LTC-5753JD-01 LED Display Datasheet - 0.56-inch Digit Height - Hyper Red (650nm) - 2.6V Forward Voltage - 70mW Power Dissipation - English Technical Document

1. Product Overview

The LTC-5753JD-01 is a high-performance, quadruple-digit, seven-segment alphanumeric display module designed for applications requiring clear, bright numeric readouts. Its primary function is to visually represent numerical data across four distinct digits, each composed of seven individually addressable LED segments plus a decimal point. The device is engineered for integration into instrumentation panels, industrial control systems, test equipment, consumer electronics, and any interface where reliable, multi-digit numeric display is essential.

The core advantage of this display lies in its use of AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor technology for the Hyper Red LED chips. This material system is renowned for its high efficiency and excellent luminous intensity in the red-orange spectrum. The display features a light gray face with white segments, which significantly enhances contrast and readability under various lighting conditions, contributing to its "excellent character appearance." The device is categorized for luminous intensity, ensuring consistent brightness levels across production batches for uniform visual performance in multi-unit installations.

2. Technical Specifications Deep Dive

This section provides a detailed, objective analysis of the key technical parameters defined in the datasheet, explaining their significance for design and application.

2.1 Photometric and Optical Characteristics

The optical performance is central to the display's functionality. The key parameters are measured under standardized test conditions (typically Ta=25°C).

• Average Luminous Intensity (I_V): Ranges from a minimum of 200 µcd to a typical value of 650 µcd at a forward current (I_F) of 1mA. This parameter quantifies the perceived brightness of the lit segment by the human eye, using a filter that approximates the CIE photopic response curve. The high typical value ensures good visibility.
• Peak Emission Wavelength (λ_p): 650 nanometers (nm). This is the wavelength at which the optical power output of the LED is at its maximum. It defines the "Hyper Red" color characteristic.
• Dominant Wavelength (λ_d): 639 nm. This is the single wavelength that best matches the perceived color of the LED light to the human eye. The difference between peak and dominant wavelength is typical for LEDs due to the shape of the emission spectrum.
• Spectral Line Half-Width (Δλ): 20 nm. This specifies the bandwidth of the emitted light, measured as the full width at half maximum (FWHM) of the spectral power distribution. A value of 20 nm indicates a relatively pure, saturated red color.
• Luminous Intensity Matching Ratio (I_V-m): 2:1 maximum. This is a critical parameter for display uniformity. It specifies that the luminous intensity of any one segment shall not be more than twice that of any other segment within the same device when driven under identical conditions (I_F=1mA). This ensures balanced brightness across all segments of a digit.

2.2 Electrical and Thermal Characteristics

These parameters define the electrical operating limits and conditions for reliable and safe use.

• Forward Voltage per Segment (V_F): Typically 2.6V, with a maximum of 2.6V at I_F=20mA. This is the voltage drop across an LED segment when it is conducting current. It is crucial for designing the current-limiting circuitry in the driver stage.
• Continuous Forward Current per Segment (I_F): 25 mA maximum at 25°C. This is the maximum DC current that can be continuously applied to a single segment without risking degradation. The datasheet specifies a derating factor of 0.33 mA/°C above 25°C, meaning the maximum allowable current decreases as ambient temperature increases to manage junction temperature.
• Peak Forward Current per Segment: 90 mA maximum. This is allowed only under pulsed conditions with a 1/10 duty cycle and a 0.1ms pulse width. This enables multiplexing schemes where higher instantaneous current is used to achieve perceived brightness while keeping average power dissipation within limits.
• Reverse Voltage per Segment (V_R): 5 V maximum. Applying a reverse bias voltage higher than this can cause immediate and catastrophic failure of the LED junction.
• Reverse Current per Segment (I_R): 100 µA maximum at V_R=5V. This is the small leakage current that flows when the LED is reverse-biased within its maximum rating.
• Power Dissipation per Segment (P_D): 70 mW maximum. This is the maximum power that can be dissipated as heat in a single segment. Exceeding this limit, primarily determined by I_F * V_F, can lead to overheating and reduced lifespan.

2.3 Absolute Maximum Ratings and Environmental Limits

These are stress limits that must not be exceeded under any circumstances, even momentarily. Operation beyond these ratings may cause permanent damage.

• Operating Temperature Range: -35°C to +85°C. The device is guaranteed to function within this ambient temperature range, though electrical parameters like forward current may need derating at high temperatures.
• Storage Temperature Range: -35°C to +85°C. The device can be stored without operation within this range.
• Solder Temperature: Maximum 260°C for a maximum of 3 seconds, measured 1.6mm (1/16 inch) below the seating plane. This is critical for wave soldering or reflow processes to prevent thermal damage to the LED chips or package.

3. Binning and Categorization System

The datasheet explicitly states that the device is "categorized for luminous intensity." This indicates a production binning process. While specific bin codes are not provided in this excerpt, typical categorization for such displays involves grouping units based on measured luminous intensity at a standard test current (e.g., I_F=1mA). This ensures that designers sourcing multiple displays for a single product can achieve uniform brightness across all units, which is vital for professional-looking end products. It is implied that other key parameters like forward voltage and dominant wavelength are also controlled within specified tolerances to guarantee consistent performance.

4. Performance Curve Analysis

The datasheet references "Typical Electrical / Optical Characteristic Curves." While the specific graphs are not detailed in the provided text, standard curves for such devices typically include:

• Relative Luminous Intensity vs. Forward Current (I_V vs. I_F): Shows how brightness increases with current, usually in a sub-linear fashion at higher currents due to heating and efficiency droop.
• Forward Voltage vs. Forward Current (V_F vs. I_F): Demonstrates the diode's exponential I-V characteristic, crucial for designing constant-current drivers.
• Relative Luminous Intensity vs. Ambient Temperature (I_V vs. T_a): Illustrates how LED output decreases as junction temperature rises, highlighting the importance of thermal management.
• Spectral Power Distribution: A graph showing the intensity of light emitted across the wavelength spectrum, centered around the 650nm peak.

These curves allow designers to predict performance under non-standard operating conditions and optimize their driver circuits for efficiency and longevity.

5. Mechanical and Packaging Information

5.1 Physical Dimensions and Outline

The package drawing is referenced. Key features of a standard 4-digit, 0.56-inch display include an overall module size that houses four side-by-side digits, a pin spacing compatible with standard DIP (Dual In-line Package) sockets or PCB footprints, and a segment height of 14.2 mm. The "continuous uniform segments" feature suggests a seamless appearance between digits, often achieved with a single, molded faceplate. Tolerances on dimensions are typically ±0.25 mm unless otherwise specified.

5.2 Pin Connection and Circuit Diagram

The device has a 12-pin configuration. It utilizes a Common Cathode multiplexing architecture. This means the cathode (negative side) of all LEDs for a specific digit are connected together internally, while the anodes (positive side) for each segment type (A-G, DP) are shared across all digits.

• Pins 6, 8, 9, 12: These are the common cathode pins for Digit 4, Digit 3, Digit 2, and Digit 1, respectively.
• Pins 1, 2, 3, 4, 5, 7, 10, 11: These are the anode pins for segments E, D, DP, C, G, B, F, and A, respectively.

The internal circuit diagram would show four sets of seven LEDs (plus DP) arranged with their anodes tied to the segment lines and their cathodes tied to the respective digit lines. This structure is fundamental to the multiplexing drive technique.

6. Soldering and Assembly Guidelines

Adherence to the specified soldering profile is non-negotiable for reliability. The absolute maximum rating for solder temperature is 260°C for 3 seconds. In practice, a lead-free reflow profile with a peak temperature slightly below this maximum (e.g., 250°C) is recommended to provide a safety margin. The measurement point (1.6mm below seating plane) is critical as it represents the temperature at the package leads, not necessarily the hot air temperature in the reflow oven. Prolonged exposure to high temperature can damage the internal wire bonds, degrade the LED epoxy, or cause delamination. Manual soldering with an iron should be performed quickly and with adequate thermal relief on the PCB pad. Proper ESD (Electrostatic Discharge) handling procedures should always be followed during assembly.

7. Application Suggestions

7.1 Typical Application Circuits

The LTC-5753JD-01 is designed for multiplexed (multiplex) operation. A typical driver circuit involves a microcontroller or dedicated display driver IC (e.g., MAX7219, TM1637). The driver sequentially activates (sinks current to ground) one digit cathode at a time while applying the correct pattern of segment anode voltages (through current-limiting resistors) for that digit. This cycle repeats at a high frequency (typically >100Hz), exploiting persistence of vision to make all four digits appear continuously lit. This method drastically reduces the required number of driver pins from 36 (4 digits * 9 segments) to just 12 (8 segments + 4 digits).

7.2 Design Considerations and Best Practices

• Current Limiting Resistors: Essential for each segment anode line. The resistor value is calculated based on the supply voltage (V_CC), the LED forward voltage (V_F), and the desired segment current (I_F). Formula: R = (V_CC - V_F) / I_F. For multiplexing, I_F is the peak current, not the average.
• Multiplexing Frequency and Duty Cycle: A frequency high enough to avoid visible flicker (usually >60-100 Hz) is required. The duty cycle for each digit in a 4-digit multiplex is 1/4 (25%). To achieve the same perceived brightness as a statically driven LED at current I, the peak current during its active time slot must be approximately 4I. This must be checked against the peak current rating (90mA).
• Power Supply Decoupling: Place a 0.1µF ceramic capacitor close to the display module's power pins to smooth out the pulsed current demands of multiplexing.
• Viewing Angle: The "wide viewing angle" feature is beneficial for applications where the display may be viewed from off-axis positions. PCB mounting should consider the intended user's sightlines.

8. Technical Comparison and Differentiation

Compared to older technologies like standard GaAsP or GaP red LEDs, the AlInGaP Hyper Red LED offers significantly higher luminous efficiency, resulting in greater brightness for the same drive current or lower power consumption for the same brightness. The 650nm wavelength provides a vibrant, deep red color. Compared to common anode configurations, the common cathode configuration is often more convenient to interface with modern microcontrollers, which are better at sinking current (to ground) than sourcing it. The 0.56-inch digit height places it in a category suitable for medium-distance viewing, larger than miniature SMD displays but smaller than large panel-mounted units.

9. Frequently Asked Questions (FAQ)

Q: Can I drive this display with a constant DC voltage without multiplexing?
A: Technically yes, but it is highly inefficient and requires a large number of I/O pins (one per segment per digit). Multiplexing is the intended and optimal method of operation.

Q: Why is the peak current rating so much higher than the continuous current rating?
A: This is due to thermal limits. During a short pulse, the LED junction does not have time to heat up significantly, allowing a higher instantaneous current without exceeding the maximum junction temperature. This property is exploited in multiplexing.

Q: What is the purpose of the luminous intensity matching ratio?
A: It guarantees visual uniformity. Without this specification, one segment (e.g., segment A) might be noticeably brighter or dimmer than another (e.g., segment D) in the same digit, creating an uneven, unprofessional appearance.

Q: How do I calculate the average power consumption?
A: For a multiplexed display, calculate the power for one segment when lit (I_{F_peak} * V_F), multiply by the number of segments lit in a typical digit (e.g., 7 for an "8"), then multiply by the duty cycle (1/4 for 4-digit mux). This gives the average power for one digit. Multiply by 4 for total module power. Remember to include the driver IC's own consumption.

10. Operational Principle

The device operates on the principle of electroluminescence in a semiconductor p-n junction. When a forward bias voltage exceeding the diode's turn-on voltage (approximately 2.1-2.6V) is applied across an AlInGaP LED segment, electrons and holes are injected into the active region where they recombine. This recombination process releases energy in the form of photons (light) with a wavelength characteristic of the AlInGaP material bandgap, which is in the hyper red region (~650nm). The internal circuit is arranged in a matrix (common cathode per digit, common anodes per segment type) to enable time-division multiplexing, where only one digit is electrically active at any instant, but all appear lit due to rapid sequential scanning.

11. Industry Context and Trends

Displays like the LTC-5753JD-01 represent a mature and reliable technology. While newer display technologies like OLEDs and high-resolution dot-matrix LCDs offer more flexibility for graphics and custom fonts, seven-segment LED displays remain dominant in applications prioritizing extreme reliability, high brightness, wide viewing angles, low cost, and simplicity—especially in industrial, automotive, and outdoor environments. The trend within this segment is towards higher efficiency (more lumens per watt), allowing for lower power consumption and reduced heat generation, and towards surface-mount device (SMD) packages for automated assembly, though through-hole packages like this one remain popular for prototyping, repair, and certain ruggedized applications. The use of advanced semiconductor materials like AlInGaP over older GaAsP is a direct result of this efficiency-driven trend.