Graphic COG LCD Technology

Monochrome Chip-on-Glass graphic LCD modules from 1.87" to 5.18", with resolutions from 132x32 to 320x240. Find out how COG construction works, and how to choose a controller, interface and connection.

Overview

A graphic COG (Chip on Glass) LCD is a monochrome dot matrix display in which the driver and controller IC is bonded directly onto the display glass. There is no separate controller PCB behind the panel, so the module is thinner, lighter and has fewer parts than a traditional COB (Chip on Board) LCD. A thin flexible printed circuit (FPC) or a row of metal pins connects the display to your host board.

As the authorised distributor for Winstar Display Corporation we offer graphic COG LCD modules from the 1.87" 128x64 WO12864P up to the 5.18" 240x64 WO24064A1, including square, wide and circular formats. Each module has an on-glass controller supporting I²C, SPI or 6800/8080 parallel interfaces, an LED backlight, and a choice of STN and FSTN display modes.

Controller bonded directly to the glass

Resolutions from 132x32 to 320x240

I²C, SPI and 6800/8080 parallel interfaces

3V and 3.3V logic supply

FPC, metal pin and PCB connection options

Operating range -20℃ to +70℃

Graphic COG at a Glance

Technology: Monochrome STN / FSTN LCD
Sizes: 1.87" to 5.18"
Resolution: 132x32 to 320x240
Controllers: ST7565P, ST7567A, ST7567S, ST75161, ST75256, ST7529, ST7586S, UC1608, UC1698U, RA8835
Interfaces: I²C, SPI, 6800, 8080
Logic supply: 3V or 3.3V (3.3V or 5V on WO320240E)
Backlight: LED
Operating temp: -20℃ to +70℃

How a COG LCD Works

An LCD is a light valve. A thin layer of liquid crystal sits between two sheets of glass, with polarisers on the outside. Applying a voltage across a pixel twists the liquid crystal and changes how much light passes through, so the pixel appears dark or light against the background. An LED backlight behind the panel lights the display in the dark.

In a COG module the bottom glass is made slightly larger than the top glass, leaving a ledge. The controller IC is bonded straight onto that ledge with anisotropic conductive film, and connects to the row and column electrodes printed on the glass. The controller stores the image in its own memory and drives the display at a set duty cycle, for example 1/65 for a 128x64 panel, so your microcontroller only writes data when the picture changes.

Simplified illustration, not to scale: layer thicknesses are exaggerated for clarity

Advantages of Graphic COG LCDs

Why designers choose Chip on Glass for compact graphic displays

Thin & Compact

With no controller PCB behind the glass, modules such as the WO12864A1 are just 5.01mm deep including the backlight.

Lightweight

Fewer parts and no PCB mean a lighter module, ideal for handheld and portable equipment.

Low Power

Monochrome LCDs draw very little current from a 3V or 3.3V logic supply, suiting battery powered devices.

Built-in Controller

The on-glass controller holds the image in memory and generates the LCD drive voltage, so few external parts are needed.

Readable in Bright Light

Positive transflective FSTN types use ambient light as well as the backlight, staying readable in bright conditions.

Easy Upgrades

Several models share outlines with earlier displays, such as the 256x128 WO256128A and the 128x64 WO12864D3.

Choosing a Connection

Most COG modules connect through an FPC tail, which keeps the module thin and lets the display sit away from the main PCB. Some models use metal pins for direct soldering, and some come on a small PCB with mounting holes.

A connection board is also available to change the interface from FPC to pins or cables, with a variety of pin out connections to suit your design.

Connection	Example	Best Suited To
FPC tail	WO12864P, WO13232A, WO128128A	Thinnest designs, flexible placement
Metal pins	WO160160B	Direct soldering to the host PCB
COG on PCB	WO240160A	Mounting holes, simple installation
Connection board	Optional for FPC models	Converting FPC to pins or cables

Choosing an Interface

The controller sets which interfaces a module supports, and many support several, selected by pin settings. I²C needs only two signal lines, SPI is faster, and 8-bit parallel gives the highest throughput where your microcontroller has the pins to spare.

Our engineers can help match a display, controller and interface to your design and arrange samples.

Ask Our Engineers

Interface	Signal Lines	Best Suited To
I²C	2 (clock, data)	Low pin count MCUs, small displays
SPI (3 or 4-line)	3 to 4	Faster updates with few pins
6800 / 8080 parallel	8 data + control	Highest throughput, 320x240 displays

Graphic COG LCD Range

Compare our graphic COG LCD modules by size, resolution, controller, interface and outline

Model	Size	Resolution	Controller	Interface	Outline (mm)
WO12864P	1.87"	128x64	ST7567S	6800, 8080, 4-line SPI	55.2 x 39.8 x 6.0
WO13232A	2.15"	132x32	ST7567A	I²C	65.4 x 28.2 x 9.7
WO12864A1	2.24"	128x64	ST7565P	6800, 8080, 4-line SPI	60.1 x 44.5 x 5.01
WO128128A	2.45" round	128x128	ST75161	6800, 8080, SPI, I²C	55.0 x 57.0 x 6.18
WO256128A	2.93"	256x128	ST75256	6800, 8080, 4-line SPI, I²C	80.0 x 54.0 x 9.5
WO160160B	3.03"	160x160	UC1698U	6800, 8080	82.2 x 77.5 x 7.43
WO240160A	3.24"	240x160	ST7529	6800, 8080	93.0 x 64.2 x 9.8
WO240128A	3.75"	240x128	UC1608	6800, 8080, 3 or 4-line SPI	98.7 x 67.7 x 9.5
WO320240E	3.77"	320x240	RA8835	6800, 8080	94.7 x 83.3 x 9.4
WO32032A	4.24"	320x32	ST7586S	3 or 4-line SPI	114.32 x 27.56 x 5.6
WO24064A1	5.18"	240x64	ST7565P	6800, 8080, 4-line SPI	142.5 x 51.7 x 14.9

Outline thickness is the maximum, including backlight. See the datasheet or contact us for details. View Graphic COG LCD Modules →

1.87"

Smallest Display

320x240

Highest Resolution

Logic Supply

Models in Range

Typical Applications

Graphic COG LCDs suit compact devices that need a clear, low power display

Handheld Instruments

Meters, testers and portable instruments where size, weight and battery life matter.

Medical Devices

Monitors, pumps and personal medical devices with simple graphic user interfaces.

Industrial Equipment

Control panels, automation systems and machine status displays.

Measurement & Test

Gauges, data loggers and measurement instruments, including round displays for dials.

Handheld Terminals

Scanners, data terminals and portable equipment needing a larger graphic area.

Control & Monitoring

Thermostats, energy meters and monitoring systems showing icons and status messages.

Frequently Asked Questions

COG stands for Chip on Glass. The LCD driver and controller IC is bonded directly onto a ledge of the display glass, rather than onto a separate PCB. Signals reach the host through a thin flexible printed circuit (FPC) or metal pins, giving a thin, light and compact display module.

Choose COG where space, weight and thickness matter, such as handheld and portable equipment. Choose COB (Chip on Board) where you want a rigid PCB with mounting holes and header pins that is easy to fit and hand solder, or where you are matching an existing COB outline.

I2C needs only two signal lines and suits low pin count microcontrollers, as on the WO13232A. SPI uses 3 or 4 lines and gives faster updates. 6800 or 8080 8-bit parallel gives the highest throughput for larger displays such as the 320x240 WO320240E. Many modules support several interfaces, selected by pin settings.

Usually not. COG controllers such as the ST7586S in the WO32032A include a booster circuit that generates the LCD drive voltage from the 3V logic supply, so contrast can be adjusted in software. The WO320240E includes a built-in negative voltage generator and runs from 3.3V or 5V.

In several cases, yes. The 256x128 WO256128A shares the outline, view area and 3.3V supply of the 128x64 WO12864D3, giving twice the resolution in each direction. The WO12864P is an alternative to the WO12864C2 with the same dimensions, view area, active area and interface options.

Graphic COG LCD Technology

Overview