Description
The MC14489B is a flexible light-emitting-diode driver which directly interfaces to individual lamps,7-segment displays, or various combinations of both. LEDs wired with common cathodes are driven in a multiplexed-by-5 fashion. Communication with an MCU/MPU is established through a synchro-nous serial port. The MC14489B 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 any one of the following:a 5-digit display plus decimals,a 4-1/2-digit 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 on-chip decoder outputs 7-segment-format numerals 0 to 9, hexadecimal characters A to F, plus 15 letters and symbols.
The MC14489B is compatible with the Motorola SPI and National MlCRO-WIRE TM 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.
Features
· Operating Voltage Range of Drive Circuitry:4.5 to 5.5V
· Operating Junction Temperature Range:-40° to 130℃
· Current Sources Controlled by Single Resistor Provide Anode Drive
· Low-Resistance FET Switches Provide Direct Common Cathode Interface
· Low-Power Mode(Extinguishes the LEDs) and Brightness Controlled via Serial Port
· Special Circuitry Minimizes EMI when Display is Driven and Eliminates EMl in Low-Power Mode
· Power-On Reset(POR) Blanks the Display on Power-Up, Independent of Supply Ramp Up Time
· May Be Used with Double-Heterojunction LEDs for Optimum Efficiency
· Chip Complexity:4300 Elements(FETs, Resistors, Capacitors, etc.)
(Picture: Pinout)
