LTL-4291 Red Diffused T-1 LED Equivalent & Substitute Parts

Part Overview

The LTL-4291 is a red diffused T-1 through-hole LED manufactured by Lite-On Inc., designed for indication applications. This part features a 3mm round domed lens with 12.6mcd brightness at 2V forward voltage and 20mA test current. The LTL-4291 is currently active in production with full RoHS3 compliance and unlimited moisture sensitivity rating.

Substitute parts are necessary when the original LTL-4291 becomes unavailable, when alternative packaging formats are required, or when design specifications allow for compatible alternatives with different electrical characteristics. The following parts maintain mechanical compatibility (T-1 through-hole mounting, 3mm form factor) while offering variations in forward voltage, brightness, and wavelength specifications.

Key Parameters

Parameter	LTL-4291 Specification
Manufacturer	Lite-On Inc.
Color	Red
Lens Size	3mm, T-1
Lens Style	Round with Domed Top
Lens Transparency	Diffused
Mounting Type	Through Hole
Voltage - Forward (Vf) Typical	2V
Current - Test	20mA
Millicandela Rating	12.6mcd
Wavelength - Dominant	621nm
Wavelength - Peak	630nm
Viewing Angle	40°
Height Maximum	6.55mm
Package / Case	Radial
Product Status	Active
RoHS Status	RoHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution compatibility for the LTL-4291 is determined by the following critical parameters:

Mechanical Compatibility Requirements:

Lens size: 3mm, T-1 form factor
Lens style: Round with domed top
Mounting type: Through hole radial configuration
Height maximum: Must fit within PCB clearance constraints

Electrical Compatibility Considerations:

Forward voltage (Vf): Determines circuit design requirements and current-limiting resistor values
Test current: Defines brightness output at specified operating conditions
Millicandela rating: Brightness intensity for indication visibility
Wavelength dominant and peak: Color perception and optical filtering compatibility

Regulatory & Environmental Compliance:

RoHS3 compliance status
Moisture sensitivity level (MSL)
Product status (Active vs. Obsolete vs. Not For New Designs)

Substitute parts listed below maintain the T-1 through-hole mechanical form factor and red color specification. Electrical parameters vary to accommodate different circuit voltage requirements and brightness needs. All listed substitutes are RoHS3 compliant with MSL 1 rating.

Parameter Comparison

Part Number	Manufacturer	Vf (Typ)	Test Current	Millicandela	Wavelength Dominant	Viewing Angle	Height Max	Product Status	Packaging
LTL-4291	Lite-On Inc.	2V	20mA	12.6mcd	621nm	40°	6.55mm	Active	Bulk
151031SS06000	Würth Elektronik	2.2V	20mA	35mcd	640nm	60°	5.55mm	Active	Bulk
4300F1LC	Visual Communications Company - VCC	1.8V	2mA	1.8mcd	—	50°	6.35mm	Not For New Designs	Bulk
HLMP-1600	Broadcom Limited	5V	10mA	2.1mcd	626nm	60°	6.35mm	Active	Bulk
HLMP-1601	Broadcom Limited	12V	13mA	2.1mcd	626nm	60°	6.35mm	Active	Bulk
HLMP-1700	Broadcom Limited	1.7V	2mA	2.1mcd	626nm	50°	6.35mm	Active	Bulk
HLMP-1700-B0002	Broadcom Limited	1.7V	2mA	2.1mcd	626nm	50°	6.35mm	Active	Cut Tape (CT)
HLMP-K101	Broadcom Limited	1.8V	20mA	45mcd	637nm	60°	6.35mm	Active	Bulk
HLMP-K150	Broadcom Limited	1.7V	1mA	2mcd	640nm	60°	6.35mm	Active	Bulk
HLMP-K150-C0002	Broadcom Limited	1.7V	1mA	2mcd	640nm	60°	6.35mm	Active	Cut Tape (CT)
MV5774C	onsemi	2V	20mA	9mcd	—	90°	5.84mm	Obsolete	—

Engineering Selection Recommendations

For Active Production Designs:

Select from parts with Active product status: 151031SS06000, HLMP-1600, HLMP-1601, HLMP-1700, HLMP-1700-B0002, HLMP-K101, HLMP-K150, or HLMP-K150-C0002. All maintain RoHS3 compliance and MSL 1 rating.

For 2V Forward Voltage Circuits (Direct Electrical Match):

The LTL-4291 operates at 2V typical forward voltage. The 151031SS06000 (Würth Elektronik) operates at 2.2V and maintains 20mA test current, making it suitable for circuits with slight voltage tolerance. The MV5774C (onsemi) matches 2V and 20mA specifications but carries Obsolete status and should not be selected for new designs.

For Low-Voltage Applications (1.7V to 1.8V):

HLMP-1700, HLMP-1700-B0002, HLMP-K150, and HLMP-K150-C0002 operate at 1.7V. HLMP-K101 operates at 1.8V with 20mA test current and 45mcd brightness, providing higher intensity than the LTL-4291 at comparable voltage. The 4300F1LC (VCC) operates at 1.8V but carries Not For New Designs status.

For Higher Voltage Requirements (5V to 12V):

HLMP-1600 (5V) and HLMP-1601 (12V) accommodate higher supply voltages with reduced test current (10mA and 13mA respectively) and lower brightness (2.1mcd). These are suitable for circuits requiring higher voltage operation.

For Brightness-Critical Applications:

The 151031SS06000 provides 35mcd brightness at 2.2V and 20mA, exceeding the LTL-4291 specification of 12.6mcd. The HLMP-K101 provides 45mcd at 1.8V and 20mA. Both are active production parts suitable for applications requiring enhanced visibility.

For Packaging Flexibility:

HLMP-1700-B0002 and HLMP-K150-C0002 are available in Cut Tape (CT) packaging, offering alternative supply formats to the standard Bulk packaging of the LTL-4291.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with different forward voltage in my existing circuit?

A: Forward voltage differences require circuit redesign. If your circuit uses a fixed current-limiting resistor calculated for 2V, substituting a 1.7V part will increase LED current and brightness; substituting a 5V part will reduce current and brightness. Recalculate the current-limiting resistor value for the new forward voltage to maintain proper operation.

Q: What is the difference between HLMP-1700 and HLMP-1700-B0002?

A: Both parts are electrically and mechanically identical (1.7V, 2mA test current, 2.1mcd, 626nm dominant wavelength, 6.35mm height). The difference is packaging format: HLMP-1700 is supplied in Bulk packaging, while HLMP-1700-B0002 is supplied in Cut Tape (CT) format. Select based on your assembly process requirements.

Q: Is the 151031SS06000 a direct replacement for the LTL-4291?

A: The 151031SS06000 maintains mechanical compatibility (3mm T-1 through-hole) and similar test current (20mA), but operates at 2.2V instead of 2V and provides higher brightness (35mcd vs. 12.6mcd). It is electrically compatible with circuits designed for 2V operation with minor voltage tolerance, but verify your circuit design allows for the increased brightness output.

Q: Why should I avoid the MV5774C and 4300F1LC?

A: The MV5774C carries Obsolete product status, indicating discontinued manufacturing and limited future availability. The 4300F1LC carries Not For New Designs status, indicating the manufacturer recommends against use in new product development. Both should be avoided for new designs; use only if legacy product support is required.

Q: Can I substitute a part with a wider viewing angle?

A: Yes, if your application permits. The LTL-4291 has a 40° viewing angle. Substitutes with 50°, 60°, or 90° viewing angles provide wider light distribution. Verify that the increased viewing angle does not compromise the intended indication visibility or create undesired light spillover in your application.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts carry RoHS3 Compliant status and MSL 1 (Unlimited) moisture sensitivity rating, matching the environmental compliance profile of the LTL-4291.

Q: Which substitute offers the closest electrical match to the LTL-4291?

A: The 151031SS06000 (Würth Elektronik) provides the closest electrical match with 2.2V forward voltage and 20mA test current, differing only 0.2V from the LTL-4291 specification. For applications with strict voltage matching requirements, this part is the primary recommendation among active production alternatives.

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