LTC-5837JD LED Display Datasheet - 0.52-inch Digit Height - Hyper Red 650nm - 2.6V Forward Voltage - English Technical Document

1. Product Overview

The LTC-5837JD is a high-performance, quadruple-digit, seven-segment LED display module. Its primary function is to provide clear, bright numeric and limited alphanumeric information in a wide range of electronic equipment. The device is built using advanced AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor technology for the LED chips, which are mounted on a non-transparent GaAs substrate. This construction yields a display with a gray face and white segments, offering excellent contrast for readability. The display features a common anode configuration, which is a standard design choice for simplifying multiplexing drive circuits in multi-digit applications.

1.1 Core Advantages and Target Market

The display is designed for applications requiring reliable, high-visibility numeric readouts. Its core advantages, as listed in the datasheet, include a continuous uniform segment design for a cohesive appearance, low power requirement for energy efficiency, high brightness and contrast for visibility in various lighting conditions, and a wide viewing angle. The solid-state reliability of LED technology ensures long operational life. These features make it suitable for target markets including industrial instrumentation (e.g., panel meters, process controllers), test and measurement equipment, medical devices, automotive dashboards (secondary displays), and consumer appliances where clear numeric indication is critical.

2. Technical Parameters Deep Objective Interpretation

2.1 Photometric and Optical Characteristics

The key photometric parameter is the Average Luminous Intensity (Iv), specified with a minimum of 320 µcd, typical of 700 µcd, and no maximum stated, under a test condition of a forward current (IF) of 1mA. This indicates a bright output suitable for indoor use. The light is characterized as Hyper Red, with a Peak Emission Wavelength (λp) of 650 nm (nanometers) and a Dominant Wavelength (λd) of 639 nm, placing it firmly in the deep red portion of the visible spectrum. The Spectral Line Half-Width (Δλ) is 20 nm, which describes the spectral purity of the emitted light. A Luminous Intensity Matching Ratio (IV-m) of 2:1 is specified, meaning the intensity of the dimmest segment should be no less than half that of the brightest segment within a device, ensuring visual uniformity.

2.2 Electrical Parameters

The primary electrical parameter is the Forward Voltage per Segment (VF), which has a typical value of 2.6V and a maximum of 2.6V at IF=1mA. This is a critical value for designing the current-limiting circuitry. The Absolute Maximum Ratings define the operational limits: a Continuous Forward Current per Segment of 25 mA (with derating above 25°C), a Peak Forward Current of 90 mA under pulsed conditions (1/10 duty cycle), and a maximum Reverse Voltage (VR) of 5V to prevent damage. The Reverse Current (IR) is very low, with a maximum of 100 µA at VR=5V. The total Power Dissipation per segment is limited to 70 mW.

2.3 Thermal and Environmental Specifications

The device is rated for an Operating Temperature Range of -35°C to +85°C and an identical Storage Temperature Range. This wide range ensures functionality in harsh environments. A critical assembly parameter is the maximum Solder Temperature of 260°C for a maximum of 3 seconds, measured 1.6mm below the seating plane, which guides the reflow soldering process.

3. Binning System Explanation

The datasheet states the device is \"Categorized for Luminous Intensity.\" This implies that units are sorted (binned) based on their measured light output at a standard test current. While specific bin codes are not provided in this excerpt, such a system allows designers to select displays with consistent brightness levels for their application, preventing noticeable variations between different units in a product.

4. Performance Curve Analysis

The datasheet references \"Typical Electrical / Optical Characteristic Curves\" which are typically graphical representations of how parameters change under different conditions. Common curves for such a device would include: Forward Current vs. Forward Voltage (I-V Curve): Showing the non-linear relationship, crucial for driver design. Luminous Intensity vs. Forward Current: Showing how light output increases with current, up to the maximum rating. Luminous Intensity vs. Ambient Temperature: Showing the decrease in output as temperature rises, important for thermal management. Spectral Distribution: A graph plotting relative intensity against wavelength, centered around 650nm.

5. Mechanical and Package Information

5.1 Dimensions and Outline

The package drawing (referenced but not detailed in the text) would show the physical outline of the 4-digit display module. Key dimensions include the overall length, width, and height, the digit height of 0.52 inches (13.2 mm), the spacing between digits, and the segment dimensions. Tolerances are generally ±0.25 mm unless otherwise specified.

5.2 Pinout and Connection Diagram

The device has 40 pins. The pin connection table meticulously details the function of each pin, mapping cathodes for segments A-G and the decimal point (D.P.) for each of the four digits (Digit 1 to 4), as well as the common anode for each digit. For example, Pin 1 is the cathode for segment E of Digit 1, while Pin 38 is the common anode for Digit 1. This precise mapping is essential for creating the correct PCB layout and driving software. The internal circuit diagram shows that all segments within a digit share a common anode connection, which is brought out to a single pin per digit.

5.3 Polarity Identification

The device is clearly marked as a Common Anode type. Polarity is identified through the pinout table. Applying a positive voltage to a digit's common anode pin while sinking current through the respective segment cathode pins will illuminate those segments.

6. Soldering and Assembly Guidelines

The key guideline provided is the solder temperature limit: 260°C maximum for 3 seconds, measured 1.6mm below the seating plane. This is a standard profile for lead-free reflow soldering. Designers must ensure their reflow oven profile does not exceed this limit to avoid damaging the plastic package or the internal wire bonds. Standard ESD (Electrostatic Discharge) precautions should be observed during handling. The storage conditions are defined by the storage temperature range.

7. Packaging and Ordering Information

The part number is LTC-5837JD. The \"JD\" suffix may indicate specific binning or other variants. The datasheet does not provide details on tape-and-reel packaging, tray quantities, or labeling. For production, this information would need to be obtained from the manufacturer or distributor.

8. Application Suggestions

8.1 Typical Application Circuits

The common anode configuration is ideal for multiplexed driving. A typical circuit involves using a microcontroller or dedicated display driver IC. The microcontroller would sequentially enable (set to a logic high or connect to Vcc via a transistor) one digit's common anode at a time, while outputting the pattern for the segments (cathodes) of that digit, often through current-limiting resistors or a constant-current sink driver. This multiplexing happens faster than the human eye can perceive, creating the illusion of all digits being on simultaneously, while significantly reducing the number of required microcontroller I/O pins.

8.2 Design Considerations

Current Limiting: Essential to prevent exceeding the maximum continuous forward current (25mA per segment). Resistors or constant-current drivers must be calculated based on the supply voltage and the LED forward voltage (VF). Multiplexing Frequency: Must be high enough to avoid visible flicker, typically above 60-100 Hz. Peak Current: In a multiplexed design, the instantaneous current during the short ON time can be higher than the average DC current. Ensure the peak current does not exceed the 90mA rating. Viewing Angle: The wide viewing angle allows flexibility in mounting position relative to the user. Contrast: The gray face/white segment design provides good contrast; avoid mounting behind deeply tinted windows which would attenuate the red light.

9. Technical Comparison and Differentiation

The primary differentiator of the LTC-5837JD is its use of AlInGaP Hyper Red LED technology. Compared to older technologies like standard GaAsP (Gallium Arsenide Phosphide) red LEDs, AlInGaP offers significantly higher luminous efficiency, resulting in greater brightness for the same input current, or the same brightness at lower power. It also typically provides better wavelength stability over temperature and lifetime. The 0.52-inch digit height is a standard size, but the combination of high brightness, contrast, and the specific gray/white aesthetic may differentiate it from other displays in its class.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the purpose of the \"Hyper Red\" designation?
A: It indicates the LED emits light at a longer wavelength (~650nm) compared to standard red LEDs (~630nm). This deeper red can appear more vibrant and may have better performance in certain optical filter systems.

Q: Can I drive this display with a 5V microcontroller without external drivers?
A: Possibly, but with caution. The typical VF is 2.6V. With a 5V supply, a current-limiting resistor is mandatory. The resistor value R = (Vcc - VF) / IF. For IF=10mA, R = (5 - 2.6) / 0.01 = 240 Ohms. You must also ensure the microcontroller's I/O pins can sink the cumulative segment current when multiple segments are lit in a digit during multiplexing.

Q: What does \"Common Anode\" mean for my circuit design?
A: It means all the anodes (positive sides) of the LEDs for one digit are connected together. To light a segment, you apply a positive voltage to that digit's common anode pin and connect the desired segment's cathode pin to ground (through a current limiter). This is opposite of a common cathode display.

11. Practical Design and Usage Case

Case: Designing a 4-Digit Voltmeter Readout. A designer is building a benchtop power supply and needs a clear voltage display. They select the LTC-5837JD for its brightness and size. The microcontroller (e.g., an ARM Cortex-M or PIC) has limited I/O. Using the multiplexing scheme, they need only 4 pins for the digit anodes (controlled via NPN transistors or MOSFETs) and 8 pins for the segment cathodes (7 segments + decimal point). The firmware scans through digits 1-4 rapidly. The analog-to-digital converter reads the voltage, converts it to a BCD format, and the firmware looks up the corresponding segment patterns from a table, outputting them synchronously with the anode enabling. Current-limiting resistors are placed on the cathode lines. The gray face provides a professional look against the instrument panel.

12. Principle Introduction

A seven-segment display is an assembly of light-emitting diodes (LEDs) arranged in a figure-eight pattern. Each of the seven segments (labeled A through G) is an individual LED. By illuminating specific combinations of these segments, all decimal digits (0-9) and some letters can be formed. In a multi-digit display like this one, each digit is a separate set of segments, but the corresponding segments (e.g., all 'A' segments) are often electrically independent to allow for multiplexed control, which reduces the total number of required connection pins.

13. Development Trends

The trend in seven-segment LED displays continues towards higher efficiency, allowing for brighter displays at lower power consumption, which is critical for battery-powered devices. Integration is another trend, with display driver circuitry, sometimes even including a microcontroller, being incorporated into the display module itself, simplifying system design. There is also a move towards wider color gamuts and the use of advanced materials like AlInGaP and InGaN (for blue/green) to improve performance and reliability. However, for many industrial and instrumentation applications, the classic through-hole design with high-brightness red remains popular due to its proven reliability, excellent contrast, and ease of design.