TLLY4401 Equivalent & Substitute Parts

Part Overview

The TLLY4401 is a yellow diffused T-1 through-hole LED manufactured by Vishay Semiconductor Opto Division, designed for indication applications. This part operates at 2.4V forward voltage with a 2mcd brightness rating and 588nm dominant wavelength. The product is active and ROHS3 compliant with unlimited moisture sensitivity rating.

Substitute parts may be required due to inventory constraints, design optimization for brightness or viewing angle requirements, or sourcing from alternative manufacturers while maintaining functional compatibility within the T-1 through-hole LED category.

Key Parameters

Parameter	TLLY4401
Manufacturer	Vishay Semiconductor Opto Division
Color	Yellow
Wavelength - Dominant	588nm
Voltage - Forward (Vf) (Typ)	2.4V
Current - Test	2mA
Millicandela Rating	2mcd
Lens Transparency	Diffused
Viewing Angle	50°
Mounting Type	Through Hole
Package / Case	Radial
Supplier Device Package	T-1
Height (Max)	6.10mm
RoHS Status	ROHS3 Compliant
Product Status	Active

Substitute Part Grouping Explanation

Substitution logic for the TLLY4401 is based on the following criteria:

Primary Substitutes (Yellow LED, Same Color Family):

SLI-343Y8Y3F (Rohm Semiconductor): Yellow diffused T-1 LED with 590nm wavelength, 2.2V forward voltage, 470mcd brightness
WP710A10SYD (Kingbright): Yellow diffused T-1 LED with 590nm wavelength, 2V forward voltage, 900mcd brightness

Secondary Substitutes (Orange LED, Alternative Color):

SLI-343D8U3F (Rohm Semiconductor): Orange diffused T-1 LED with 605nm wavelength, 2.2V forward voltage, 470mcd brightness
SSL-LX3044SOD (Lumex Opto/Components Inc.): Orange diffused T-1 LED with 610nm peak wavelength, 2V forward voltage, 100mcd brightness
WP710A10SED (Kingbright): Orange diffused T-1 LED with 601nm wavelength, 2V forward voltage, 650mcd brightness

All substitute parts maintain the following compatibility parameters:

Through-hole mounting type
T-1 radial package configuration
Diffused lens transparency
ROHS3 compliance
Unlimited moisture sensitivity (MSL 1)
Forward voltage range: 2.0V to 2.4V

Parameter Comparison

Part Number	Manufacturer	Color	Wavelength (nm)	Vf (Typ)	Test Current	Brightness (mcd)	Viewing Angle	Height (Max)	Inventory
TLLY4401	Vishay	Yellow	588	2.4V	2mA	2	50°	6.10mm	4789 Pcs
SLI-343Y8Y3F	Rohm	Yellow	590	2.2V	20mA	470	40°	5.60mm	8965 Pcs
WP710A10SYD	Kingbright	Yellow	590	2.0V	20mA	900	40°	5.90mm	2577 Pcs
SLI-343D8U3F	Rohm	Orange	605	2.2V	20mA	470	40°	5.60mm	1311 Pcs
SSL-LX3044SOD	Lumex	Orange	610	2.0V	20mA	100	60°	4.60mm	949 Pcs
WP710A10SED	Kingbright	Orange	601	2.0V	20mA	650	40°	5.90mm	3621 Pcs

Engineering Selection Recommendations

For Direct Yellow LED Replacement: Select SLI-343Y8Y3F or WP710A10SYD when yellow indication color is required. Both parts are ROHS3 compliant, active products with unlimited moisture sensitivity. SLI-343Y8Y3F offers moderate brightness (470mcd) with 40° viewing angle. WP710A10SYD provides higher brightness (900mcd) at the same viewing angle and lower forward voltage (2.0V).

For Orange LED Substitution: Select from SLI-343D8U3F, SSL-LX3044SOD, or WP710A10SED when color change is acceptable. All are ROHS3 compliant active products. WP710A10SED offers the highest brightness (650mcd) with 40° viewing angle. SSL-LX3044SOD provides the widest viewing angle (60°) with lower brightness (100mcd).

Voltage Compatibility Consideration: The TLLY4401 operates at 2.4V forward voltage. All substitute parts operate at 2.0V to 2.2V forward voltage. Circuit designs must accommodate this lower voltage requirement when substituting.

All substitute parts maintain:

ROHS3 compliance
Active product status
Through-hole T-1 radial package
Diffused lens configuration
Unlimited moisture sensitivity rating

Frequently Asked Questions (FAQ)

Q: Can I substitute the TLLY4401 with an orange LED? A: Yes. Orange LED substitutes (SLI-343D8U3F, SSL-LX3044SOD, WP710A10SED) are electrically compatible within the T-1 through-hole package category. However, this represents a color change from yellow to orange and may affect visual indication in the application.

Q: What is the main difference between yellow substitute options? A: SLI-343Y8Y3F and WP710A10SYD both provide yellow indication at 590nm wavelength. WP710A10SYD offers significantly higher brightness (900mcd vs. 470mcd) and lower forward voltage (2.0V vs. 2.2V). SLI-343Y8Y3F provides moderate brightness with slightly higher forward voltage.

Q: Are all substitute parts ROHS3 compliant? A: Yes. All listed substitute parts are ROHS3 compliant with unlimited moisture sensitivity (MSL 1), matching the compliance profile of the TLLY4401.

Q: What viewing angle differences exist among substitutes? A: The TLLY4401 has a 50° viewing angle. Yellow substitutes (SLI-343Y8Y3F, WP710A10SYD) provide 40° viewing angle. Orange substitutes range from 40° to 60°, with SSL-LX3044SOD offering the widest viewing angle at 60°.

Q: How does forward voltage affect circuit design? A: The TLLY4401 operates at 2.4V forward voltage. Substitute parts operate at 2.0V to 2.2V. Circuits designed for the TLLY4401 must be verified for compatibility with lower forward voltage substitutes, particularly in current-limiting resistor calculations.

Q: Are all substitute parts available in the same package? A: Yes. All substitute parts use the T-1 radial through-hole package with diffused lens configuration, maintaining mechanical and electrical interface compatibility.

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