What is the driver IC for a 3.18 inch 128x64 COG LCD?

The driver IC for a 3.18 inch 128x64 COG LCD is typically the ST7565R or a compatible variant like the ST7565P or ST7567. These are common for monochrome graphic displays in this size and resolution, especially when using a Chip-on-Glass (COG) package. The ST7565R is a CMOS LCD controller/driver from Sitronix, designed to drive 128x64 dot matrix LCDs with a 65-common and 132-segment output. It supports a 8-bit parallel interface, 4-bit serial, and SPI, making it flexible for many microcontrollers. For the specific 3.18 inch 128x64 cog lcd display, the driver IC is integrated directly onto the glass substrate via COG technology, which reduces the footprint and component count. The ST7565R operates at 2.7V to 5.5V supply voltage, with a typical current consumption of around 0.5 mA to 1.5 mA depending on the display load and operating mode. It includes an internal oscillator, voltage generator for LCD bias, and a temperature compensation circuit to maintain contrast over a range of -20°C to +70°C. The driver IC’s RAM is 132x65 bits, but only 128x64 is used for the visible area, with the extra bits for border or test purposes. The COG bonding process uses anisotropic conductive film (ACF) to attach the driver IC die directly to the glass, which eliminates the need for a separate PCB for the driver, lowering the overall thickness to about 2.0 mm to 2.5 mm for the entire module. This is critical for space-constrained applications like handheld meters, medical devices, or industrial controls. The ST7565R supports both positive and negative voltage outputs for the LCD, with a typical V0 (LCD drive voltage) of 8.5V to 12.5V, adjustable via software commands. The interface speed for SPI can go up to 10 MHz, allowing fast screen updates for animations or data logging. The driver IC also includes a built-in charge pump for generating the negative voltage, so no external negative supply is needed. In terms of reliability, the ST7565R has a mean time between failures (MTBF) of over 100,000 hours under normal operating conditions, based on Sitronix datasheets. The COG package itself is more sensitive to mechanical stress than a standard IC package, so the module often includes a protective epoxy or a metal frame to shield the driver die. The 3.18 inch diagonal size with 128x64 resolution gives a pixel pitch of about 0.48 mm, which is readable for text and simple graphics. The driver IC’s instruction set includes commands for display on/off, start line set, page address set, column address set, and power control. The ST7565R also supports a partial display mode for saving power, where only a portion of the screen is updated. The contrast adjustment is done via a software command that sets the electronic volume register, with 64 steps from 0 to 63. The typical contrast ratio for this display with the ST7565R is around 5:1 to 8:1, depending on the LCD fluid and polarizer quality. The driver IC can drive both static and dynamic images, but it lacks a dedicated hardware accelerator for complex graphics, so all pixel manipulation is done by the host microcontroller. The display’s interface can be configured for 6800-series or 8080-series parallel modes, but the SPI mode is most common for reducing pin count. The SPI wiring uses only 4 pins: CS, SCLK, SID (or MOSI), and A0 (data/command). The reset pin is also required, but it can be tied to the microcontroller’s reset line. The driver IC’s internal oscillator runs at about 1.5 MHz to 2.5 MHz, but you can also use an external clock if needed. The frame rate is typically 60 Hz to 100 Hz, but can be adjusted via the command set. The ST7565R is also known for its low EMI emissions, as it uses a spread-spectrum oscillator in some versions. The COG assembly process requires a cleanroom environment to avoid contamination, and the driver IC die is often coated with a silicone gel to protect against moisture. The 3.18 inch display’s viewing angle is typically 6 o’clock or 12 o’clock, depending on the polarizer alignment, and the ST7565R supports a wide viewing angle through its voltage adjustment. The driver IC’s power consumption can be reduced by using the sleep mode, which drops current to less than 10 µA. The display module itself usually includes a backlight, which is separate from the driver IC, and the ST7565R does not control the backlight directly. The backlight is typically a white LED with a forward voltage of 3.0V to 3.4V and current of 20 mA to 60 mA. The driver IC’s temperature compensation feature is critical for outdoor applications, as it adjusts the LCD bias voltage to maintain contrast when the temperature changes. The compensation curve is stored in the driver IC’s internal registers, and you can program it for different LCD fluids. The ST7565R is also used in other sizes like 1.3 inch, 2.0 inch, and 2.7 inch, but the 3.18 inch variant is optimized for a larger viewing area. The driver IC’s pinout for the COG version is typically a 24-pin or 30-pin configuration, with the pins arranged in a single row on the glass. The connection to the external PCB is via a flexible flat cable (FFC) or a zebra strip, depending on the module design. The FFC has a pitch of 0.5 mm or 0.3 mm, and the number of pins is usually 12 to 18 for the interface. The driver IC’s data sheet specifies that the maximum clock frequency for the serial interface is 10 MHz, but in practice, many users run it at 4 MHz to 8 MHz to avoid signal integrity issues. The command set includes a display data write command that allows you to write 8 bits of data per clock cycle, but the SPI mode only sends 1 bit per clock, so the data rate is slower. For high-speed updates, the parallel interface is better, but it uses more pins. The ST7565R also supports a hardware scrolling feature, but it’s limited to vertical scrolling of the entire screen. The driver IC’s internal RAM is organized as 8 pages of 128 columns, with each page representing 8 rows of pixels. This means you can write data in 8-pixel vertical chunks, which is efficient for text rendering. The driver IC’s power-on reset circuit ensures that the display starts in a known state, but it’s still recommended to initialize the driver IC with a software reset sequence. The initialization sequence typically takes about 10 ms to 20 ms, including the power-up delay. The driver IC’s voltage generator uses a charge pump that requires external capacitors, usually 0.1 µF to 1 µF, which are mounted on the COG glass or the FPC. The charge pump efficiency is about 70% to 80%, so the input current increases when the LCD voltage is higher. The driver IC’s maximum output current for the LCD bias is about 0.5 mA, which is sufficient for a 128x64 display. The contrast ratio can be improved by using a higher bias voltage, but this increases power consumption and may reduce the lifetime of the LCD. The ST7565R also includes a built-in test mode for verifying the display’s functionality during manufacturing. The driver IC’s packaging is a bare die, which is why it’s used in COG modules. The die size is about 2.5 mm x 3.0 mm, with a thickness of 0.3 mm to 0.5 mm. The bonding pads are on the edge of the die, and they are connected to the glass via gold bumps or ACF. The COG process requires precise alignment, and the driver IC is often placed at the edge of the glass to allow for the FPC connection. The 3.18 inch display’s glass thickness is typically 0.55 mm to 0.7 mm, and the COG area adds about 0.2 mm to the overall thickness. The driver IC’s operating temperature range is -40°C to +85°C for the storage, but the LCD fluid limits the operating range to -20°C to +70°C. The driver IC’s ESD protection is rated at 2 kV for the human body model, but the COG module is more sensitive to ESD due to the exposed traces. The display module often includes a ground plane on the FPC to reduce ESD risk. The driver IC’s compatibility with the 3.18 inch display is also confirmed by the fact that many manufacturers like Winstar, Newhaven, and DisplayModule use the ST7565R for their 128x64 COG modules. The driver IC’s datasheet is available from Sitronix, but the part number may vary slightly depending on the vendor. The ST7565R is also second-sourced by other companies, but the pinout and command set are identical. The driver IC’s power consumption in the normal mode is about 0.5 mA to 1.5 mA, and in the sleep mode, it drops to 0.5 µA to 10 µA. The backlight adds 20 mA to 60 mA, so the total module power consumption is dominated by the backlight. The driver IC’s contrast adjustment is done via the electronic volume register, which changes the LCD bias voltage. The register has 64 steps, and each step corresponds to about 0.1V to 0.2V change. The default contrast value is usually set at the factory, but you can adjust it in software. The driver IC’s temperature compensation uses a lookup table that is stored in the internal ROM, but you can also write your own compensation values. The compensation range is typically -20°C to +70°C, with a resolution of 1°C. The driver IC’s internal oscillator frequency is trimmed during manufacturing, but it can vary by ±10% over temperature and voltage. The oscillator frequency affects the frame rate, so you may need to adjust the display timing if the frequency is too low or too high. The driver IC’s command set includes a “display all points” command for testing, which lights up all pixels. The driver IC also supports a “inverse display” mode, which swaps black and white pixels. The driver IC’s interface is 5V tolerant, so you can connect it directly to a 5V microcontroller without level shifting. The driver IC’s logic supply voltage is 2.7V to 5.5V, but the LCD drive voltage is generated internally. The driver IC’s maximum input voltage on the data lines is VDD + 0.3V, so you should avoid exceeding that. The driver IC’s output pins are open-drain, but they are used for the segment and common outputs. The segment outputs are 64 pins, and the common outputs are 8 pins, but the driver IC also has 4 extra segment outputs for the border. The driver IC’s output voltage for the segment pins is V0 to V0 - 5V, depending on the LCD bias. The driver IC’s output current for each segment is about 0.1 mA to 0.2 mA, which is enough to drive the LCD capacitance. The driver IC’s output impedance is about 5 kΩ to 10 kΩ, which limits the maximum frame rate. The driver IC’s internal charge pump requires external capacitors, typically 0.1 µF, 0.47 µF, and 1 µF, depending on the voltage level. The charge pump output voltage is adjustable via software, but the maximum voltage is limited by the driver IC’s design. The driver IC’s typical V0 voltage for a 3.18 inch display is 10V to 12V, which gives a good contrast. The driver IC’s power efficiency is about 70% to 80%, so the input power is about 1.5 times the output power. The driver IC’s operating current is about 0.5 mA to 1.5 mA, but it can spike to 5 mA during the charge pump startup. The driver IC’s startup time is about 10 ms to 20 ms, after which the display is ready. The driver IC’s reset pin is active low, and it should be held low for at least 1 µs to reset the driver IC. The driver IC’s command set includes a “read status” command, which returns the busy flag and the power status. The driver IC’s busy flag is high during the charge pump startup, so you should wait until it clears before sending commands. The driver IC’s maximum clock frequency for the serial interface is 10 MHz, but the actual throughput is lower due to the command overhead. The driver IC’s SPI mode uses a 8-bit command followed by an 8-bit data byte, so the effective data rate is about 5 MHz to 8 MHz. The driver IC’s parallel interface can achieve 20 MHz to 30 MHz, but it uses 8 data pins plus control pins. The driver IC’s interface is compatible with many microcontrollers, including Arduino, STM32, ESP32, and PIC. The driver IC’s library is available for many platforms, but you can also write your own driver. The driver IC’s initialization sequence is standard, but you may need to adjust the contrast and bias settings for the specific LCD. The driver IC’s bias setting is typically 1/9 for a 128x64 display, which means the LCD voltage is divided into 9 levels. The driver IC’s duty cycle is 1/64, which means each common line is active for 1/64 of the frame time. The driver IC’s frame rate is about 60 Hz to 100 Hz, which is enough for smooth animation. The driver IC’s response time is about 10 ms to 20 ms for the LCD, so the driver IC itself is not the bottleneck. The driver IC’s reliability is high, but the COG module is more fragile than a standard LCD module. The driver IC’s failure rate is less than 1% over 100,000 hours, based on industry data. The driver IC’s cost is about $1 to $2 per unit in volume, but the COG module costs more due to the assembly process. The driver IC’s availability is good, but it’s a mature part that is still in production. The driver IC’s future is uncertain, but there are newer parts like the ST7567 that are pin-compatible. The ST7567 is a lower-power version with a similar command set, but it’s not as widely used. The driver IC’s datasheet is available from Sitronix, but you can also find it on other sites. The driver IC’s application notes are useful for designing the interface and power supply. The driver IC’s typical circuit includes a resistor for the contrast adjustment, but the COG module usually has a fixed resistor. The driver IC’s voltage generator uses a charge pump that requires a capacitor between VOUT and VSS. The driver IC’s capacitor values are specified in the datasheet, but you can use 0.1 µF to 1 µF. The driver IC’s output voltage is adjustable via the electronic volume register, but the maximum voltage is limited by the charge pump. The driver IC’s temperature compensation is essential for outdoor use, as the contrast changes with temperature. The driver IC’s compensation curve is stored in the internal ROM, but you can also use external temperature sensors. The driver IC’s command set includes a “temperature compensation” command, which sets the compensation slope. The driver IC’s default compensation is set for a typical LCD fluid, but you can adjust it for your specific fluid. The driver IC’s power consumption is lower than older drivers like the KS0108, which used a separate controller. The driver IC’s COG package is smaller than the COB package, which uses a PCB. The driver IC’s COG module is thinner, lighter, and more reliable than the COB module. The driver IC’s COG module is also more expensive to manufacture, but the cost is offset by the smaller size. The driver IC’s COG module is used in many portable devices, such as glucose meters, thermometers, and handheld terminals. The driver IC’s interface is simple, but you need to be careful with the timing. The driver IC’s command set is well-documented, and you can find many examples online. The driver IC’s library for Arduino is available, but you can also use the LiquidCrystal library for character displays. The driver IC’s graphic library is available for many platforms, but you need to adapt it to the 128x64 resolution. The driver IC’s pixel addressing is done by page and column, which is different from the standard x,y coordinate system. The driver IC’s page address is from 0 to 7, and the column address is from 0 to 127. The driver IC’s data is written in 8-bit bytes, where each bit represents a pixel in the page. The driver IC’s write command is “0xB0” for page 0, and the column address is set by two commands: “0x10” for the high nibble and “0x00” for the low nibble. The driver IC’s read command is also available, but it’s not commonly used. The driver IC’s read command returns the data from the RAM, but it’s slower than the write command. The driver IC’s read command is useful for verifying the data, but it’s not necessary for most applications. The driver IC’s command set includes a “display start line” command, which sets the top row of the display. The driver IC’s start line is usually set to 0, but you can use it for scrolling. The driver IC’s scroll feature is limited to the entire screen, but you can also use the page address for partial scrolling. The driver IC’s power save mode is enabled by a command, which turns off the display and the charge pump. The driver IC’s power save mode reduces the current to less than 10 µA, but the RAM is still active. The driver IC’s power save mode is useful for battery-powered devices. The driver IC’s wake-up time is about 10 ms to 20 ms, which is acceptable for most applications. The driver IC’s display on/off command is “0xAF” for on and “0xAE” for off. The driver IC’s