MC14489

The MC14489 is a flexible lightemittingdiode driver which directly interfaces to individual lamps, 7segment displays, or various combinations of both. LEDs wired with common cathodes are driven in a multiplexedby5 fashion. Communication with an MCU/MPU is established through a synchronous serial port. The MC14489 features data retention plus decode and scan circuitry, thus relieving processor overhead. A single, currentsetting resistor is the only ancillary component required.

MC14489 can drive any one of the following: a 5digit display plus decimals, a 41/2digit display plus decimals and sign, or 25 lamps. A special technique allows driving 5 1/2 digits; see Figure 16. A configuration register allows the drive capability to be partitioned off to suit many additional applications. The onchip decoder outputs 7segmentformat numerals 0 to 9, hexadecimal characters A to F, plus 15 letters and symbols.

The MC14489 is compatible with the Motorola SPI and National MICROWIRE E serial data ports. The chip's patented BitGrabberE registers augment the serial interface by allowing random access without steering or address bits. A 24bit transfer updates the display register. Changing the configuration register requires an 8bit transfer.