What the DS80C323-QCD+ is and where it fits
The Maxim Integrated DS80C323-QCD+ is an 8-bit microcontroller built around the 8051 core, clocked at 18 MHz. It is a ROMless device — no on-chip program memory — so code resides in an external EPROM, Flash, or OTP memory accessed through the external bus interface. This makes it a fit for designs where the firmware is fixed at the factory or where a separate memory device is already on the board for other functions. The part integrates 256 x 8 bytes of internal RAM, 32 I/O lines, a power-fail reset, and a watchdog timer. Connectivity includes an external bus interface (EBI/EMI), a serial I/O (SIO), and a UART/USART. Packaged in a 44-lead PLCC with J-leads (44-PLCC, 16.59 x 16.59 mm body), it is intended for surface-mount assembly. The commercial temperature range of 0°C to 70°C limits it to indoor, controlled environments.
ROMless architecture — BOM implications
Because the DS80C323-QCD+ has no program memory on-chip, every design must budget for an external EPROM, Flash, or OTP memory. That adds a second IC, extra board area, and a separate programming step during manufacturing. The trade-off is flexibility: the external memory can be swapped for a different density or supplier without changing the MCU, and firmware updates can be handled by replacing the memory device — or, if using Flash, by in-system programming through the UART or SIO.
Lifecycle and sourcing posture
This reduces sourcing risk for new designs and ongoing production runs. Maxim Integrated (now part of Analog Devices) is the sole manufacturer for this part. There is no second-source listed in the available records, so the BOM carries single-source exposure on the MCU itself. The part is RoHS3 compliant.