The CH454 is a digital tube display driver and a keyboard scan control chip. CH454 built-in clock oscillation circuit, can dynamically drive 8 16-segment digital tubes or 128 LEDs, support 11 segments, 14 segments, 16 segments × 8 and 17 segments × 7; also can perform 64-key keyboard scanning; The CH454 exchanges data with a single-chip microcomputer or the like via a 2-wire serial interface.
2.1. Display driver
- Built-in current drive stage, segment current is not less than 20mA, word current is not less than 150mA.
- Dynamic display scan control, directly drive 8-bit 16-segment digital tube or 128 LED luminous tube.
- Each digital tube is digitally flashed independently, both fast and slow flicker speeds can be selected.
- 16 levels of brightness control are provided by the duty cycle setting.
- Partial segment addressing, independently controlling light and extinction of the first 64 LEDs or the first 8 segments of each digital tube.
- Scanning limit control, supports 1 to 8 digital tubes, and only allocates scan time for valid digital tubes.
- The word drive output polarity can be selected to facilitate external expansion of the drive voltage and current.
2.2. keyboard control
- Built-in 64-key keyboard controller based on 8×8 matrix keyboard scan.
- Built-in debounce circuit with pull-down resistor for built-in button status input.
- Keyboard interrupt output, active low.
- A button release flag is provided for querying the button to be pressed and released.
- Support button wake-up, CH454 in low power saving state can be awakened by partial button.
2.3. Other miscellaneous
- Two-wire serial interface, compatible with the I2C bus, saving pins.
- Built-in clock oscillating circuit, no need to provide external clock or external oscillating components, more anti-interference.
- Supports low-power sleep, saves power, can be woken up by a button or wake up by a command operation.
- Available in SOP-28 and SDIP32 lead-free packages, compatible with RoHS