onsemi LC75805PES-3H LCD Driver IC: Datasheet, Pinout, and Application Circuit Guide
The onsemi LC75805PES-3H is a versatile and highly integrated LCD driver IC designed for controlling dot matrix graphic displays in a wide range of consumer and industrial applications. This chip is particularly common in automotive dashboards, home appliance control panels, and various instrumentation systems where a custom graphical interface is required. Its ability to drive a significant number of segments directly reduces the need for additional components, simplifying design and lowering overall system cost.
This guide provides a detailed overview of its key specifications, pin configuration, and a fundamental application circuit.
Datasheet Overview and Key Specifications
The datasheet for the LC75805PES-3H is the primary source for absolute maximum ratings, electrical characteristics, and detailed timing diagrams. Key specifications that define its operation include:
Display Outputs: This driver can control up to 65 segments and 8 common outputs. This configuration allows it to drive a 65 x 8 dot matrix LCD panel, providing substantial flexibility for displaying numbers, letters, symbols, and simple graphics.
Serial Data Interface: It features a versatile serial data input (SI) and clock input (CLK) interface for communication with a host microcontroller (MCU). This serial protocol minimizes the number of I/O pins required on the MCU, making it efficient to control.
Internal Display RAM: The IC includes an internal static display RAM that stores the data to be shown on the LCD. The MCU writes to this RAM via the serial interface, and the driver continuously scans and outputs the data to the display.
Built-in LCD Bias Circuit: A significant feature is its internal resistor ladder network that generates the intermediate bias voltages (V1-V4) required for driving the LCD. This eliminates the need for external resistors to create these voltages, saving board space and simplifying the design.
Operating Voltage: The device typically operates from a 2.7V to 6.0V power supply, making it suitable for both 3.3V and 5V systems.
Low Power Consumption: It supports low-power modes, which are crucial for battery-powered or energy-sensitive applications.
Pinout Description
The LC75805PES-3H is available in various packages; a common one is the 80-pin QFP. While a full pinout is in the datasheet, the pins can be categorized by function:
Power Supply (VDD, VSS): Pins for the positive supply voltage and ground.
LCD Bias Voltage (VLCD, V1-V4): VLCD is the input for the LCD operating voltage. V1 through V4 are the outputs from the internal bias generator.
Serial Interface (SI, CLK, CS): Serial Input (SI), Clock (CLK), and Chip Select (CS) pins for receiving data and commands from the microcontroller.
Common Outputs (COM0 - COM7): Eight outputs that drive the common lines of the LCD.
Segment Outputs (SEG0 - SEG64): Sixty-five outputs that drive the segment lines of the LCD.
Oscillator (OSC): A pin for connecting an external resistor to set the internal clock frequency for LCD driving.
Application Circuit Guide
A typical application circuit for the LC75805PES-3H involves connecting it to a host microcontroller and an LCD panel. The basic connections are outlined below:
1. Microcontroller Interface: Connect the MCU's GPIO pins to the driver's CS, CLK, and SI lines. The MCU will serially transmit display data following the timing protocol specified in the datasheet.
2. Power Decoupling: Place a 100nF ceramic decoupling capacitor close to the VDD and VSS pins to filter high-frequency noise.
3. LCD Bias Setup: Connect a potentiometer or a fixed resistor divider between VDD and VSS to provide an adjustable voltage to the VLCD pin. This controls the contrast of the LCD display. The internal bias generator will then output the required mid-level voltages (V1-V4) for the LCD.
4. Oscillator Setting: Connect an external resistor (Rosc) between the OSC pin and VSS to set the internal oscillation frequency, which determines the LCD frame rate.
5. LCD Panel Connection: Directly connect the common (COM0-COM7) and segment (SEG0-SEG64) outputs from the driver to the corresponding pins of the LCD glass.
The onsemi LC75805PES-3H is a highly capable and efficient solution for driving medium-sized graphic LCDs. Its integrated bias generation and serial interface make it a preferred choice for designers seeking to minimize external component count and simplify firmware control. When selecting this driver, carefully review the datasheet for timing requirements and absolute maximum ratings to ensure reliable operation in your specific application.
Keywords:
1. LCD Driver IC
2. Serial Data Interface
3. Dot Matrix Display
4. Segment/Common Outputs
5. Internal Bias Generator
