The CH452 is a digital tube display driver and a keyboard scan control chip.CH452 has built-in clock oscillator circuit, which can dynamically drive 8-digit digital tube or 64 LED tubes, with BCD decoding, flickering, shifting, segment addressing, beam decoding etc. It can also perform 64-key keyboard scanning; The CH452 exchanges data with a single-chip microcomputer through a 4-wire serial interface or a 2-wire serial interface that can be cascaded; and can provide a power-on reset signal to single chip microcomputer.
2.1. Display driver
- Built-in current drive stage, segment current is not less than 20mA, word current is not less than 100mA.
- Dynamic display scanning control, direct drive 8-digit digital tube or 64 LED Luminous tubes or 64-level beam.
- The segment of the digital tube and data bit can be chosen as no decoding mode or BCD decoding mode.
- BCD decoding supports a custom BCD code for displaying a special character.
- Left shift, right shift, left loop, right loop of the digital tube word data.
- Each digital tube is digitally flashed independently, both fast and slow flicker speeds can be selected.
- Arbitrary segment addressing, independently controlling the on and off of each LED or each segment of each digital tube.
- 64-level beam decoding, the column value is displayed by a light column consisting of 64 LEDs.
- Scanning limit control, supports 1 to 8 digital tubes, and only allocates scan time for valid digital tubes.
- 16 levels of brightness control are provided by the duty cycle setting.
- 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, you can choose low-level active output or low-level pulse output.
- A button release flag is provided for querying the button to be pressed and released.
- Support button wake-up, CH452 in low power saving state can be awakened by partial button.
2.3. External interface
- The same chip, a high-speed 4-wire serial interface or an economical 2-wire serial interface can be chosen.
- 4-wire serial interface: Supports multiple chip cascades, clock speeds from 0 to 2MHz, compatible with CH451 chips.
- 4-wire serial interface: DIN and DCLK signal lines can be shared with other interface circuits, saving pins.
- 2-wire serial interface: Supports two CH452 chips in parallel (the respective addresses are set by the ADDR pin level).
- 2-wire serial interface: 400KHz clock speed, compatible with two-wire I2C bus, saving pins.
- Built-in power-on reset which provides an active-high and active-low reset output for the single chip microcomputer.
2.4. Other miscellaneous
- 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.
- Support 3V~5V voltage.
- Available in SOP28 and DIP24S lead-free packages, compatible with RoHS, pins are compatible with the CH451 chip.