STN LCD controller with 1024-byte on-chip font ROM


The SAP1024B is a dot-matrix STN LCD controller. It is designed to be used together with SEGMENT drivers, COMMON drivers, and Display data SRAM to build a complete display system for STN LCD modules.

The SAP1024B has on-chip font ROM. Each font is composed of 8 dots x 8 dots, and totally 128 fonts are available on-chip. The fonts are pre-defined during chip fabrication.

The SAP1024B has 16-bit address bus and necessary control bus to interface to an external Display Memory of up to 64K bytes. Text data, graphic data, or both can be freely allocated to the Display Memory. In addition to storing text data and graphic data, user-definable fonts can also be stored on the Display Memory. The maximum number of user-definable fonts is 256.

The SAP1024B has an 8-bit data bus and necessary control bus to interface to a host microcontroller. The host microcontroller, via the SAP1024B, can send commands to the SAP1024B, such that the SAP1024B can perform various display operation. User-definable fonts can also be written to the Display Memory via the SAP1024B. Many types of microcontrollers, such as 80C51 or Z80, can easily interface to the SAP1024B.

A wide variety of LCD panels are surpported. Both the number of characters in horizontal direction (columns) and the number of characters in vertical direction (lines) are hardware-programmable. Number of dots of a font in both the horizontal direction and vertical direction is also hardware-programmable. In addition, the actual number of displayed columns can be adjusted via software programming.


  • Display formats (pin-selectable)
    • Columns (SEGMENTS): 32, 40, 64, 80
    • Lines (COMMON): 2, 4, 6, 8, 10, 12, 14, 16, 20, 24, 28, 32
  • Character fonts (pin-selectable)
    • Horizontal dots: 5, 6, 7,8 (pin-selectable)
    • Vertical dots: 8 (fixed, that is, always 8 dots in the vertical direction)
  • Display duty: 1/16 to 1/128.
  • 128 on-chip fonts of 8-dots x 8-dots.
  • 64K-byte external Display Data Memory.
  • Memory space in the Display Data Memory for text area, graphic area and font generator area can be freely allocated via software programming of related registers.
  • 256 user-definable fonts on the external Display Data Memory.
  • On-chip crystal oscillator
  • Attribute functions for text: blinking, reverse display ..etc.
  • Logical OR, AND, and EXOR operation between text display and graphic display.
  • 1~8 raster (horizontal) scan lines for the cursor pattern.
  • 8-bit parallel interface with a host microcontroller.
  • Read/Write operation between the host microcontroller and the SAP1024B for status check, command, and data.
  • Operating voltage range: 2.7 ~ 5.5 volts.
  • Operating frequency: 5.5 MHz, when VDD=5 volts.
  • Operating temperature range: -20 to +70 °C
  • Storage temperature range: -55 to + 125 °C
  • ESD
    •  exceeding 4000 V( HBM EIA/JESD22-A114-B).
    •  exceeding 300 V (MM EIA/JESD22-A115-A).
  • Latch-up: >250 mA

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