20 MHz 8051 core in a PLCC-44 — BOM-fit for industrial control
The Microchip AT89LP51IC2-20JU is an 8-bit microcontroller built around the 8051 core, clocked at 20 MHz. It carries 32 KB of on-chip Flash program memory and 1.375 KB of SRAM, with 40 general-purpose I/O lines brought out to a 44-lead PLCC package with J-leads.
The 32 KB Flash is sized for mid-complexity control firmware — a Modbus RTU stack, a PID loop with logging, or a small RTOS kernel fit without external memory. The 1.375 KB SRAM is tight; data buffers for communication or ADC samples need careful budgeting. On-chip peripherals include a brown-out detect, power-on reset, PWM outputs, and a watchdog timer — all standard for motor-drive and industrial-sensor applications. Connectivity covers I²C, SPI, and UART/USART plus an external bus interface for memory expansion. The 7-channel 10-bit ADC handles analog inputs like thermistor temperature, potentiometer feedback, or current-sense voltage without an external converter. The internal oscillator eliminates the external crystal for cost-sensitive builds, though an external clock source can be used when timing accuracy matters.
PLCC-44 footprint and layout notes
The 44-PLCC package (16.6 mm x 16.6 mm body) uses J-leads on a 1.27 mm pitch — a through-hole-like footprint that is socketable for prototyping but soldered directly in production. The J-lead form factor is more forgiving of board flex than a QFP, and the 1.27 mm pitch routes easily on two-layer boards. The centre pad is not an exposed thermal slug; heat dissipation relies on the leads and the copper area under the package.
No end-of-life notification or last-time-buy window has been issued for this series.