The MAX6850 compact vacuum-fluorescent display (VFD) controller provides microprocessors with the multiplex timing for 7-segment, 14-segment, or 16-segment alphanumeric VFD displays up to 96 characters and controls industry-standard, shift-register, high-voltage grid/anode VFD tube drivers. The device supports display tubes using either one or two digits per grid, as well as universal displays. Hardware is included to simplify the generation of cathode bias and filament supplies and to provide up to five logic outputs, including a buzzer driver. The MAX6850 provides an internal crosspoint switch to match any tube-driver shift-register grid/anode order, and is compatible with both chip-in-glass and external tube drivers.
The MAX6850 includes an ASCII 104-character font, multiplex scan circuitry, and static RAM that stores digit, cursor, and annunciator data, as well as font data for 24 user-definable characters. The display intensity can be adjusted by an internal 16-step digital brightness control. The device also includes separate annunciator and cursor control with automatic blinking, as well as a low-power shutdown mode.
The MAX6850 provides timing to generate the PWM waveforms to drive the tube filament from a DC supply. The filament drive is synchronized to the display multiplexing to eliminate beat artifacts. The MAX6850 is compatible with SPI and QSPI.
For a 2-wire interfaced version, refer to the MAX6851