LTW-77HC4 Equivalent & Substitute Parts

Part Overview

The LTW-77HC4 is a white LED indication component manufactured by Lite-On Inc., designed for through-hole radial mounting applications. This part is classified as obsolete, making identification of functionally equivalent alternatives necessary for ongoing design support and procurement continuity. The LTW-77HC4 delivers 140 millicandela brightness with a 3.5V forward voltage and 140° viewing angle in a 3.00mm diameter round lens configuration.

Substiute Parts

LTW-77HC4

Lite-On Inc.In Stock: 903LTW-77HC4 Datasheet

Current PartRFQ

LTW-87HD4B

Lite-On Inc.In Stock: 1117LTW-87HD4B Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

The LTW-87HD4B qualifies as a functional substitute based on the following alignment of critical electrical and mechanical parameters:

Matching Parameters:

• Color: White
• Lens Transparency: Clear
• Millicandela Rating: 140mcd (identical brightness)
• Current - Test: 20mA (identical test current)
• Mounting Type: Through Hole (identical mounting)
• Package / Case: Radial (identical package type)
• Manufacturer: Lite-On Inc. (same manufacturer)

Acceptable Variations:

• Voltage - Forward (Vf): 3.5V (main part) vs. 3.3V (substitute) — within typical LED forward voltage tolerance for white LEDs
• Viewing Angle: 140° (main part) vs. 130° (substitute) — minor reduction in viewing angle
• Lens Size: 3.00mm (main part) vs. 3mm T-1 (substitute) — standard T-1 package equivalent
• Height (Max): 3.20mm (main part) vs. 3.95mm (substitute) — acceptable height difference for through-hole applications

Parameter Comparison

Engineering Selection Recommendations

The LTW-87HD4B is the manufacturer-recommended substitute for the obsolete LTW-77HC4. Selection of this substitute is supported by:

• Product Status Alignment: The LTW-87HD4B maintains active production status, ensuring long-term availability and supply chain continuity.
• Compliance Enhancement: The substitute achieves ROHS3 compliance, whereas the main part does not specify compliance status.
• Improved Moisture Handling: MSL rating of 1 (Unlimited) provides superior moisture resistance compared to the main part's MSL 2 (1 Year) rating.
• Electrical Compatibility: Forward voltage difference of 0.2V is within acceptable tolerance for white LED applications and does not require circuit redesign.
• Optical Performance: Identical brightness rating (140mcd) and minor viewing angle reduction (10° difference) maintain functional equivalence for indication applications.

Frequently Asked Questions (FAQ)

Q: Can the LTW-87HD4B be used as a direct replacement for the LTW-77HC4 without circuit modification?

A: Yes. The 0.2V forward voltage difference (3.5V vs. 3.3V) is within standard white LED tolerance and does not require circuit redesign. Both parts operate at identical test current (20mA) and deliver the same brightness (140mcd).

Q: What is the impact of the 10° viewing angle reduction?

A: The LTW-87HD4B provides 130° viewing angle compared to the LTW-77HC4's 140°. For indication applications, this reduction is acceptable. Applications requiring the full 140° viewing angle should evaluate alternative parts.

Q: Does the height difference affect PCB layout?

A: The LTW-87HD4B is 0.75mm taller (3.95mm vs. 3.20mm). Verify clearance in your mechanical design. Through-hole mounting remains compatible; adjust lead bending if necessary.

Q: Is the LTW-87HD4B available in the same packaging as the LTW-77HC4?

A: Both parts use radial through-hole packaging. The LTW-87HD4B is supplied in bulk packaging, whereas the LTW-77HC4 packaging type is not specified. Confirm packaging requirements with your procurement process.

Q: What compliance advantages does the LTW-87HD4B offer?

A: The LTW-87HD4B is ROHS3 compliant and carries MSL 1 (Unlimited) moisture sensitivity rating, compared to the main part's unspecified compliance and MSL 2 (1 Year) rating. These certifications support regulatory requirements and long-term storage reliability.