1. Overview & Purpose

️· What it is: The AS1120 is a driver chip designed to control static LCD (Liquid Crystal Display) panels. It's used when a microcontroller (or other system) needs to send data to drive individual segments of the display.
️· Key Feature: Allows a microcontroller to control 46 separate segments of an LCD with a relatively small number of pins.

2. Pinout & Key Functions

️· Package: 64-Pin PQFP (Plastic Quad Flat Package)
️· Critical Pins & Their Roles:

- DATAIN: Serial data input from the microcontroller.
- CLKIN: Clock signal, synchronizes data transfer.
- LOAD: Signal to transfer data from the shift register (inside the chip) to the LCD driver circuitry.
- BPLIN: Backplane input (the main voltage applied to the LCD segments).
- BPLOUT: Backplane output (regenerated backplane signal, can be used to drive another chip).
- RESETN: Reset input. Active-low (meaning you need to pull it LOW to reset the chip).
- VSS: Ground (0V).
- VDD: Positive power supply voltage.
- LCD0 - LCD41: Individual output pins that control the voltage applied to each segment of the LCD.
- TEST: Test pin, must be tied to VDD.

3. How it Works – Simplified

1. Serial Data: The microcontroller sends data *one bit at a time* to the AS1120 via DATAIN, synchronized by the clock signal on CLKIN. This data is stored in a "shift register" within the AS1120.
2. Loading the Data: Once all the data for a frame is in the shift register, the microcontroller asserts the LOAD signal. This transfers the data from the shift register to the LCD driver circuitry.
3. Displaying: The AS1120 applies the data to the individual LCD segments, creating the desired pattern on the display.
4. Backplane: The BPLIN and BPLOUT pins are important for the voltage applied across the LCD, which influences how the liquid crystals are aligned and how the display appears.

4. Operating Modes

️· Internal Oscillator (Clock Generation): The chip can generate its own clock if the OSC pin is left unconnected.
️· External Clock: An external clock signal can be supplied to CLKIN.
️· Cascading (Multiple Chips): Multiple AS1120 chips can be connected in series to control larger displays. DATAOUT on one chip connects to DATAIN on the next.
️· Backplane Regeneration: BPLOUT can be used to drive another AS1120 in a chain.

5. Key Technical Specifications (Important for Design)

️· Supply Voltage (VDD): Specify voltage requirement
️· Segment Voltage Levels: Understand the voltage levels the chip can apply to the LCD segments.
️· Clock Frequency: Maximum clock frequency allowed for reliable operation.
️· Temperature Range: Specify temperature tolerance

6. Ordering Information

️· Part Number: AS1120
️· Package: PQFP44
️· Delivery Form: Tape and Reel (standard for automated assembly)