LTP-181FFM LED Dot Matrix Display Specification Sheet - 1.86 Inch (47.4mm) Height - Green and Super Bright Red - 16x16 Dot Matrix - Simplified Chinese Technical Documentation

1. Product Overview

LTP-181FFM, net bir şekilde alfasayısal veya sembol bilgisi görüntülemesi gereken uygulamalar için tasarlanmış orta boyutlu, iki renkli bir nokta matrisi görüntüleme modülüdür. Temel işlevi, ızgara düzeninde düzenlenmiş, ayrı ayrı adreslenebilir ışık yayan diyotlardan (LED) oluşan bir görsel çıktı arayüzü sağlamaktır.

1.1 Core Advantages and Target Market

This device is designed with several key advantages, making it suitable for industrial, commercial, and instrumentation applications. It features1.86-inch (47.4 mm) character height, ensuring excellent readability over long distances. The display provideshigh brightness and high contrast, ensuring visibility even in well-lit environments. Itswide viewing angleAllows clear viewing of information from different positions on the display surface.

From a reliability perspective, it possesses the inherentsolid-state reliability, meaning no moving parts and a long service life. ItsLow power consumption requirement, very energy efficient. An important mechanical feature is that the modules can beVertically and horizontally stacked, enabling the creation of larger display panels or multi-line displays without complex interfaces. The LEDs also undergoluminous intensity binning, ensuring brightness consistency between different units and within the dot matrix, which is crucial for uniform appearance.

The target market includes public information displays, industrial control panels, test and measurement equipment, traffic signs, and any system requiring rugged, reliable, and clear status or data display.

2. Detailed Technical Specifications

The LTP-181FFM is a 16-row by 16-column dot matrix display. It utilizes two different LED semiconductor technologies to achieve dual-color display capability.

2.1 Device Description and Technology

The green LED chip employsGaP material on a gallium phosphide (GaP) substrateThese ratings define the limits beyond which permanent damage to the device may occur. They are specified at an ambient temperature (TAluminum Indium Gallium Phosphide (AlInGaP)technology, specifically labeled as "Ultrabright Red," indicating high efficiency and purity in the red spectrum. These red chips are grown onOpaque Gallium Arsenide (GaAs) substrateOn. The display usesBlack panelBy absorbing ambient light to enhance contrast, and adding aDiffusion film, fuses individual light points into a more uniform character appearance, reducing the "dot-like" visual effect.

2.2 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. They are specified at an ambient temperature (T_A) of 25°C.

• Average power dissipation per point:Green: 36 mW, Super Bright Red: 40 mW.
• Peak forward current per point:Green: 100 mA, Super Bright Red: 90 mA.
• Average forward current per point:Green: 13 mA, super bright red: 15 mA. This rating must be linearly derated above 25°C, with a derating rate of 0.17 mA/°C for green and 0.2 mA/°C for red.
• Reverse voltage per point:Both colors are 5 V.
• Operating and Storage Temperature Range:-35°C to +85°C.
• Soldering Temperature:260°C ake 3 sekunde, wuraren bincike yana ƙarƙashin filin shigar da kayan aiki 1/16 inci (≈1.59 mm).

2.3 Electrical and Optical Characteristics

Waɗannan sune a cikin T_A= 25°C ƙayyadaddun sharuɗɗan gwaji waɗanda aka tabbatar da su.

2.3.1 Green LED Characteristics

• Average luminous intensity (I_V):Typical value 1400 µcd, minimum value 500 µcd. Test condition: peak current (I_p) = 35 mA, duty cycle 1/16.
• Peak emission wavelength (λ_p):565 nm (typical). Test conditions: forward current (I_F) = 20 mA.
• Spectral line half-width (Δλ):30 nm (typical value). I_F= 20 mA.
• Dominant wavelength (λ_d):569 nm (typical value). I_F= 20 mA.
• Forward voltage per point (V_F):At I_F=80mA, typical value 2.6 V (maximum 3.7 V); at I_F=20mA, typical value 2.1 V.
• Reverse current per point (I_R):In V_R= 5V, maximum 100 µA.
• Luminous intensity matching ratio (I_V-m):The maximum ratio between any two points is 1.6:1. Test conditions: I_p= 35 mA, duty cycle 1/16.

2.3.2 AlInGaP Ultra-Bright Red LED Characteristics

• Average luminous intensity (I_V):Typical value 1500 µcd, minimum value 500 µcd. Test conditions: I_p= 15 mA, duty cycle 1/16.
• Peak emission wavelength (λ_p):650 nm (typical). I_F= 20 mA.
• Spectral line half-width (Δλ):35 nm (typical). I_F= 20 mA.
• Dominant wavelength (λ_d):639 nm (typical). I_F= 20 mA.
• Forward voltage per point (V_F):At I_F=80mA, typical 2.8 V (implied maximum 3.7 V); at I_FAt =20mA, typical value is 2.6 V.
• Reverse current per point (I_R):In V_R= 5V, maximum 100 µA.
• Luminous intensity matching ratio (I_V-m):Maximum 1.6:1. Test condition: I_p= 15 mA, duty cycle 1/16.

Note: Luminous intensity measurement uses a sensor and filter approximating the CIE photopic response curve.

3. Binning System Description

The datasheet indicates that the LED undergoesluminous intensity binning. This is a critical grading process.

• Luminous Intensity Grading:The specified maximum matching ratio of 1.6:1 ensures that under identical driving conditions within a single display module, no individual LED point is more than 60% brighter than the dimmest point. This is crucial for achieving uniform brightness of characters and the entire display area, preventing the appearance of "hot spots" or dim segments.
• Wavelength:While typical values for peak wavelength (565nm, 650nm) and dominant wavelength (569nm, 639nm) are provided, production variations are controlled to ensure the green and red colors fall within acceptable visual bands. The spectral half-width data (30nm, 35nm) indicates color purity.
• Forward Voltage:The specified range (e.g., 2.1V to 3.7V for green at high current) accounts for natural variations in semiconductor manufacturing. The drive circuit must be designed to accommodate this range to ensure uniform brightness.

4. Performance Curve Analysis

The datasheet referencesTypical Electrical/Optical Characteristic Curves. Although the provided text does not detail specific charts, the standard curves for such devices typically include:

• I-V (Current-Voltage) curve:It shows the relationship between the forward current and forward voltage of a single LED point. It is nonlinear, with a turn-on/threshold voltage (approximately 1.8-2.0V for these colors), after which the current increases rapidly with a small increase in voltage. This curve is crucial for designing current-limiting circuits.
• Luminous Intensity vs. Forward Current (I_F):It shows how the light output increases with current. It is typically linear over a wide range but saturates at very high currents due to thermal effects.
• Luminous Intensity vs. Ambient Temperature:Shows how light output decreases as the LED junction temperature increases. This derating is directly related to the average current derating specified in the absolute maximum ratings.
• Spectral Distribution:A plot of relative intensity versus wavelength, showing the peak wavelength and dominant wavelength along with the spectral half-width, confirming color characteristics.

5. Mechanical and Packaging Information

5.1 Package Dimensions

The datasheet contains detailed mechanical drawings (not shown here). Key notes in the drawings indicateAll dimensions are in millimeters (mm)., andDefault tolerance is ±0.25 mm (0.01 in).Unless otherwise specified by particular feature annotations. This drawing defines the overall outline dimensions, mounting hole locations, the visible area of the LED dot matrix, and the precise positions and spacing of the 48 pins.

5.2 Pin Connections and Circuit Diagram

This device uses a 48-pin dual in-line package. Due to the adoption of a multiplexed 16x16 dot matrix, the pin definitions are relatively complex. The pins are designated asRow Common Anode或Column Cathode, and has dedicated pins for green and red LEDs. For example, Pin 3 is the Green Column 1 Cathode, while Pin 11 is the Red Column 1 Cathode. This arrangement allows the controller to select a row (by applying a positive voltage to its common anode) and then sink current through the corresponding column cathode pin to illuminate specific green or red dots in that row.

The datasheet references an internal schematic, which typically shows the interconnections of all 256 LEDs (16x16), clarifying which anode row and cathode column control each specific LED dot for each color.

6. Soldering and Assembly Guide

The primary guidance provided isSoldering Temperature Profile: Maintain at 260°C for 3 seconds, with the measurement point located 1/16 inch (1.59 mm) below the package body. This is the standard reference point for wave soldering or hand soldering to prevent overheating damage to the internal LED or plastic package. For reflow soldering, a standard lead-free profile with a peak temperature of approximately 260°C is applicable, but the Time Above Liquidus (TAL) should be controlled to meet the 3-second guideline at the pin level.

Operation should follow standard ESD (Electrostatic Discharge) precautions for semiconductor devices. Storage should be within the specified temperature range of -35°C to +85°C and in a low-humidity environment.

7. Application Recommendations

7.1 Typical Application Scenarios

• Industrial Control Panel:Display machine status, production count, error codes, or setpoints.
• Test and measurement equipment:Display numerical readings, units, and mode indicators.
• Information display:Used in public places to display simple messages, queue numbers, or transportation schedules.
• Stacked Display System:Multiple modules can be combined to display longer text information, larger fonts, or multiple lines of data.

7.2 Design Considerations

• Drive Circuit:A microcontroller with sufficient I/O pins or a dedicated LED display driver IC (such as MAX7219 or similar multiplexing drivers) is required to manage 16:1 multiplexing (16 rows). The driver must provide the peak current required for the selected points (e.g., 80mA per point, divided by the duty cycle).
• Current Limiting:An external current-limiting resistor or constant-current driver must be used for each cathode column (or its grouping) to prevent exceeding the absolute maximum current and to set the desired brightness. Calculations must use the maximum V_Fto ensure safe current under all conditions.
• Thermal Management:The derating specification for average current with temperature must be adhered to. At high ambient temperatures, it may be necessary to reduce the multiplexing duty cycle or peak current to keep the junction temperature within safe limits and maintain brightness uniformity.
• Viewing Angle:A wide viewing angle is beneficial, but it should be considered during mechanical housing design to align with the intended observer position.

8. Technical Comparison and Differentiation

Compared to generic monochrome or smaller dot-matrix displays, the LTP-181FFM offers distinct advantages:

• Dual-color capability:Using dedicated green and high-efficiency AlInGaP ultra-bright red LEDs, it enables dual-color information display (e.g., green for normal status, red for alarm/warning), enhancing information density and clarity.
• Large character height (1.86 inches):Compared to smaller 5x7 or 8x8 dot matrices, it provides excellent long-distance readability, bridging the gap between small indicator lights and large signage.
• Intensity Binning:The guaranteed 1.6:1 intensity matching ratio is a mark of quality, ensuring professional-grade display uniformity, which cheap, un-binned displays may lack.
• Stackable Design:Mechanical design facilitates easy assembly of multi-module displays, a feature not commonly found in displays designed for standalone use.

9. Frequently Asked Questions (Based on Technical Parameters)

Q1: What is the difference between "peak" wavelength and "dominant" wavelength?
A: Peak wavelength (λ_p) is the wavelength at which the emitted light intensity reaches its maximum. Dominant wavelength (λ_d) is the wavelength of monochromatic light that matches the perceived color of the LED. For LEDs, λ_dis typically more relevant to human color perception.

Q2: Why are the test currents for luminous intensity different for green (35mA) and red (15mA)?
A: This reflects the different efficiencies of the two semiconductor technologies. The AlInGaP ultra-bright red LED is more efficient, achieving its typical luminous intensity (1500 µcd) at a lower drive current than the GaP green LED requires to reach its typical intensity (1400 µcd).

Q3: How to calculate the required series resistor for a column?
A: Using Ohm's Law: R = (V_{Power Supply}- V_F- V_{Drive Tube Voltage Drop}) / I_F. Use the maximum V from the datasheet_F(e.g., green is 3.7V at 80mA) to ensure that even for low V_FLEDs, the current never exceeds the limit. Consider the voltage drop (V_{Drive Tube Voltage Drop}) of the column drive transistor/MOSFET. Current I_FIt is the required peak current per point (e.g., 80mA), but please remember that in a multiplexed design, this current is shared by all points in the columns that are active within the single row's time slot.

Q4: What does "1/16 DUTY" in the test conditions mean?
A: It indicates that the display is driven in a multiplex mode with a 1/16 duty cycle. This is standard for a 16-row dot matrix. Each row is powered on for only 1/16 of the total refresh cycle time. The luminous intensity is measured under this condition, which is also how the display operates in actual use. The peak current during the "on" time is higher than the average current to compensate for the low duty cycle and achieve the desired average brightness.

10. Design Use Case Studies

Scenario: Design a multi-line production counter display.
An engineer needs to design a display for the factory floor to show the current production count and target value of a machine. They choose to vertically stack two LTP-181FFM modules.

Implementation Plan:A single microcontroller drives two display modules. The firmware manages a 16-line multiplexing routine, refreshing each line sequentially. The top module displays "COUNT: [number]" in green. The bottom module displays "TARGET: [number]" in green. If the machine stops due to an error, the relevant line or a separate "ERROR" message can flash in red on the corresponding module. The stackable design simplifies mechanical installation. High brightness and a wide viewing angle ensure operators can see the information from various positions in the workshop. Intensity grading ensures a consistent, uniform appearance when two modules are placed side-by-side.

11. Introduction to Working Principles

LTP-181FFM is based onLED dot matrix multiplexingPrinciple of operation. It is impractical to equip a 16x16 monochrome or bicolor dot matrix with 256 or more independent leads. Instead, LEDs are arranged in a grid where the anodes of all LEDs in a single row are connected together (row common anode), and the cathodes of all LEDs of a specific color in a single column are connected together (column cathode).

To illuminate a specific point (e.g., the green point at row 5, column 3), the controller performs the following steps in rapid succession within a refresh cycle: 1) Set the common anode of row 5 to a positive voltage (e.g., +5V). 2) Connect the cathode of column 3 (green) to ground (0V), completing the circuit and allowing current to flow through that specific green LED. All other rows are turned off, and all other column lines are held high (open circuit). By scanning all 16 rows very quickly (e.g., 100Hz or higher), the persistence of vision creates the illusion that all desired points in the 16x16 dot matrix are lit simultaneously. Bicolor capability simply adds an independent set of cathode pins for the red LEDs, which are controlled independently.

12. Technical Trends

LTP-181FFM olgun GaP (yeşil) ve AlInGaP (kırmızı) teknolojilerini kullanırken, daha geniş LED ekran alanı gelişmektedir. Trendler şunları içerir:

• Daha yüksek verimli malzemeler:Kugeuza kutoka AlInGaP kwenye GaAs hadi miundo yenye ufanisi zaidi, au kutumia vifaa vya LED nyekundu vinavyotegemea InGaN (ingawa ni changamoto), ili kuboresha ufanisi na anuwai ya rangi.
• Viendeshi vilivyojumuishwa:Moduli mpya za kuonyesha kwa kawaida hujumuisha IC ya kiendeshi cha kuzidisha, na wakati mwingine hata kiolesura cha kidhibiti kidogo (kama vile I2C au SPI) moja kwa moja kwenye PCB ya moduli, ikilinganishwa na safu wazi ya LED kama LTP-181FFM, hurahisisha kwa kiasi kikubwa muundo wa mzunguko wa nje.
• Surface Mount Technology (SMT):Many modern LED dot matrix displays use SMT LEDs and packages, allowing for thinner profiles, automated assembly, and potentially higher resolution. The through-hole design of the LTP-181FFM is robust and suitable for applications where manual soldering or repair might occur.
• Full-color RGB dot matrix:For more advanced graphics or multi-color text applications, dot matrices that integrate red, green, and blue (RGB) LEDs per pixel are becoming increasingly common, although they require more complex driving electronics.

The LTP-181FFM represents a reliable, high-performance solution in its category, balancing size, brightness, dual-color capability, and design flexibility for a wide range of embedded display applications.