25 MHz CPU and 7x24-bit sigma-delta ADC — what they mean for the design
The 25 MHz core speed is typical for the MSP430F6xx family and provides enough throughput to run a real-time energy-calculation algorithm (e.g., active/reactive power, RMS, THD) while servicing the seven sigma-delta ADCs in parallel. The 24-bit resolution on each converter gives the dynamic range needed to measure current from milliamps to hundreds of amps with a single shunt or CT — no gain-switching or external PGA required. For a polyphase meter, that means one MSP430F6775AIPEU handles all three phases plus neutral with one converter to spare for diagnostics or tamper detection.
Connectivity and I/O
With 90 I/O lines and a connectivity set that includes I2C, SPI, UART/USART, IrDA, and LINbus, this MCU can talk to an external communications module (PLC modem, Wi-Fi, LoRa) over UART, drive a segmented LCD directly from the on-chip LCD controller, and sample analog inputs through the 8-channel 10-bit auxiliary ADC for less critical measurements. The 128-LQFP package (20x14 mm body) is a standard footprint for this pin count — layout guides from TI's application notes for the MSP430F6xx metering EVM are a good reference for the analog front-end routing around the sigma-delta converters.