LSR024T13-S-V1: 2.4-Inch TFT LCD Module with Resistive Touch Panel (RTP), 240x320 Resolution, 262K Colors, 4-Line SPI Interface

Product Subtitle / Keywords:
2.4 Inch Display, QVGA 240x320 Resolution, Transmissive a-Si TFT, 4-line SPI Interface, COG+FPC+B/L+RTP, 262K Colors, 12-pin FPC, ST7789V Driver

1. Executive Summary & Product Positioning

The LSR024T13-S-V1, developed by LESSON (Wan'an) Zhixian Technology Co., Ltd. (立信(万安)智显科技有限公司), is a 2.4-inch transmissive amorphous Silicon TFT-LCD module with an integrated Resistive Touch Panel (RTP).

This product specification book (Revision 1.0, Model No: LSR024T13-S-V1) serves as the definitive technical document, defining its structural composition (COG+FPC+B/L+RTP), mechanical dimensions, absolute maximum ratings, detailed electrical characteristics, 4-line SPI (Serial Peripheral Interface) pinout and timing, and electro-optical performance. It delivers a QVGA resolution of 240(RGB)×320 with 262K-color display capability.

The document provides the core parameters necessary for system integration into embedded display applications. The unequivocal recommendation for engineers is to strictly adhere to the electrical specifications, interface timing, and mechanical tolerances described herein to ensure reliable performance and compatibility.

2. Detailed Product Overview & Architecture

• Core Technology: Transmissive-type a-Si TFT-LCD (amorphous silicon thin film transistor liquid crystal display).
• Display Characteristics: Capable of displaying up to 262 thousand colors.
• Module Construction: COG (Chip-On-Glass) + FPC (Flexible Printed Circuit) + B/L (Backlight Unit) + RTP (Resistive Touch Panel). A fully integrated display and touch solution.
• Interface: 4-line SPI (Serial Peripheral Interface).
• Display Mode: Normally White (inferred from similar models with TFT driver ICs).
• Viewing Direction: 6 o'clock (typical for TN panels).
• Approval Status: Approved Product Specification only (as per signature block).

3. Exhaustive Technical Specifications

3.1 Mechanical & Physical Specifications

(Note: Specific module outline dimensions are referenced in Section 4 (Outline Dimension) of the full specification document but are not fully detailed in the provided context excerpt.)

3.2 Electrical & Interface Specifications

3.2.1 Absolute Maximum Ratings

Notes (interpreted):

• Note1/Note2: Stress beyond these ratings may cause permanent damage; functional operation is not implied under these conditions.

3.2.2 Electrical Characteristics (DC – Recommended Operating Conditions)

(Note: The DC table refers to VDD rather than VCC in the absolute max table. The supply voltage IOVCC value is referenced in the VIL/VIH formulas but its specific range is not explicitly defined in the provided excerpt. It is typically 1.8V or 3.3V for such interfaces.)

3.2.3 Pin Description (18-pin FPC from Mechanical Drawing)

Interface Summary:

• SPI Interface: This is a 4-line SPI interface with a dedicated output pin (SDO) – a true 4-line interface with separate data input (SDA) and data output (SDO) lines. This allows for full-duplex or read-back operations.
• Backlight: The backlight uses a single anode pin (Pin 10) and 4 separate cathode pins (Pins 11-14) connected together. This suggests a configuration where 4 LED strings are driven in parallel.
• Resistive Touch Panel: Pins 15-18 provide a standard 4-wire resistive touch screen interface (XL, YU, XR, YD).

3.2.4 Serial Interface Timing Characteristics (4-line serial)

Conditions: VDDI=1.65 to 3.3V, VDD=2.4 to 3.3V, AGND=DGND=0V, Ta=25°C.

(Note: The specific setup/hold times (T_CSS, T_CSH, T_SDS, etc.) and clock cycle times for the SPI interface are listed as "TBD" (To Be Determined) in the provided excerpt. The final production specification would define concrete values. The table references VDDI and VDD conditions, confirming the dual supply requirements.)

3.2.5 Backlight Unit

Note: The backlight requires a constant-current driver set to 80 mA typical, with a forward voltage range of 2.9V to 3.4V. The "Modified backlight" note from the mechanical drawing ("修改了背光") suggests this version may have a different backlight configuration compared to previous revisions.

3.3 Resistive Touch Panel (RTP) Interface

The module includes a 4-wire resistive touch screen controlled via the following pins:

Working Principle: The host system requires an external touch screen controller (ADC) to measure the voltage ratios across these pins when a touch is detected. Common controllers include TSC2046, ADS7843, or an MCU with built-in analog inputs.

4. Application Guidelines & Critical Notes

Intended Use

• Consumer electronics (portable gaming devices, smart home controls)
• Industrial HMIs requiring basic touch input
• Handheld instruments and measurement devices
• Point-of-sale (POS) terminals
• Any application requiring a cost-effective, small color display with integrated resistive touch

Critical Design Considerations

1. Power Supply:

   • Provide a stable VDD (2.4-3.3V, 2.8V typical) for the LCM logic.
   • The backlight requires a separate constant-current LED driver capable of sourcing 80 mA at approximately 2.9-3.4V.
   • Note the 4 separate cathode pins (K) – all 4 must be connected to the current sink output of the LED driver.

2. SPI Interface:

   • This is a true 4-line SPI interface with separate SDA (data input) and SDO (data output) pins. This allows for read-back of register values and display memory, unlike simpler 3-line interfaces.
   • The host MCU's SPI peripheral must be configured in Mode 0 or Mode 3 (CPOL=0, CPHA=0 or CPOL=1, CPHA=1) – verify from the datasheet of the driver IC (likely ST7789V).
   • The RS pin (Pin 4) selects between command (Low) and data (High) writes.

3. Resistive Touch Panel Integration:

   • The host system requires a touch screen controller to interface with the 4-wire resistive panel. This can be an external IC (e.g., TSC2046) or the host MCU's own ADC with GPIO control.
   • The touch panel pins (XL, YU, XR, YD) are typically connected through a multiplexer within the touch controller.
   • Calibration will be required in software to map touch coordinates to display coordinates.

4. Reset Circuit:

   • The RESET pin (Pin 2) must be driven low for a sufficient period (typically >10 µs) during power-up. A simple RC circuit (10kΩ resistor to VDD, 1µF capacitor to GND) or an MCU GPIO is recommended.

5. Backlight Drive:

   • The backlight uses 4 cathode pins in parallel, suggesting the 4 LEDs are connected in a single string or multiple parallel strings.
   • The drive condition is 80 mA typical at 2.9-3.4V forward voltage.
   • Design a constant-current LED driver with current set to 80 mA. The compliance voltage of the driver must be capable of reaching the maximum forward voltage of 3.4V.

6. Mechanical Integration:

   • Note the multiple cathode pins (Pins 11-14) – ensure all 4 are properly connected in the PCB layout to handle the backlight current.
   • The module includes a resistive touch panel (RTP) – consider the total thickness of the assembly in enclosure design.
   • The "黄色绝缘胶纸" (yellow insulating tape) and "易撕贴手撕位" (tear-off sticker) on the mechanical drawing indicate areas requiring careful handling to avoid damage during manufacturing.

7. Temperature Limits:

   • Operating Temperature: -10°C to +70°C.
   • Storage Temperature: -20°C to +80°C.

Handling & Compliance

• The module is ROHS compliant (implied from similar document standards).
• Observe standard ESD precautions during handling and assembly.
• The module contains fragile glass and a resistive touch panel – handle with care to avoid scratches on the touch surface.
• The FPC is delicate – avoid bending sharply, especially at the connector interface.

5. Conclusion & Design-In Support

The LSR024T13-S-V1 specification details a 2.4-inch QVGA display module with an integrated 4-wire resistive touch panel and a true 4-line SPI interface with separate data output (SDO).

Key Strengths:

1. Integrated Resistive Touch Panel: Eliminates the need for a separate touch overlay, simplifying mechanical design and reducing overall device thickness.
2. True 4-Line SPI with SDO: The dedicated data output pin (SDO) enables register read-back and display memory reads for more advanced software control.
3. Standard QVGA Resolution: 240x320 is a widely supported resolution across many driver ICs, ensuring compatibility with existing libraries.
4. Well-Defined Pinout: The 18-pin FPC provides dedicated pins for display control, backlight, touch panel, and power, simplifying PCB design.
5. 4 Separate Backlight Cathode Pins: Provides flexibility for backlight current distribution and thermal management.

Main Design Focus:

• Touch Controller Interface: The most critical design task is integrating a 4-wire resistive touch screen controller to read the analog touch signals and convert them to digital coordinates.
• SPI Driver Development: Software engineers must initialize the display driver IC (likely ST7789V) via the SPI interface, configure the correct operating mode, and implement the touch calibration algorithm.
• Power Management: Provide stable VDD (2.8V) power and a constant-current backlight driver set to 80 mA.
• Mechanical Integration: Ensure the housing design accommodates the touch panel surface and includes proper support to prevent pressure on the LCD active area.

This module is an excellent, cost-effective solution for applications requiring a compact color display with basic touch input capability.