Comprehensive Technical Specification & Application Guide

1. Executive Summary & Product Positioning

The LSL024I21-MP-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.

This product specification book (Revision 1.0, Part Number 50.55.SMX00000R) serves as the definitive technical document, defining its structural composition (COG+FPC+B/L+LENS), precise mechanical dimensions, absolute maximum ratings, detailed electrical characteristics, complete MIPI DSI (Display Serial Interface) pinout, timing parameters, and electro-optical performance. It delivers a QVGA resolution of 240(RGB)×320 with 262K-color display capability.

The document provides a complete set of technical indicators for design, production, and quality inspection. The unequivocal recommendation is to strictly adhere to the mechanical specifications, absolute maximum ratings, power supply conditions, and interface timing described herein to ensure reliable operation and integration.

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) + LENS. This indicates a module with an integrated cover lens.
• Interface: MIPI DSI (Display Serial Interface) – a modern high-speed differential serial interface.
• Panel Size: 2.4 inch diagonal.
• Approval Status: Approved Product Specification only (as per signature block).

3. Exhaustive Technical Specifications

3.1 Mechanical & Physical Specifications

(Note: The module includes a LENS, hence the total thickness of 4.03mm, which is thicker than a bare LCD module.)

3.2 Electrical & Interface Specifications

3.2.1 Absolute Maximum Ratings

Critical Note: The absolute maximum ratings are limits at which permanent damage will occur. Functional operation is not implied at these limits.

3.2.2 Electrical Characteristics (Recommended Operating Conditions – DC)

3.2.3 Pin Description (40-pin FPC)

Interface Summary: This is a MIPI DSI 1-lane interface (one data lane: D0P/N, one clock lane: CLKP/CLKN).

3.2.4 MIPI Interface Low Power Mode Timing Characteristics

Conditions: VDDI=1.8V, VDD=2.8V, AGND=DGND=0V, Ta=25°C.

Visual Timing Diagrams (Referenced in Document):

The document includes detailed timing diagrams for:

Figure 11: Data lanes – Low Power Mode to/from High Speed Mode Timing

This diagram shows the transition sequence for data lanes (DSI-D0+/-):

• LP-11 (Low Power idle state)
• LP-01 → LP-00 (Mark-1 to Space state - for HS request)
• T_LPX (Length of LP period)
• T_HS-PREPARE (Time to prepare for HS)
• T_HS-ZERO (HS-0 before first sync)
• T_HS-SYNC (HS sync pattern)
• HS Data transmission
• T_HS-TRAIL (HS trail period)
• T_HS-EXIT (HS exit to LP)
• Return to LP-11

Figure 12: Clock lanes – High Speed Mode to/from Low Power Mode Timing

This diagram shows the clock lane (DSI-CLK+/-) transition:

• LP-11 → LP-00 (Start)
• T_CLK-PREPARE (Time to prepare clock)
• T_CLK-ZERO (Before clock starts)
• T_CLK-PRE (Before HS data)
• HS Clock burst
• T_CLK-POST (After last HS data)
• T_CLK-TRAIL (Clock trail period)
• T_HS-EXIT (Exit to LP)
• T_CLK-TERM-EN (Enable termination)

The timing diagrams are critical for the display driver initialization and for ensuring proper MIPI DSI bus communication.

3.3 Backlight Unit

Note: The backlight driving conditions (Forward current, Forward voltage, number of LEDs) are not explicitly provided in the context excerpt. The backlight is powered via the LED+ (Pins 35-36) and LED- (Pins 28-29) pins. A constant-current driver is required.

4. Application Guidelines & Critical Notes

Intended Use

• Smartphones, feature phones, portable media players
• Compact industrial HMIs
• IoT devices with advanced graphical user interfaces
• Any application requiring a small, color display with a high-speed serial interface

Critical Design Considerations

1. MIPI DSI Host Required:

   • This module requires a host processor, GPU, or bridge chip with a MIPI DSI transmitter.
   • It is NOT compatible with simple parallel RGB, SPI, or MCU interfaces without a converter/bridge IC.

2. Dual Power Supplies:

   • Provide clean, stable power for VCC (2.4-3.3V, 2.75V typical) for the core logic.
   • Provide power for 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 LED+ and LED- pins.

3. Signal Integrity – CRITICAL:

   • The MIPI differential pairs (D0P/N, CLKP/CLKN) run at high speed.
   • On the host PCB: Ensure 100Ω differential impedance for each pair.
   • Length matching: Match the trace lengths within each differential pair to within 0.5mm-1mm.
   • Grounding: Ensure proper return current paths by providing solid ground planes beneath the traces.
   • Keep away: Route MIPI traces away from noisy signals (clocks, switching regulators).

4. Power Sequencing:

   • Follow the proper power-up sequence: IOVCC → VCC → RESET → MIPI Data/Clock → Backlight.
   • For power-down: Backlight → MIPI Data/Clock → VCC → IOVCC.

5. Reset Circuit:

   • The RESET pin (Pin 24) must be driven low for a sufficient period (typically >10 µs) during initialization.

6. Unused Pins:

   • Pins 5, 6, 11, 12, 14, 15, 20-23, 25, 26, 31, 34, and 40 are marked NC (No Connection). These should be left floating in your design.

7. Mechanical Integration:

   • Note the module thickness is 4.03mm due to the integrated LENS.
   • Ensure the housing design provides support for the module while avoiding pressure on the active display area.

8. Temperature Limits:

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

5. Conclusion & Design-In Support

The LSL024I21-MP-V1 specification details a 2.4-inch QVGA display module with an integrated LENS and a modern MIPI DSI interface.

Key Strengths:

• MIPI DSI Interface: Allows for high-speed data transfer with fewer pins (1-lane) compared to parallel RGB or MCU interfaces, reducing EMI and simplifying PCB routing.
• Integrated LENS: The module comes with a pre-assembled cover lens, simplifying mechanical integration and providing protection for the display surface.
• Detailed MIPI Timing Diagrams: The inclusion of Figures 11 and 12 provides critical guidance for software engineers to correctly initialize and communicate with the display driver.
• Standard 240x320 QVGA Resolution: Well-suited for classic smartphone or small embedded display applications.

Main Design Challenges:

• Requires a host processor with a MIPI DSI transmitter, which is less common on low-cost microcontrollers compared to SPI or parallel interfaces.
• Careful attention must be paid to PCB layout for high-speed signal integrity (impedance control, length matching).
• A constant-current LED backlight driver is required.

This module is an excellent choice for mid-to-high-end embedded systems where a small, high-quality, high-speed display with an integrated lens is needed.