4 MHz COP8 core — 4 KB OTP, 23 I/O, 6x12-bit ADC
The National Semiconductor COP8ACC728M9-XE is an 8-bit microcontroller from the COP8™ 8 A series, built around the COP8 core running at 4 MHz. It carries 4 KB of one-time-programmable (OTP) program memory — firmware is locked at the factory, with no field-update path. On-chip peripherals include 23 general-purpose I/O lines, a 6-channel 12-bit ADC, PWM and watchdog timer, plus a Microwire/Plus (SPI) serial interface.
OTP memory — no firmware changes after programming
The 4 KB OTP program memory means the code image is permanent once the device is programmed. This is a deliberate choice for high-volume, cost-sensitive designs where the application is finalised before production ramp. It also means the BOM line is tied to the original firmware — no software patches, no field upgrades. For development or prototyping, an EPROM or Flash-based sibling in the COP8 family is the practical alternative.
Commercial temperature range — indoor, controlled environments
It is not specified for automotive under-hood, outdoor telecom cabinets, or industrial motor drives where extended-temperature or AEC-Q100 qualification would be required.
For an OTP device that has been in the market for many years, active status is a positive signal — no last-time-buy clock is running.