LTST-C195KGJRKT-5A Dual Color SMD LED Datasheet - Package Dimensions - Green/Red - 5V - 75mW - English Technical Document

1. Product Overview

The LTST-C195KGJRKT-5A is a dual-color, surface-mount device (SMD) LED utilizing advanced AlInGaP chip technology. This component is designed for applications requiring two distinct indicator colors from a single, compact package. It features an ultra-bright output and is housed in a standard EIA-compliant package, making it suitable for automated assembly processes including infrared and vapor phase reflow soldering. The device is compliant with RoHS directives and is classified as a green product.

1.1 Core Advantages

• Dual-Color Functionality: Integrates separate green and red LED chips within one package, saving board space and simplifying design for multi-state indication.
• High Brightness: The AlInGaP material delivers superior luminous intensity compared to traditional LED technologies.
• Manufacturing Compatibility: Packaged in 8mm tape on 7\" reels, it is fully compatible with high-speed automatic pick-and-place equipment.
• Robust Process Compatibility: Withstands standard infrared reflow soldering profiles, including those required for lead-free (Pb-free) assembly processes.

2. Technical Parameter Deep Dive

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operating the LED under conditions exceeding these values is not recommended.

• Power Dissipation (P_d): 75 mW per color (Green and Red). This is the maximum allowable power loss in the device.
• Peak Forward Current (I_FP): 80 mA. This is the maximum instantaneous forward current, typically specified under pulsed conditions (1/10 duty cycle, 0.1ms pulse width) to prevent overheating.
• Continuous Forward Current (I_F): 30 mA DC. The maximum steady-state current for reliable continuous operation.
• Current Derating: Linear derating of 0.4 mA/\u00b0C from 25\u00b0C. The maximum allowable forward current must be reduced as ambient temperature increases above 25\u00b0C.
• Reverse Voltage (V_R): 5 V. The maximum voltage that can be applied in the reverse direction across the LED.
• Operating Temperature Range (T_opr): -30\u00b0C to +85\u00b0C.
• Storage Temperature Range (T_stg): -40\u00b0C to +85\u00b0C.
• Soldering Temperature: Withstands 260\u00b0C for 5 seconds during infrared reflow.

2.2 Electrical and Optical Characteristics

These are the typical performance parameters measured at an ambient temperature (T_a) of 25\u00b0C and a test current (I_F) of 5mA, unless otherwise stated.

• Luminous Intensity (I_V):
  • Green: Minimum 4.5 mcd, Typical value not specified, Maximum 28.0 mcd.
  • Red: Minimum 7.1 mcd, Typical value not specified, Maximum 45.0 mcd.
  • Measurement is based on the CIE photopic eye-response curve.
• Viewing Angle (2\u03b8_1/2): 130 degrees (typical) for both colors. This is the full angle at which the luminous intensity drops to half of its peak axial value.
• Peak Wavelength (\u03bb_P):
  • Green: 574 nm (typical).
  • Red: 639 nm (typical).
• Dominant Wavelength (\u03bb_d):
  • Green: 571 nm (typical).
  • Red: 631 nm (typical).
  • This is the single wavelength perceived by the human eye, derived from the CIE chromaticity diagram.
• Spectral Bandwidth (\u0394\u03bb):
  • Green: 15 nm (typical).
  • Red: 20 nm (typical).
• Forward Voltage (V_F):
  • Typical: 1.9 V for both colors.
  • Maximum: 2.3 V for both colors at I_F = 5mA.
• Reverse Current (I_R): Maximum 10 \u00b5A for both colors at V_R = 5V.

3. Binning System Explanation

The LEDs are sorted (binned) according to their luminous intensity to ensure consistency within a production batch. The bin code is part of the part number (e.g., 'K' and 'J' in LTST-C195KGJRKT-5A).

3.1 Luminous Intensity Binning

Green Color (First letter after 'C195'):

• Bin J: 4.5 mcd (Min) to 7.1 mcd (Max)
• Bin K: 7.1 mcd to 11.2 mcd
• Bin L: 11.2 mcd to 18.0 mcd
• Bin M: 18.0 mcd to 28.0 mcd

Red Color (Second letter after 'C195'):

• Bin K: 7.1 mcd to 11.2 mcd
• Bin L: 11.2 mcd to 18.0 mcd
• Bin M: 18.0 mcd to 28.0 mcd
• Bin N: 28.0 mcd to 45.0 mcd

Tolerance on each intensity bin is \u00b115%. This specific part (GJ) uses Green Bin J and Red Bin K.

4. Performance Curve Analysis

The datasheet references typical characteristic curves which are essential for design. While the exact graphs are not reproduced in text, their implications are analyzed below.

4.1 Forward Current vs. Forward Voltage (I-V Curve)

The I-V characteristic is non-linear. For both the green and red chips, the typical forward voltage is 1.9V at 5mA. Designers must use this curve to select appropriate current-limiting resistors, as a small change in voltage can cause a large change in current. The maximum V_F of 2.3V should be used for worst-case power dissipation calculations.

4.2 Luminous Intensity vs. Forward Current

The light output is approximately proportional to the forward current within the recommended operating range. However, efficiency may drop at very high currents due to increased heat. The specified luminous intensity values are at 5mA; driving at the maximum continuous current of 30mA will yield significantly higher output but requires careful thermal management.

4.3 Temperature Characteristics

LED performance is temperature-dependent. The luminous intensity typically decreases as the junction temperature increases. The 0.4 mA/\u00b0C derating factor for forward current is a critical design parameter to prevent thermal runaway and ensure long-term reliability, especially in high ambient temperature environments.

5. Mechanical and Package Information

5.1 Package Dimensions and Pin Assignment

The device uses a standard SMD package. Key dimensional tolerances are \u00b10.10mm unless otherwise noted.

• Pin Assignment:
  • Green LED Chip: Connected to Pins 1 and 3.
  • Red LED Chip: Connected to Pins 2 and 4.
• Lens: Water Clear, allowing the true chip color (green and red) to be visible.

5.2 Recommended Soldering Pad Layout

A suggested land pattern (footprint) is provided to ensure reliable solder joint formation and proper alignment during reflow. Adhering to this pattern helps prevent tombstoning and ensures good thermal and electrical connection.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profiles

Two suggested infrared (IR) reflow profiles are provided: one for standard (SnPb) solder process and one for lead-free (SnAgCu) solder process. The lead-free profile requires a higher peak temperature (typically up to 260\u00b0C). It is crucial to follow the recommended time-temperature curve, including pre-heat, soak, reflow, and cooling zones, to prevent thermal shock to the LED package and ensure solder joint integrity.

6.2 Cleaning

If cleaning is necessary after soldering, only specified solvents should be used. Immersing the LED in ethyl alcohol or isopropyl alcohol at normal temperature for less than one minute is recommended. The use of unspecified chemicals can damage the plastic lens and package.

6.3 Storage Conditions

For extended reliability, LEDs should be stored in an environment not exceeding 30\u00b0C and 70% relative humidity. Components removed from their original moisture-barrier packaging should be reflow-soldered within one week. If storage beyond one week is necessary, they should be kept in a sealed container with desiccant or in a nitrogen atmosphere and baked (approximately 60\u00b0C for 24 hours) before assembly to remove absorbed moisture and prevent \"popcorning\" during reflow.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The device is supplied in standard embossed carrier tape wound on 7-inch (178mm) diameter reels.

• Packing Quantity: 4000 pieces per full reel.
• Minimum Order Quantity (MOQ): 500 pieces for remainder quantities.
• Tape Specifications: Compliant with ANSI/EIA-481-1-A-1994.
• Cover Tape: Empty component pockets are sealed with a top cover tape.
• Missing Components: A maximum of two consecutive missing LEDs (empty pockets) is allowed per reel specification.

8. Application Recommendations

8.1 Typical Application Scenarios

• Status Indicators: Ideal for equipment requiring dual-state indication (e.g., power on/standby, charge status, network activity/error) using green and red colors from a single component.
• Front Panel Displays: Used in consumer electronics, industrial controls, and automotive interiors where space is limited.
• Backlighting for Legends: Can be used to illuminate icons or symbols in different colors.

8.2 Circuit Design Considerations

Drive Method: LEDs are current-driven devices. To ensure uniform brightness when multiple LEDs are used in parallel, it is strongly recommended to use a separate current-limiting resistor in series with each LED (Circuit Model A). Driving multiple LEDs in parallel from a single resistor (Circuit Model B) is not recommended due to variations in the forward voltage (V_F) of individual LEDs, which can lead to significant differences in current and, consequently, brightness.

ESD Protection: AlInGaP LEDs are sensitive to electrostatic discharge (ESD). ESD damage can manifest as high reverse leakage current, low forward voltage, or failure to illuminate at low currents. Preventive measures must be implemented throughout handling and assembly:

• Use grounded wrist straps and anti-static mats.
• Ensure all equipment and workstations are properly grounded.
• Use ionizers to neutralize static charge on the LED lens.

9. Technical Comparison and Differentiation

The primary differentiation of this component lies in its dual-color capability within a single, standard SMD package. Compared to using two separate single-color LEDs, it offers significant space savings on the PCB, reduces component count, and simplifies the bill of materials (BOM). The use of AlInGaP technology provides higher luminous efficiency and better temperature stability than older technologies like GaAsP for the red chip, resulting in brighter and more consistent output. The wide 130-degree viewing angle makes it suitable for applications where visibility from off-axis angles is important.

10. Frequently Asked Questions (FAQ)

10.1 Can I drive both the green and red LEDs simultaneously?

Yes, but they must be driven independently through their respective pins (1/3 for green, 2/4 for red). Driving them simultaneously at their maximum current will exceed the total power dissipation rating for the package if not properly managed. Thermal calculations must consider the combined heat generated.

10.2 What is the difference between peak wavelength and dominant wavelength?

Peak wavelength (\u03bb_P) is the wavelength at which the spectral power distribution of the emitted light is maximum. Dominant wavelength (\u03bb_d) is the single wavelength that matches the perceived color of the light as defined by the CIE chromaticity diagram. For LEDs with a narrow spectrum, they are often close, but \u03bb_d is more relevant for color specification.

10.3 How do I interpret the bin code in the part number?

For LTST-C195GJRKT-5A, the letters \"GJ\" indicate the luminous intensity bin for the green and red chips, respectively. 'G' corresponds to the green chip's bin (which is 'J' in this case), and 'J' corresponds to the red chip's bin (which is 'K' in this case). Refer to Section 3.1 for the exact mcd ranges for bins J and K.

11. Design and Usage Case Study

Scenario: Dual-Status Power Indicator for a Portable Device. A compact handheld medical device requires a clear, space-efficient indicator for battery status: solid green for \"adequate charge,\" flashing green for \"charging,\" and solid red for \"low battery.\"

Implementation: The LTST-C195KGJRKT-5A is an ideal choice. A microcontroller GPIO pin drives the green LED (pins 1/3) through a 100\u03a9 current-limiting resistor (for ~20mA at ~3.3V supply, considering V_F~1.9V). Another GPIO pin drives the red LED (pins 2/4) through a similar resistor. The firmware controls the flashing and solid states. This design uses only one component footprint instead of two, simplifies routing, and provides a clean, professional appearance.

12. Technology Principle Introduction

The LED is based on Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor material. When a forward voltage is applied across the p-n junction, electrons and holes recombine, releasing energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy, which directly defines the wavelength (color) of the emitted light. The green chip uses a formulation for ~571nm emission, and the red chip uses a different formulation for ~631nm emission. The \"water clear\" lens is made of epoxy or silicone that is transparent to these wavelengths, allowing the true chip color to be seen without diffusion or color conversion.

13. Industry Trends and Developments

The trend in SMD indicator LEDs continues towards higher efficiency, smaller package sizes, and increased functionality. Dual- and multi-color LEDs in single packages are becoming more common to meet demands for miniaturization and richer user interfaces. There is also a focus on improving reliability under harsh conditions, such as higher temperature reflow profiles required for lead-free soldering and resistance to moisture and chemicals. Furthermore, the integration of current-limiting resistors or even driver ICs within the LED package (\"smart LEDs\") is an emerging trend to further simplify circuit design and improve performance consistency.