The MC14489B is a flexible light-emitting-diode driver which directly interfaces
to individual lamps, 7-segment displays, or various combinations of both. LEOs wired with common cathodes are driven in a multiplexed-by-5 fashion. Communication with an MCUIMPU is established through a synchronous serial port. The MC 14489B features data retention plus decode and scan circuitry, thus relieving processor overhead. A single, current -setting resistor is the only ancillary component required.
A single device can drive anyone of the following: a 5-digit display plus decimals, a 4-112-digit display plus decimals and sign, or 25 lamps. A special technique allows driving 5 112 digits; see Figure 16. A configuration register
allows the drive capability to be partitioned off to suit many additional applications. The on-chip decoder outputs 7-segment-format numerals O to 9, hexadecimal characters A to F, plus 15 1etters and symbols.
The MC14489B is compatible with the NXP® SPI and National MI-CRO-WIRETM serial data ports. The chip's patented BitGrabberTM registers augment the serial interface by allowing random access without steering or
address bits. A 24-bit transfer updates the display register. Changing the configuration
register requires an 8-bit transfer.