MM74C923WMX

The MM74C923WMX is a CMOS key encoder from ON Semiconductor that provides comprehensive logic for encoding an array of SPST switches. It supports keyboard scanning via an external clock or capacitor and includes on-chip pull-up devices for switches up to 50 kΩ on resistance, eliminating the need for diodes to prevent ghost switches. The encoder features an internal debounce circuit requiring a single external capacitor, which can be omitted if not needed. A 'Data Available' output signals a valid keyboard entry, returning low when the key is released, even if another is pressed. It supports two-key roll-over and remembers the last key pressed. The 3-STATE outputs are LPTTL compatible, facilitating easy expansion and bus operation. This device is supplied in a 20-SOIC package suitable for surface mounting and operates within a wide supply voltage range of 3V to 15V, with an operating temperature range of -40°C to 85°C. Its low power consumption makes it suitable for various applications.

The MM74C923WMX encoder is designed for efficient switch matrix encoding. It offers features like on-chip row pull-up devices, keybounce elimination with a single capacitor, and a last-key register at the outputs. The 3-STATE outputs ensure compatibility with LPTTL and enable straightforward bus integration. The device is packaged in a 20-SOIC form factor, designed for surface mount applications. Key electrical characteristics include a supply voltage range of 3V to 15V and an operating temperature range of -40°C to 85°C. The encoder circuit is configured as 1 x 9:4, with one independent circuit.