Product Subtitle / Keywords:
2.4 Inch Display, QVGA 240x320 Resolution, Transmissive a-Si TN TFT, SPI Interface, COG+FPC+B/L, 262K Colors, ST7789T3 Driver, 12-pin FPC, -20°C~70°C Operating Temperature

1. Executive Summary & Product Positioning

The LS024T27-S-V2, 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.

This product specification book (Revision 1.0, Model No: LS024T27-S-V2) serves as the definitive technical document, defining its structural composition (COG+FPC+B/L), mechanical dimensions, absolute maximum ratings, detailed electrical characteristics, SPI (Serial Peripheral Interface) pinout and timing, and comprehensive electro-optical performance. It delivers a QVGA resolution of 240(RGB)×320 with 262K-color display capability, driven by the ST7789T3 controller.

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 Mode: Active matrix TFT, Transmissive type.
• Display Characteristics: Capable of displaying up to 262 thousand colors.
• Module Construction: COG (Chip-On-Glass) + FPC (Flexible Printed Circuit) + B/L (Backlight Unit). Composed of a TFT-LCD panel, a driver circuit, and a backlight unit.
• Interface: SPI (Serial Peripheral Interface) – Input Data format.
• Viewing Direction (Grayscale Inversion): TN (Twisted Nematic).
• Drive IC: ST7789T3.
• Backlight: FORE series and ONE parallel white LED.
• Approval Status: Approved Product Specification only (as per signature block).

3. Exhaustive Technical Specifications

3.1 Mechanical & Physical Specifications

Critical Mechanical Design Notes (from document):

1. Display Type: TN TFT.
2. Operating Temperature: -20°C ~ +70°C.
3. Storage Temperature: -30°C ~ +80°C.
4. Main LCD Driver: ST7789T3.
5. Backlight: FORE series and ONE parallel white LED.
6. ROHS Compliance: Yes.
7. Bezel Opening Design: It is recommended that the housing's visible area be at least 0.3mm smaller per side than the module's viewing area (VAMds).
8. Foam Gasket Cutout Design: The cutout in the chassis foam gasket should be at least 0.6mm larger per side than the module's viewing area (VAMds).
9. TP/Conductor Isolation: The Touch Panel (TP) edges must not come into contact with any metal conductors.
10. Glass Segment to Edge Tolerance: ±0.2 mm.

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)

3.2.3 Pin Description (12-pin FPC)

Interface Summary:

• SPI Interface: This is a 4-line SPI interface with dedicated pins for CS (Chip Select), SCL (Clock), SDA (Data Input), and D/C (Data/Command). It also includes a dedicated SDO (Data Output) pin for read-back operations.
• Backlight: The backlight uses a single anode pin (Pin 12, BL_A) and 2 separate cathode pins (Pins 10-11, BL_K1 and BL_K2). This suggests a configuration where the backlight LEDs are divided into two parallel strings.

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.

A. Write Operation Timing:

B. Read Operation Timing:

Key Observation: The write cycle minimum is a very fast 16ns (62.5 MHz), while the read cycle is significantly slower at 150ns (6.67 MHz). This is typical for SPI display controllers.

3.2.5 Backlight Unit

Note: The backlight configuration is described as "FORE series and ONE parallel white LED". This likely means the backlight consists of multiple LEDs arranged in a series-parallel configuration. The two cathode pins (BL_K1 and BL_K2) suggest two parallel paths. A constant-current LED driver is required. The specific drive current (I_F) and forward voltage (V_f) are not explicitly stated in the provided excerpt but would be defined in the full specification's optical characteristics table.

3.3 Optical & Electro-Optical Characteristics (Ta=25°C)

Notes (from document):

1. Response Time: Ambient temperature = 25°C. Measured at the center point of the panel.
2. Contrast Ratio (CR): To be measured with a viewing cone of 2° by Topcon luminance meter BM-5A.
3. Viewing Angle: Asymmetric viewing angles typical for TN panels: Top (45°), Bottom (20°), Left (45°), Right (45°). The best viewing direction is from the top.
4. Luminance: Measured at the center point of the panel with a backlight drive current of 80 mA. The luminance specification is 350 cd/m² (Typ.).

3.4 Version Record

4. Application Guidelines & Critical Notes

Intended Use

• Consumer electronics (portable gaming devices, smart home controls)
• Industrial HMIs and control panels
• Handheld instruments and measurement devices
• IoT devices with graphical user interfaces
• Any application requiring a standard 2.4-inch color display with a simple SPI interface

Critical Design Considerations

1. Power Supply:

   • Provide a stable VCC (2.4-3.3V, 2.75V typical) for the main logic.
   • Provide a stable IOVCC (1.65-3.3V, 1.8V typical) for the I/O interface.
   • The backlight requires a separate constant-current LED driver connected to the BL_A (Anode) and BL_K1/BL_K2 (Cathodes) pins. The drive current is 80 mA (from optical test condition).

2. SPI Interface:

   • This is a 4-line SPI interface with dedicated SDA (data input) and SDO (data output) pins, enabling read-back operations.
   • The host MCU's SPI peripheral must be configured to meet the fast write timing: 16ns clock cycle (62.5 MHz).
   • Note the significantly slower read timing: 150ns clock cycle (6.67 MHz).
   • The D/C pin (Pin 4) selects between command (Low) and data (High) writes.

3. Backlight Drive:

   • The backlight uses 2 separate cathode pins (BL_K1 and BL_K2). Both must be connected to the current sink output of the LED driver.
   • The drive condition from the optical table is 80 mA typical. The forward voltage (V_f) is not explicitly stated but is typically around 3.0V for white LEDs.
   • Design a constant-current LED driver capable of sourcing 80 mA with a compliance voltage sufficient for the LED forward voltage.

4. Reset Circuit:

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

5. Mechanical Integration:

   • Bezel Opening: Design the housing window 0.3mm smaller per side than the viewing area (VAMds) to hide the non-active edges.
   • Foam Gasket Cutout: The cutout should be 0.6mm larger per side than the viewing area to avoid applying pressure on the display surface, which can cause optical defects (Mura).
   • TP Isolation: Ensure the Touch Panel (TP) edges do not contact any metal conductors to prevent short circuits or interference.

6. Temperature Limits:

   • Operating Temperature: -20°C to +70°C.
   • Storage Temperature: -30°C to +80°C.

7. Viewing Angle Consideration:

   • This is a TN panel with asymmetric viewing angles: Top (45°), Bottom (20°), Left (45°), Right (45°).
   • The best image quality is obtained when viewing from the top direction (12 o'clock). The bottom viewing angle is limited (20°), which should be considered in the product's mechanical orientation.

Handling & Compliance

• The module is ROHS compliant.
• Observe standard ESD precautions during handling and assembly.
• The module contains fragile glass and a flexible PCB (FPC) – handle with care.
• Avoid bending the FPC sharply, especially near the connector interface.

5. Conclusion & Design-In Support

The LS024T27-S-V2 specification details a standard 2.4-inch QVGA TN display module with a 4-line SPI interface and the ST7789T3 driver IC.

Key Strengths:

1. Standard QVGA Resolution (240x320): Widely supported resolution across many driver ICs and software libraries.
2. Fast SPI Write Speed: The 16ns write clock cycle allows for high-speed screen updates.
3. Dedicated SDO Pin: Enables register read-back and display memory reads for advanced software control.
4. Well-Defined Pinout: The 12-pin FPC provides dedicated pins for display control, backlight (with 2 cathode pins), and power.
5. Clear Mechanical Guidelines: Explicit recommendations for bezel opening and foam cutout dimensions simplify enclosure design.
6. Version History: The document is Revision 00 (New released on 2025-5-14), indicating it is the initial release of this model.

Main Design Focus:

• SPI Driver Development: Software engineers must initialize the ST7789T3 driver IC via the SPI interface, configure the correct operating mode, and implement the display buffer management.
• Power Management: Provide stable VCC (2.75V) and IOVCC (1.8V) power, and a constant-current backlight driver set to 80 mA.
• Mechanical Integration: Follow the bezel opening and foam cutout guidelines to ensure optimal display quality and prevent optical defects.
• Viewing Angle Consideration: Design the product orientation to take advantage of the best viewing direction (top/12 o'clock) for the TN panel.

This module is a reliable, cost-effective solution for a wide range of embedded display applications requiring a standard 2.4-inch color display with a simple SPI interface.