

DirectRFQ

150141BS73100

Würth ElektronikIn Stock: 2367150141BS73100 Datasheet

MFR RecommendedRFQ

APED3528VBC/D

KingbrightIn Stock: 20849APED3528VBC/D Datasheet

MFR RecommendedRFQ

SML-LX2832USBC-TR

Lumex Opto/Components Inc.In Stock: 4483SML-LX2832USBC-TR Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility is determined by the following critical parameters:

• Color and Wavelength: All substitutes must be blue LEDs with dominant wavelength at 470nm to maintain optical consistency
• Electrical Compatibility: Forward voltage (Vf) must be within ±0.2V of the original 3.2V specification to ensure circuit compatibility without redesign
• Test Current: All parts operate at 20mA test current
• Mounting Type: Surface mount configuration required for PCB compatibility
• RoHS and MSL Compliance: All substitutes must maintain ROHS3 compliance and MSL 3 rating for manufacturing process compatibility

Substitutes are grouped into two categories:

Category A - Direct 2-PLCC Package Match: LTST-T680UBWT and SML-LX2832USBC-TR maintain identical package footprint and pin configuration, enabling direct board-level replacement without layout modification.

Category B - Alternative Package (3528 Metric): APED3528VBC/D and 150141BS73100 use 1411 (3528 Metric) package, requiring PCB footprint redesign but offering equivalent electrical performance.

Parameter Comparison

Engineering Selection Recommendations

For Direct Board-Level Replacement (No Layout Modification)

LTST-T680UBWT is the primary substitute. It maintains identical 2-PLCC package footprint, matching forward voltage (3.2V), and equivalent viewing angle (120°). Higher brightness (495mcd vs 392mcd) provides improved visibility margin. Active product status ensures long-term availability. Diffused lens transparency differs from the original clear lens but maintains functional compatibility for indication applications.

SML-LX2832USBC-TR offers alternative 2-PLCC compatibility with slightly lower forward voltage (3.1V) and significantly reduced brightness (126mcd). Use only where lower brightness is acceptable or required. Active status supports supply continuity.

For Applications Permitting PCB Redesign

150141BS73100 (Würth Elektronik) provides 3528 metric package with matching 3.2V forward voltage and 120° viewing angle. Brightness (270mcd) falls between original and LTST-T680UBWT specifications. Active product status and established supply chain support production requirements.

APED3528VBC/D (Kingbright) offers highest brightness (550mcd) in 3528 package but introduces three design constraints: forward voltage increase to 3.3V, narrowed viewing angle (40° vs 120°), and increased height (3.20mm vs 2.00mm original). Select only where these parameters align with application requirements.

All substitutes maintain ROHS3 compliance and MSL 3 rating, ensuring manufacturing process compatibility with the original specification.

Frequently Asked Questions (FAQ)

Q: Can LTST-T680UBWT replace LTST-T680UBKT without PCB modification?

A: Yes. Both use identical 2-PLCC package with matching footprint and pin configuration. Forward voltage is identical at 3.2V. The primary difference is lens transparency (diffused vs clear), which does not affect electrical compatibility or board-level installation.

Q: What is the impact of forward voltage variation in substitute parts?

A: Forward voltage tolerance of ±0.2V is acceptable for LED indicator circuits. LTST-T680UBWT (3.2V) and 150141BS73100 (3.2V) match the original exactly. SML-LX2832USBC-TR (3.1V) operates within tolerance. APED3528VBC/D (3.3V) requires circuit verification to confirm current-limiting resistor adequacy, as higher Vf reduces voltage drop across the resistor.

Q: Why do some substitutes have different brightness ratings?

A: Millicandela rating depends on LED die efficiency, lens design, and optical properties. Substitutes with higher brightness (LTST-T680UBWT at 495mcd, APED3528VBC/D at 550mcd) provide improved visibility. Lower brightness (SML-LX2832USBC-TR at 126mcd) may require application verification. All operate at identical 20mA test current.

Q: What is the significance of viewing angle differences?

A: Viewing angle determines the cone of light distribution. The original LTST-T680UBKT and most substitutes maintain 120° viewing angle for wide-angle indication. APED3528VBC/D narrows this to 40°, suitable only for directed viewing applications. Verify application requirements before selection.

Q: Can 3528 metric package parts replace 2-PLCC directly?

A: No. 3528 metric (1411) and 2-PLCC packages have different footprints and dimensions. 150141BS73100 and APED3528VBC/D require PCB layout redesign. Use only when PCB modification is feasible. Direct replacement without layout change requires 2-PLCC package parts (LTST-T680UBWT or SML-LX2832USBC-TR).

Q: Are all substitutes RoHS and MSL compliant?

A: Yes. All listed substitutes maintain ROHS3 compliance and MSL 3 (168 Hours) rating, matching the original specification. Manufacturing process compatibility is preserved across all alternatives.

Q: Which substitute offers the best long-term availability?

A: LTST-T680UBWT (LITEON) and APED3528VBC/D (Kingbright) show highest inventory levels (23,402 and 20,793 units respectively) and active product status, supporting sustained production requirements. 150141BS73100 (Würth Elektronik) and SML-LX2832USBC-TR (Lumex) maintain active status with adequate stock for standard lead times.