MR3751 LED Red Diffused T-1 3/4 Through Hole - Equivalent & Substitute Parts

Part Overview

The onsemi MR3751 is a red diffused LED indicator designed for through-hole mounting in 5mm T-1 3/4 form factor. This component is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. The MR3751 operates at 12V forward voltage with a 4mcd brightness rating and 60° viewing angle, serving as a discrete red indication element in electronic assemblies.

Key Parameters

Parameter	MR3751 Value
Manufacturer	onsemi
Color	Red
Lens Transparency	Diffused
Lens Size	5mm, T-1 3/4
Voltage - Forward (Vf) (Typ)	12V
Current - Test	13mA
Millicandela Rating	4mcd
Viewing Angle	60°
Mounting Type	Through Hole
Wavelength - Peak	635nm
Height (Max)	11.56mm
Package / Case	Radial
Product Status	Obsolete
RoHS Status	RoHS non-compliant

Substitute Part Grouping Explanation

Substitution of the MR3751 is determined by the following critical parameters:

Form Factor & Mounting Compatibility: Lens size (5mm, T-1 3/4), mounting type (through hole), and package configuration (radial) must match to ensure mechanical fit in existing PCB layouts.

Electrical Compatibility: Forward voltage (Vf), test current, and wavelength characteristics determine circuit integration feasibility. The MR3751 operates at 12V, which is significantly higher than most standard red LEDs (typically 1.9V to 5V). Substitutes must be evaluated for voltage compatibility within the application circuit.

Optical Characteristics: Color (red), lens transparency (diffused), viewing angle (60°), and brightness (millicandela rating) define the visual performance and indication visibility.

Regulatory Compliance: RoHS status and REACH compliance affect suitability for new designs and regulated markets. The MR3751 is RoHS non-compliant, whereas active substitutes are ROHS3 compliant.

Substitute parts are grouped by their ability to maintain these parameters within acceptable engineering tolerances for the intended application.

Parameter Comparison

Parameter	MR3751	333-2SDRD/S530-A3	HLMP-3301	HLMP-3301-D0000	HLMP-3301-D0001	HLMP-3301-D0002	HLMP-3600
Manufacturer	onsemi	Everlight Electronics Co Ltd	Broadcom Limited	Broadcom Limited	Broadcom Limited	Broadcom Limited	Broadcom Limited
Color	Red	Red	Red	Red	Red	Red	Red
Lens Transparency	Diffused	Diffused	Diffused	Diffused	Diffused	Diffused	Diffused
Lens Size	5mm, T-1 3/4	5.00mm Dia	5mm, T-1 3/4	5mm, T-1 3/4	5mm, T-1 3/4	5mm, T-1 3/4	5mm, T-1 3/4
Voltage - Forward (Vf) (Typ)	12V	2V	1.9V	1.9V	1.9V	1.9V	5V
Current - Test	13mA	20mA	10mA	10mA	10mA	10mA	10mA
Millicandela Rating	4mcd	160mcd	5.4mcd	2.1mcd	2.1mcd	2.1mcd	2.1mcd
Viewing Angle	60°	30°	60°	60°	60°	60°	60°
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Wavelength - Peak	635nm	650nm	635nm	635nm	635nm	635nm	635nm
Height (Max)	11.56mm	8.90mm	9.19mm	9.19mm	9.19mm	9.19mm	9.19mm
Package / Case	Radial	Radial	Radial	Radial	Radial	Radial	Radial
Product Status	Obsolete	Active	Active	Active	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Primary Substitutes for Form Factor Match (5mm T-1 3/4, 60° Viewing Angle):

The HLMP-3301 series from Broadcom Limited provides the closest mechanical and optical compatibility with the MR3751. These parts maintain the 5mm T-1 3/4 lens form factor, 60° viewing angle, and diffused red lens characteristics. All HLMP-3301 variants are ROHS3 compliant and active products, addressing the obsolescence and regulatory compliance limitations of the MR3751.

Voltage Consideration:

The MR3751 operates at 12V forward voltage, which is substantially higher than standard red LEDs. The HLMP-3301 series operates at 1.9V, and the HLMP-3600 operates at 5V. Circuit redesign or the addition of current-limiting resistors will be required when substituting the MR3751 with lower-voltage alternatives. The HLMP-3600 at 5V may require less circuit modification than the 1.9V HLMP-3301 series, depending on the application's power supply architecture.

Brightness Consideration:

The MR3751 provides 4mcd brightness. The HLMP-3301 variants offer either 5.4mcd or 2.1mcd depending on the specific part number suffix. The HLMP-3600 provides 2.1mcd. Brightness differences are within typical indicator application tolerances but should be verified against visual indication requirements.

Packaging Variants:

HLMP-3301 variants are available in Bulk, Tape & Reel (TR), and Cut Tape (CT) packaging. Selection depends on production volume and assembly process requirements. The HLMP-3301-D0002 and HLMP-3301-F00DD offer the highest inventory availability in Cut Tape format.

Alternative for Different Viewing Angle:

The Everlight 333-2SDRD/S530-A3 maintains 5mm form factor and through-hole mounting but features a 30° viewing angle (narrower than the MR3751's 60°) and significantly higher brightness (160mcd). This part is suitable only if the application can accommodate the narrower viewing angle and higher brightness output.

Frequently Asked Questions (FAQ)

Q: Can I directly replace the MR3751 with an HLMP-3301 without circuit modifications?

A: No. The MR3751 operates at 12V forward voltage, while the HLMP-3301 operates at 1.9V. Direct substitution requires circuit redesign to accommodate the lower voltage requirement. Current-limiting resistor values must be recalculated based on the new forward voltage and the application's power supply voltage.

Q: What is the primary reason the MR3751 is being discontinued?

A: The MR3751 is classified as obsolete. Active alternatives from major manufacturers like Broadcom Limited (HLMP-3301 series) and Everlight Electronics provide equivalent or superior performance with ROHS3 compliance and ongoing production support.

Q: Are all HLMP-3301 variants electrically identical?

A: HLMP-3301 variants differ in brightness rating and packaging format. The base HLMP-3301 and HLMP-3301-F0002 provide 5.4mcd, while HLMP-3301-D0000, HLMP-3301-D0001, and HLMP-3301-D0002 provide 2.1mcd. All operate at 1.9V forward voltage and 10mA test current. Packaging variants (Bulk, Tape & Reel, Cut Tape) do not affect electrical performance.

Q: Does the MR3751's greater height (11.56mm vs. 9.19mm for HLMP-3301) affect substitution?

A: The MR3751 is taller than most HLMP-3301 variants. If the PCB layout has height constraints, the shorter HLMP-3301 series may provide design advantages. However, if the original design accommodates the MR3751's height, the HLMP-3301's shorter profile will not cause mechanical interference.

Q: Is the 333-2SDRD/S530-A3 a suitable substitute if viewing angle is not critical?

A: The 333-2SDRD/S530-A3 maintains 5mm form factor and through-hole mounting but operates at 2V forward voltage and features a 30° viewing angle (compared to the MR3751's 60°). It is suitable only if the application's optical requirements can accommodate the narrower viewing angle and higher brightness (160mcd). Circuit modifications for the 2V forward voltage are required.

Q: What packaging format should I select for the HLMP-3301 series?

A: Packaging selection depends on production volume and assembly process. Bulk packaging suits lower-volume or manual assembly. Tape & Reel (TR) and Cut Tape (CT) formats are optimized for automated pick-and-place assembly. The HLMP-3301-F00DD in Cut Tape format offers the highest inventory availability (43,381 pcs).

Q: Are all substitute parts RoHS compliant?

A: Yes. All listed substitute parts (HLMP-3301 series, HLMP-3600, and 333-2SDRD/S530-A3) are ROHS3 compliant. The MR3751 is RoHS non-compliant, making compliant substitutes necessary for new designs targeting regulated markets.

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