LTST-C191YKT Yellow 0603 SMD LED Equivalent & Substitute Parts

Part Overview

The LTST-C191YKT is a yellow 588nm surface mount LED in 0603 (1608 Metric) package manufactured by Lite-On Inc. This part is classified as obsolete. Due to its discontinued status, equivalent and substitute parts from active product lines are necessary for ongoing design support and procurement continuity. Substitute parts maintain compatibility through matching mechanical form factor, electrical characteristics, and optical performance within acceptable tolerances.

Key Parameters

Parameter	Value
Manufacturer Part Number	LTST-C191YKT
Manufacturer	Lite-On Inc.
Product Status	Obsolete
Package / Case	0603 (1608 Metric)
Color	Yellow
Wavelength - Dominant	588nm
Voltage - Forward (Vf) (Typ)	2.1V
Current - Test	20mA
Millicandela Rating	4.5mcd
Viewing Angle	130°
Mounting Type	Surface Mount
Size / Dimension	1.60mm L x 0.80mm W
Height (Max)	0.55mm
Lens Style	Rectangle with Flat Top
Lens Transparency	Clear

Substitute Part Grouping Explanation

Substitution logic is based on the following critical parameters that determine functional and mechanical compatibility:

Primary Compatibility Criteria:

Package / Case: 0603 (1608 Metric) — mechanical fit and PCB assembly compatibility
Color: Yellow — optical output specification
Mounting Type: Surface Mount — assembly process compatibility
Voltage - Forward (Vf): 2.0V to 2.1V — circuit design tolerance
Current - Test: 20mA — standard test condition alignment
Wavelength - Dominant: 585nm to 595nm — color perception and application tolerance

Substitute parts are grouped into two categories:

Category A — Direct Yellow LED Substitutes (Dominant Wavelength 585–595nm): Parts that maintain yellow color specification with forward voltage and test current matching the original part. These include LTST-C190YKT, LTST-C191KSKT, 150060YS75000, 5988040102F, 5988040107F, 5988050102F, 5988050107F, and SM0603UYC.

Category B — Alternative Color (Orange, 605nm): Part 5988030102F and 5988030107F are orange LEDs (605nm dominant wavelength). These are listed as substitutes only where color shift from yellow to orange is acceptable in the application.

Parameter Comparison

Part Number	Manufacturer	Product Status	Color	Wavelength - Dominant (nm)	Vf (Typ) (V)	Current - Test (mA)	Millicandela (mcd)	Viewing Angle (°)	Height Max (mm)	Package
LTST-C191YKT	Lite-On Inc.	Obsolete	Yellow	588	2.1	20	4.5	130	0.55	0603
LTST-C190YKT	Lite-On Inc.	Active	Yellow	588	2.1	10	6	130	0.90	0603
LTST-C191KSKT	Lite-On Inc.	Active	Yellow	591	2.1	20	104	130	0.65	0603
150060YS75000	Würth Elektronik	Active	Yellow	590	2.0	20	120	140	0.80	0603
5988040102F	Dialight	Active	Yellow	593	2.0	20	130	140	0.70	0603
5988040107F	Dialight	Active	Yellow	593	2.0	20	140	140	0.70	0603
5988050102F	Dialight	Active	Yellow	587	2.0	20	130	140	0.70	0603
5988050107F	Dialight	Active	Yellow	587	2.0	20	140	140	0.70	0603
SM0603UYC	Bivar Inc.	Active	Yellow	592	2.1	20	70	130	0.60	0603
5988030102F	Dialight	Active	Orange	605	2.0	20	80	140	0.70	0603
5988030107F	Dialight	Active	Orange	605	2.0	20	120	140	0.70	0603

Engineering Selection Recommendations

Primary Substitutes (Yellow Color Match, Active Status):

LTST-C191KSKT is the manufacturer-recommended primary substitute from Lite-On Inc. It maintains identical forward voltage (2.1V), test current (20mA), wavelength specification (591nm, within yellow range), and viewing angle (130°). Product status is active with RoHS3 compliance. This part offers the closest electrical and optical alignment with the obsolete LTST-C191YKT.

5988040107F and 5988050107F from Dialight are active alternatives with yellow wavelengths (593nm and 587nm respectively) and identical test current (20mA). Forward voltage is 2.0V, which is within acceptable tolerance for 2.1V-rated circuits. Both parts feature higher brightness (140mcd) and wider viewing angle (140°) compared to the original 4.5mcd specification. RoHS3 compliance is confirmed.

150060YS75000 from Würth Elektronik (WL-SMCW series) is an active yellow LED with 590nm wavelength, 2.0V forward voltage, and 20mA test current. Brightness is 120mcd with 140° viewing angle. RoHS3 compliant.

SM0603UYC from Bivar Inc. maintains 2.1V forward voltage and 20mA test current with 592nm wavelength. Brightness is 70mcd at 130° viewing angle. RoHS3 compliant and active status.

LTST-C190YKT from Lite-On Inc. is active but operates at 10mA test current (half the original specification) and has lower brightness (6mcd). Use only where reduced brightness is acceptable.

Alternative Substitute (Orange Color, Active Status):

5988030102F and 5988030107F are orange LEDs (605nm) from Dialight. These are substitutes only where application requirements permit color shift from yellow to orange. Both are active, RoHS3 compliant, with 2.0V forward voltage and 20mA test current.

Compliance and Regulatory Status:

All recommended substitutes are RoHS3 compliant and REACH unaffected. All parts maintain 0603 (1608 Metric) package compatibility and surface mount assembly compatibility.

Frequently Asked Questions (FAQ)

Q: Can LTST-C191KSKT directly replace LTST-C191YKT in existing designs?

A: Yes. LTST-C191KSKT maintains identical forward voltage (2.1V), test current (20mA), and viewing angle (130°). Wavelength is 591nm versus 588nm in the original, both within the yellow color specification range. Height is 0.65mm versus 0.55mm; verify PCB clearance in height-constrained applications.

Q: What is the difference between Dialight 5988040107F and 5988050107F?

A: Both are yellow 0603 LEDs with identical electrical specifications (2.0V, 20mA, 140mcd, 140° viewing angle). The primary difference is dominant wavelength: 5988040107F is 593nm while 5988050107F is 587nm. Both are within acceptable yellow color range. Selection depends on specific color tone requirements.

Q: Can I use orange LEDs (5988030102F or 5988030107F) as substitutes?

A: Orange LEDs are substitutes only if the application permits color shift from yellow (588nm) to orange (605nm). Electrical specifications match (2.0V, 20mA, 0603 package), but optical output color will differ. Verify application requirements before substitution.

Q: What is the impact of forward voltage difference between 2.1V and 2.0V?

A: Forward voltage tolerance of ±0.1V is standard in LED circuit design. Parts rated 2.0V are compatible with 2.1V-rated circuits. Verify series resistor values in current-limiting circuits to ensure proper brightness and operating point.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All recommended substitute parts are RoHS3 compliant and REACH unaffected, matching the regulatory status of the original LTST-C191YKT.

Q: Does package height affect PCB assembly?

A: Yes. Original LTST-C191YKT height is 0.55mm maximum. Substitute parts range from 0.60mm to 0.90mm. Verify PCB clearance, solder reflow profile compatibility, and component placement constraints before substitution.

Q: What is the brightness difference between the original and substitutes?

A: Original LTST-C191YKT is 4.5mcd at 20mA test current. Most substitutes are significantly brighter (70–140mcd). If brightness reduction is required, LTST-C190YKT (6mcd at 10mA) is the closest match, though it operates at half the test current.

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