MICROCHIP MM5451YN

The MM5450 and MM5451 LED display drivers are monolithic MOS IC’s fabricated in an N-Channel, metal-gate process. The technology produces low-threshold, enhancement-mode, and ion-implanted depletion-mode devices. A single pin controls the LED display brightness by setting a reference current through a variable resistor connected to the supply. The MM5450 and MM5451 are designed to drive either 4- or 5-digit alphanumeric LED displays with the added benefit of requiring minimal interface with the display or data source. Data is transferred serially via two signals: clock and serial data. Data transfer without the added inconvenience of an external load signal is accomplished by using a format of a leading “1” followed by the allowed 35 data bits. These 35 data bits are latched after the 36th has been transferred. This scheme provides non-multiplexed, direct drive to the LED display. Characters currently displayed (thus, data output) changes only if the serial data bits differ from those previously transferred. Control of the output current for LED displays provides for the display brightness. To prevent oscillations, a 1 nF capacitor should be connected to pin 19, brightness control. There is an external reset connection shown which is available on unpackaged (die) only. When the chip first powers ON, an internal power ON reset signal is generated that resets all registers and all latches. The START bit and the first clock return the chip to its normal operation.

• Continuous Brightness Control
• Serial Data Input
• No Load Signal Requirement
• Enable (MM5450 Only)
• Wide Power Supply Operation
• TTL Compatibility
• 34 or 35 Outputs, 15 mA Capability
• Alphanumeric Capability

• Industrial Control Indicator
• Relay Driver
• Digital Clock, Thermometer, Counter, Voltmeter
• Instrumentation Readouts