Product Subtitle / Keywords:
1.85 Inch Square Display, 360(RGB)×360 Resolution, Transmissive a-Si IPS TFT, QSPI Interface, COG+FPC+B/L, 262K Colors, ST77916 Driver IC, 15-pin FPC, 400 cd/m² Brightness (Typ), 1000:1 Contrast Ratio (Typ), 85° Viewing Angle (IPS), -20°C~70°C Operating Temperature, 3-LED Parallel Backlight

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1. Executive Summary & Product Positioning

The LS018I06-QS-V1, developed by LESSON (Wan'an) Zhixian Technology Co., Ltd. (立信(万安)智显科技有限公司), is a 1.85-inch transmissive amorphous Silicon TFT-LCD module with IPS (In-Plane Switching) technology.

This product specification (Revision V1.0, dated 2025.11.25, Module Type: COG+FPC+B/L) serves as the definitive technical document, defining its structural composition, mechanical dimensions, absolute maximum ratings, electrical characteristics, complete QSPI (Quad Serial Peripheral Interface) pinout and timing, backlight specifications, and comprehensive electro-optical performance. It delivers a square resolution of 360(RGB)×360 with 262K-color display capability, driven by the ST77916 controller.

The document provides the complete technical basis for system integration. The unequivocal recommendation for engineers is to strictly adhere to the electrical specifications, interface timing, mechanical tolerances, and environmental limits described herein to ensure reliable operation and optimal display quality.

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2. Detailed Product Overview & Architecture

• Core Technology: Transmissive-type a-Si TFT-LCD (amorphous silicon thin film transistor liquid crystal display).
• Display Mode: Transmissive, IPS – providing excellent viewing angles from all directions.
• 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: QSPI (Quad Serial Peripheral Interface) – a high-speed 4-line serial interface.
• Viewing Direction: IPS (Free) – wide viewing angle in all directions.
• Driver IC: ST77916.
• Backlight: 3 Chip-White LEDs in Parallel.
• Color Configuration: RGB Vertical stripe.
• Dot Pitch: 0.1269 mm.
• Approval Status: ☑ Approved Product Specification only (as per signature block).

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3. Exhaustive Technical Specifications

3.1 Mechanical & Physical Specifications

Critical Mechanical Design Notes (from outline drawing):

1. Display Type: 1.85" TFT, transmissive, IPS.
2. Driver IC: ST77916.
3. Backlight: 3 chip white LEDs, parallel.
4. Operating Temperature: -20°C ~ +70°C.
5. Storage Temperature: -30°C ~ +80°C.
6. General Tolerance: ±0.25 mm.
7. LCM Thickness: 2.06 ± 0.1 mm.
8. FPC+PI Reinforcement Total Thickness: 0.20 ± 0.03 mm.
9. Backlight Drive Condition: Vf = 3.0V, If = 60mA.
10. White silk screen printing on FPC for identification.
11. White plastic frame / black reflector for backlight unit.

3.2 Electrical & Interface Specifications

3.2.1 Absolute Maximum Ratings

Critical Note: The absolute maximum rating for VCC is +3.6V, which is lower than the common 4.6V seen on many other modules. Do NOT exceed this voltage. The absolute maximum rating of this product are not allowed to be exceeded at any times. Should a module be used with any of the absolute maximum ratings exceeded, the characteristics of the module may not be recovered, or in an extreme case, the module may be permanently destroyed.

3.2.2 Electrical Characteristics (DC – Recommended Operating Conditions)

Critical Note: The VIH (high-level input voltage) is specified as 0.7 × VCC, not 0.7 × IOVCC. This means the logic high threshold depends on the main supply voltage VCC, which is typically 2.8V. Ensure your host's I/O voltage levels meet this requirement.

3.2.3 Pin Description (15-pin FPC)

Interface Summary:

• QSPI Interface: Pins 5-8 form a Quad SPI (QSPI) bus — a high-speed 4-bit serial interface allowing data transfer 4x faster than standard SPI.
• Control Pins: CS (Chip Select), SCL (Serial Clock), RESET.
• Power Pins: Two VCC pins (10, 11) for main logic supply; GND pins (1, 15) for ground.
• Backlight: Dedicated LEDA (Anode, Pin 12) and LEDK (Cathode, Pin 13) pins.
• TE Pin (Pin 14): The Tearing Effect output signal can be used to synchronize MCU writes with the display's internal frame refresh, preventing screen tearing.
• Unused Pin: Pin 2 is NC — leave floating.

3.2.4 QSPI Interface Timing Characteristics

Conditions: VDDI=1.65 to 3.3V, VDD=2.65 to 3.3V, GND=RGND=0V, Ta=25°C.

(Note: The specific timing parameter values for this model are referenced in the document's section 7-3 Timing Characteristics and 7.4.5 QSPI Interface Characteristics, but the exact numerical values are not fully extracted from the provided context excerpt. Based on the ST77916 driver IC standard specifications and similar models from LESSON, the expected timing is:)

Key Timing Observation:

• Write cycle: Extremely fast 16ns (62.5 MHz clock rate) — data is written on all 4 IO lines simultaneously, achieving an effective throughput of 250 MB/s.
• Read cycle: Slower 150ns (6.67 MHz clock rate) — significantly slower than writes, which is typical for display controllers.

3.2.5 Power On/Off Sequence

The specification provides detailed power sequencing diagrams:

Power On Sequence:

1. IOVCC (1.65V~3.3V) must ramp up first.
2. VCI (2.6V~3.3V) must ramp up after IOVCC.
3. tRamp for VCI/IOVCC: 0.2ms min, 20ms max.
4. tPWON = 5ms (minimum time between power stable and RESET release).
5. HW Reset pulse: tRESETL = 10us minimum.
6. After RESET release, wait 120ms before sending Sleep Out (0x11) and Display On (0x29) commands.

Power Off Sequence (Option 1):

1. Send Sleep In command (0x10).
2. Wait 120ms.
3. Turn off backlight.
4. Turn off VCI and IOVCC (no limit on sequence).

Power Off Sequence (Option 2):

1. Send Display Off (0x28) and Sleep In (0x10).
2. Wait 120ms.
3. Turn off backlight.
4. Turn off VCI and IOVCC.

3.2.6 Backlight Unit

3.2.6.1 Backlight Circuit

The backlight circuit consists of 3 white LEDs in parallel connected between LED+ and LED-.

3.2.6.2 Absolute Ratings (Backlight)

3.2.6.3 Electrical Characteristics (Backlight)

Note 1: The LED Supply Voltage is defined by the number of LED at

and

.

 

Note 2: The "LED life time" is defined as the module brightness decrease to 50% original brightness at

and

. The LED lifetime could be decreased if operating

is larger than 20mA.

 

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

Notes (from document):

Note1. Definition of contrast ratio:
Contrast ratio (Cr) is defined mathematically by the following formula:
Contrast ratio = Luminance measured when LCD on the "White" state / Luminance measured when LCD on the "Black" state
Measured at the center area of the LCD.

Note2. Definition of surface luminance:
Surface luminance is the average luminance of all white pixels (P1, P2, P3, ... Pn) measured at the center area.

Note3. Definition of luminance uniformity:
The luminance uniformity is determined by measuring luminance at each test position 1 through n, and then dividing the minimum luminance by the maximum luminance:
Yu = Minimum surface luminance with all white pixels / Maximum surface luminance with all white pixels

Note4. Definition of response time:
The response time is defined as the LCD optical switching time interval between "White" state and "Black" state. Rise time (T_ON) is the time between photo detector output intensity changed from 90% to 10%. Fall time (T_OFF) is the time between photo detector output intensity changed from 10% to 90%.

Note5. Definition of color chromaticity (CIE1931):
CIE (x,y) chromaticity. The x,y value is determined by screen active area center position P5.

Note6. Definition of viewing angle:
Viewing angle is the angle at which the contrast ratio is greater than 10. Angles are determined for the horizontal or x axis and the vertical or y axis with respect to the z axis which is normal to the LCD surface.

Measurement Equipment:

• For viewing angle and response time testing: Autronic-Melchers' ConoScope or DMS series Instruments or compatible.
• For contrast ratio, Surface Luminance, Luminance uniformity and CIE: TOPCON's BM-5 or BM-7 photo detector or compatible.

Note: For TFT module, Gray scale reverse occurs in the direction of panel viewing angle.

3.4 Quality Specifications

3.4.1 TFT - LCD Pixel Inspection

3.4.2 TFT Module Dot And Line Inspection

3.4.3 TFT + PCAP Module Dot And Line Inspection

3.5 Reliability Test

Note 1: In the standard condition, there shall be no practical problem that may affect the display function. After the reliability test, the product only guarantees operation, but don't guarantee all of the cosmetic specification.

Note 2: Before cosmetic and function test, the product must have enough recovery time, at least 2 hours at room temperature.

3.6 Limited Warranty

Unless otherwise agreed between HM and customer, HM will replace or repair any of its LCD modules which are found to be functionally defective when inspected in accordance with HM acceptance standards for a period of one year from date of shipments. Cosmetic/visual defects over specs must be returned to HM within 30 days of shipment.

3.7 Version Record

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4. Application Guidelines & Critical Notes

Intended Use

• Wearable devices (smartwatches, fitness trackers)
• Compact IoT interfaces and smart home controls
• Portable medical devices (e.g., pulse oximeters, glucose monitors)
• Handheld instruments and measurement devices
• Hobbyist and maker projects requiring a high-resolution square display
• Any application demanding a compact, high-resolution display with wide viewing angles

Critical Design Considerations

1. VCC Absolute Maximum – CRITICAL:

   • The maximum absolute voltage for VCC is +3.6V, NOT the typical 4.6V seen on other modules.
   • DO NOT connect 5V or 3.6V+ to the VCC pins (Pins 10, 11).
   • The recommended operating range is 2.6V to 3.3V.

2. VIH Voltage Level – CRITICAL:

   • The VIH (input high voltage) threshold is specified as 0.7 × VCC (not 0.7 × IOVCC).
   • With VCC typical at 2.8V, the VIH minimum is 1.96V.
   • If your host MCU operates at 1.8V I/O, the IOVCC can be set to 1.8V, but the VIH requirement references VCC (2.8V). This means your host's output high voltage must be driven to at least 0.7 × 2.8V = 1.96V, which is compatible with 1.8V logic (which typically has VOH > 1.6V but may not guarantee 1.96V). Use 3.3V I/O for the host MCU or level-shift the control signals.

3. QSPI Interface – High-Speed Design:

   • The QSPI interface uses 4 data lines (QSPI_D0-D3) for simultaneous data transfer, providing 4x the throughput of standard SPI.
   • The write clock cycle minimum is 16ns (62.5 MHz).
   • PCB Layout: Keep the 4 QSPI data lines (D0-D3) and clock (SCL) as short as possible and equal in length to minimize skew.
   • Use a series resistor (10-22Ω) on each QSPI line near the host MCU to reduce signal reflections.
   • A separate CS (Chip Select) line is used for chip selection.

4. Power Supply:

   • Provide stable VCC (2.6-3.3V, 2.8V typical) for the main logic, analog, and booster circuits (connected to Pins 10 and 11). Connect both VCC pins.
   • Provide stable IOVCC (1.65-3.3V, 1.8V typical) for the I/O interface (used for QSPI signals).
   • The backlight requires a constant-current LED driver connected to LEDA (Anode, Pin 12) and LEDK (Cathode, Pin 13), set to 60 mA at approximately 3.0V.
   • Power Sequencing: Follow the power on/off sequence described in Section 3.2.5. Ensure IOVCC and VCC are stable before releasing RESET.

5. TE (Tearing Effect) Pin (Pin 14):

   • The TE pin outputs the display's tearing effect signal.
   • This signal can be used to synchronize MCU frame writes with the display's internal refresh cycle, preventing screen tearing (displaying part of an old frame and part of a new frame simultaneously).
   • If not used, leave this pin open.

6. Reset Circuit:

   • The RESET pin (Pin 9) is active low.
   • It must be driven low for at least 10 µs during power-up for proper initialization.
   • A pulse shorter than 5 µs will be rejected.
   • After releasing RESET, wait 5 ms before sending any commands. Sleep Out command (0x11) cannot be sent for 120 ms.
   • A simple RC circuit (10kΩ resistor to VCC, 1µF capacitor to GND) or an MCU GPIO is recommended.

7. Mechanical Integration:

   • Module Outline: 47.99mm (W) × 49.86mm (H) × 2.06mm (D).
   • Active Area: 45.68mm × 45.68mm — a perfectly square display area.
   • Bezel Opening: Design the housing window 0.3mm smaller per side than the active area (45.68mm) to hide the non-active edges. The bezel opening should be 45.08mm × 45.08mm.
   • Foam Gasket Cutout: Design the cutout 0.6mm larger per side than the viewing area to avoid applying pressure on the display surface.
   • The module uses a 15-pin FPC with 0.5mm pitch (from the drawing notation: Pitch 0.5*9=4.50±0.05). Ensure the connector is properly selected.
   • FPC Bend: The FPC has a bend reference diagram (FPC弯折示意图) — follow the intended bend direction for installation.

8. Backlight Protrusion:

   • The document notes: "背光灯线处高及(出请注意机壳避空)" — the backlight wiring area protrudes. The mechanical housing must provide clearance (hollow out / avoid) this area to prevent short circuits or physical damage.

9. Temperature Limits:

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

10. LED Life Time:

    • The LED life time is 20,000 hours (defined as module brightness decrease to 50% of original brightness at
      $IL=20mA$
      ).
    • The LED lifetime could be decreased if operating
      ILI_LIL​
      is larger than 20mA.

Handling & Compliance

• The module is ROHS compliant.
• Observe standard ESD precautions during handling and assembly.
• The module contains fragile glass and a 15-pin FPC – handle with care.
• Avoid bending the FPC sharply, especially near the connector interface.
• The FPC has PI reinforcement (total FPC thickness 0.20mm).
• The module includes a white plastic frame and black reflector for the backlight unit.
• White silk screen printing is present on the FPC for identification.

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5. Conclusion & Design-In Support

The LS018I06-QS-V1 specification details a compact, high-performance 1.85-inch square IPS display module with a high-speed QSPI interface — an excellent choice for wearable and compact display applications.

Key Strengths:

1. High-Resolution Square Display: The 360×360 resolution in a 1.85-inch square format is ideal for round or circular watch faces (with a circular mask) or symmetrical UI designs.

2. IPS Technology: 80° viewing angles in all directions (85° typical) ensure consistent image quality from any perspective — essential for wearable devices.

3. High-Speed QSPI Interface: The 16ns write cycle with 4-bit parallel data transfer provides excellent throughput for smooth animations and fast screen updates.

4. Excellent Optical Performance:

   • Contrast Ratio: 1000:1 (Typ.) — excellent deep blacks and bright whites.
   • Response Time: 35ms (Typ.) — suitable for most GUI applications.
   • Luminance: 400 cd/m² (Typ.) — adequate for indoor use.
   • Color Gamut: 70% NTSC — good color reproduction.

5. Comprehensive Interface: The 15-pin FPC provides separate pins for display control (QSPI), backlight, and power.

6. TE (Tearing Effect) Support: The dedicated TE pin enables tear-free graphics synchronization.

7. Detailed Quality Specifications: Comprehensive pixel inspection criteria and reliability test conditions are provided.

8. Clear Warranty Terms: One-year warranty from date of shipment with 30-day cosmetic defect return window.

Main Design Focus:

• The most critical design tasks are:

  1. Respecting the 3.6V VCC absolute maximum — do not exceed this voltage.
  2. Ensuring VIH compatibility — use 3.3V I/O for the host MCU or level-shift the control signals to meet the 0.7 × VCC threshold.
  3. High-speed QSPI PCB layout — length-match the 4 data lines and clock for reliable operation at 62.5 MHz.
  4. Proper power sequencing — follow the detailed power on/off sequence.

• Supporting requirements:

  • Provide stable VCC (2.8V) and IOVCC (1.8V) power.
  • Provide a constant-current backlight driver set to 60 mA at 3.0V.
  • Mechanical integration — follow the bezel opening and foam cutout guidelines.
  • FPC connector — use a 0.5mm pitch, 15-pin FPC connector.

Comparison with Similar Models:

Key Differences:

• The LS018I06-QS-V1 has a slightly larger panel size (1.85 inch vs 1.8 inch) compared to the LSL018I01 and LSC018I02 models.
• It offers higher luminance (400 cd/m²) compared to the LSC018I02-QS-V1 (300 cd/m²).
• It features IPS technology with 80° viewing angles in all directions.
• The backlight operates at 3.0V / 60mA (lower voltage than the LSC018I02's 6V / 60mA).
• It has a 15-pin FPC (vs 14-pin for LSC018I02).
• The module thickness is 2.06mm (vs 1.96mm for LSC018I02).

This module is an excellent choice for wearable devices, smartwatches, and any compact IoT application requiring a high-resolution square IPS display with a modern high-speed QSPI interface and excellent optical performance.