3YD-F Yellow LED Equivalent & Substitute Parts

Part Overview

The Bivar 3YD-F is an active, through-hole yellow LED indicator in T-1 (3mm) form factor with diffused lens, designed for discrete 2V yellow light indication applications. The component is ROHS3 compliant with MSL-1 rating, making it suitable for standard electronic assembly environments. Identifying equivalent and substitute parts is necessary when the primary part experiences supply constraints, when alternative specifications better match system requirements, or when sourcing from multiple suppliers is required for manufacturing continuity.

Key Parameters

Parameter	Specification
Manufacturer Part Number	3YD-F
Manufacturer	Bivar Inc.
Color	Yellow
Lens Transparency	Diffused
Lens Size	3mm, T-1
Voltage - Forward (Vf)	2V (Typ)
Current - Test	20mA
Millicandela Rating	20mcd
Viewing Angle	35°
Mounting Type	Through Hole
Wavelength - Peak	590nm
Package / Case	Radial
RoHS Status	ROHS3 Compliant
MSL Rating	1 (Unlimited)
Product Status	Active

Substitute Part Grouping Explanation

Substitution eligibility for the 3YD-F is determined by the following critical parameters: color (yellow), lens transparency (diffused), lens size (3mm T-1), mounting type (through hole), forward voltage range (2V ±0.2V), test current compatibility (10-20mA), and package type (radial). Parts meeting these core electrical and mechanical criteria are classified as direct substitutes. Parts with deviations in forward voltage (>0.2V variance), different lens transparency, or significantly reduced brightness at operating current are classified as conditional substitutes requiring circuit design verification. Parts with color, lens size, or mounting type differences are classified as non-equivalent and excluded from substitution eligibility.

Parameter Comparison

Part Number	Manufacturer	Color	Vf (Typ)	Current (Test)	mcd	Viewing Angle	Wavelength (Peak)	Height (Max)	RoHS Status
3YD-F	Bivar Inc.	Yellow	2V	20mA	20	35°	590nm	5.30mm	ROHS3
151031YS05900	Würth Elektronik	Yellow	2.1V	20mA	30	60°	585nm	5.55mm	ROHS3
HLMP-1620	Broadcom Limited	Yellow	5V	10mA	2.2	60°	583nm	6.35mm	ROHS3
HLMP-1621	Broadcom Limited	Yellow	12V	13mA	2.2	60°	583nm	6.35mm	ROHS3
HLMP-1719	Broadcom Limited	Yellow	1.8V	2mA	2.1	50°	585nm	6.35mm	ROHS3
HLMP-1719-A0002	Broadcom Limited	Yellow	1.8V	2mA	2.1	50°	585nm	6.35mm	ROHS3
LTL-4251	Lite-On Inc.	Yellow	2.1V	10mA	8.7	40°	585nm	6.55mm	ROHS3
LTL-4251N	Lite-On Inc.	Yellow	2.1V	10mA	5.6	60°	585nm	5.85mm	ROHS3

Engineering Selection Recommendations

Direct Substitutes (Compatible with 3YD-F circuit designs):

151031YS05900 (Würth Elektronik): Operates at 2.1V forward voltage within acceptable tolerance, supports 20mA test current, and delivers higher brightness (30mcd). ROHS3 compliant. Wider viewing angle (60°) may require circuit layout review. REACH Unaffected status provides full regulatory compliance.
LTL-4251 (Lite-On Inc.): Operates at 2.1V forward voltage, supports 10mA-20mA current range, delivers intermediate brightness (8.7mcd). ROHS3 compliant. REACH Affected status requires compliance verification in supply chain. Compatible with 3YD-F electrical interface.
LTL-4251N (Lite-On Inc.): Operates at 2.1V forward voltage, supports 10mA current, delivers intermediate brightness (5.6mcd). ROHS3 compliant. REACH Unaffected. Compact height (5.85mm) near original specification.

Conditional Substitutes (Require circuit modification or system evaluation):

HLMP-1620 (Broadcom Limited): Forward voltage of 5V requires external series resistor redesign or different power supply. Test current reduced to 10mA. Very low brightness (2.2mcd) limits visibility. Use only in high-ambient-light rejection applications or when 5V supply is standard. ROHS3 and REACH compliant.
HLMP-1621 (Broadcom Limited): Forward voltage of 12V requires significant circuit redesign. Test current 13mA. Very low brightness (2.2mcd). Use only when designed for 12V direct supply operation. ROHS3 and REACH compliant.
HLMP-1719 / HLMP-1719-A0002 (Broadcom Limited): Forward voltage of 1.8V is within tolerance, but extremely low test current (2mA) requires circuit modification. Very low brightness (2.1mcd) unsuitable for brightness-critical applications. Use only in low-current indicator circuits. ROHS3 and REACH compliant.

Not Recommended: Orange-colored alternatives (SLI-343D8C3F, SLI-343D8U3F) differ in wavelength and color, making them incompatible with yellow-specific applications.

Frequently Asked Questions (FAQ)

Q: Can I use HLMP-1620 as a direct drop-in replacement? A: No. The HLMP-1620 operates at 5V forward voltage compared to the 3YD-F's 2V specification. Direct substitution will cause excessive current draw or component failure. Circuit redesign is required, specifically modification of the series current-limiting resistor to accommodate the 5V forward voltage and 10mA test current.

Q: What is the primary difference between the 3YD-F and 151031YS05900? A: The 151031YS05900 operates at 2.1V forward voltage (0.1V higher) and delivers 30mcd brightness compared to the 3YD-F's 20mcd. Both support 20mA test current and are mechanically compatible. The Würth part offers 50% higher brightness and wider viewing angle (60° vs 35°), suitable for applications requiring improved visibility.

Q: Are LTL-4251 and LTL-4251N interchangeable? A: Both operate at identical electrical specifications (2.1V, 2.1V forward voltage), but differ in brightness (8.7mcd vs 5.6mcd) and viewing angle (40° vs 60°). Select based on brightness requirements and optical coverage area needed. The -N variant provides wider viewing angle.

Q: Can packaging format be different between the main part and substitute? A: The main part and all listed yellow equivalents use T-1 3mm radial through-hole packages. Packaging variations in some parts (e.g., HLMP-1719-A0002 in cut tape vs HLMP-1719 in bulk) do not affect electrical compatibility, only supply chain handling and minimum order quantities.

Q: What does ROHS3 compliance mean for substitution? A: ROHS3 compliance indicates the part meets Restriction of Hazardous Substances directive requirements, restricting lead and other hazardous materials. All listed substitutes are ROHS3 compliant, ensuring environmental and regulatory compatibility with original design specifications.

Q: Why is forward voltage important when selecting a substitute? A: Forward voltage determines the voltage drop across the LED during operation. The 3YD-F operates at 2V. Substitutes with significantly higher forward voltage (HLMP-1620 at 5V, HLMP-1621 at 12V) require redesigned current-limiting circuits. Substitutes within 0.1V-0.2V variance maintain compatibility with existing resistor values.

Q: What is the significance of millicandela (mcd) rating? A: Millicandela rating indicates brightness at the specified test current. The 3YD-F produces 20mcd at 20mA. Higher mcd ratings (151031YS05900 at 30mcd) indicate brighter operation; lower ratings (HLMP-1620 at 2.2mcd) indicate dimmer operation. Application visibility requirements determine acceptable mcd ranges.

Q: Can I use a substitute with different test current? A: Test current specifications indicate the LED's designed operating point. Substitutes with identical or higher test current ratings (e.g., 20mA → 10mA) generally function correctly but may produce different brightness levels. Substitutes designed for much lower test current (e.g., HLMP-1719 at 2mA) are unsuitable for 20mA circuits without specific brightness-independent application requirements.

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