4 inch Bar TFT Display 400×960 ST7701S MIPI

Product Overview

The Bar TFT Display is a 4.0-inch TFT color LCD module from HOTHMI (model: TFT-H040A13ZDIST6N20). This screen features a high resolution of 400×960 and normally black transmissive technology, delivering 16.7M colors with the ST7701S driver IC. It adopts an advanced MIPI 4-Lane high-speed serial interface, operates at VCI=3.3V and IOVCC=1.8V, and is equipped with a backlight system consisting of 8 LEDs in series, providing a typical high brightness of 600 cd/m² for excellent readability in bright indoor environments.

The Bar TFT Display module offers full viewing angles in all directions, has a slim and lightweight structure, with overall dimensions of just 101.58mm × 41.40mm × 2.04mm and an active display area of 94.03mm × 39.18mm. Additionally, it supports an ultra-wide operating and storage temperature range from -30℃ to +80℃, ensuring high stability and long-term reliability even in harsh conditions, making it widely suitable for smart instrumentation and various outdoor industrial control terminals.

Product Highlights

• Unique Bar TFT Display Form Factor：Unlike conventional square screens, this display is specifically designed to meet the modern hardware demands for slim, refined, and compact structures. It maximizes space utilization in industrial racks, bar-style dashboards, and smart home wall switches.
• IPS Full Viewing Angle Technology：The Bar TFT Display module supports full-angle operation, ensuring that no color distortion, grayscale inversion, or severe brightness drop occurs when viewed from any angle or side, greatly enhancing operational safety for equipment users.
• 600 nits High Brightness：With an integrated backlight system composed of 8 high-efficiency LEDs in series, the module delivers a stable 600 cd/m² high brightness output, ensuring clear visibility even in brightly lit environments.
• MIPI DSI High-Speed Transmission and Low EMI：Utilizing a MIPI 4-Lane serial interface, this Bar TFT Display significantly reduces the number of cable pins (down to 20-Pin) compared to traditional RGB 24-bit parallel interfaces. It provides hundreds of megabits of bandwidth, perfectly supporting high-frame-rate, low-latency dynamic UI refreshes while effectively lowering system electromagnetic interference.
• -30℃ to 80℃ Industrial-Grade Wide-Temperature Design：Built with extreme-temperature-resistant liquid crystal materials and high-standard polarizers, this module operates stably in harsh environments ranging from -30℃ to +80℃. It withstands severe cold and intense heat, greatly extending the service life of outdoor terminals and industrial control equipment.

FPC Pin Description (20-Pin Pin Definition)

The module connects to the main board via a 20-Pin flexible printed circuit with a 0.5mm pitch.

Target Applications

Thanks to its unique Bar TFT Display slim form factor and rugged industrial-grade specifications, this module is widely used in the following demanding fields:

• Smart Industrial Instruments: Power grid testers, benchtop digital multimeters, gas chromatograph panels, and precision measurement devices that leverage the vertical high resolution to display complex waveform data.
• Medical Monitoring and Laboratory Equipment: Bar-type secondary screens for oximetry/heart rate modules, infusion pump status displays, and side control bars for portable ultrasound machines.
• Smart Home Wall Controllers: Embedded wall-mounted bar switches, multifunctional thermostats, and vertical status display bars for kitchen appliances.

Technical Q&A of the Bar TFT Display

Q1: Why does this Bar TFT Display show a black screen or no display at all when powered on?

A1: MIPI interface screens based on the ST7701S chip have very strict timing and initialization code requirements during debugging. Please check the following in order:

Voltage Supply: Use a multimeter to ensure Pin 2 (VCI) has a stable 3.3V and Pin 4 (IOVCC) has 1.8V.

Hardware Reset: Confirm that the RESX reset pin has received a standard low-level pulse (typically pulled low for at least 10ms and then pulled high).

Initialization Sequence: The external register parameters and high-speed clock configuration (D-PHY) of the ST7701S must strictly match the 400×960 spatial resolution.

Q2: Can the backlight driver pins (LEDA/LEDK) be directly connected to a 5V or 12V power supply on the main board?

A2: Absolutely not! The backlight system of this screen consists of 8 high-brightness LEDs connected in an “8-series, 1-parallel” configuration. The typical driving voltage required is as high as Vf = 22.5V ~ 27.2V. You must design a boost constant-current driver circuit on the main board (e.g., using a dedicated LED backlight driver IC) and strictly limit its output current to a constant If = 20mA. Directly connecting to a constant voltage source or insufficient voltage will not only fail to light up the backlight but may also burn out the internal LED light bar on the FPC.