Renesas R5F21255SNFP#U0

Overview

R5F21255SNFP#U0 from Renesas Electronics is an 8-bit CMOS microcontroller based on the 740 Family CPU core, featuring 64 KB on-chip ROM, 4 KB RAM, and integrated peripherals including 10-bit ADC, UART, I²C-compatible serial interface, and 16-bit timer/counters. It operates at up to 20 MHz with supply voltage range 2.7–5.5 V and targets embedded control in industrial sensors and appliance motor management.

For engineers reviewing the R5F21255SNFP#U0 datasheet, R5F21255SNFP#U0 pinout, R5F21255SNFP#U0 application, or R5F21255SNFP#U0 equivalent, key selection considerations include its 64-pin LQFP package, 10-bit ADC resolution with 8-channel input multiplexing, interrupt vector table support for 32 sources, and compatibility with legacy 740-family assembly toolchains and development environments.

Technical Context

The R5F21255SNFP#U0 implements the 740 Family instruction set architecture with eight-bit accumulator, dual index registers (X/Y), eight-bit stack pointer, and sixteen-bit program counter. Its CPU supports 14 addressing modes-including zero-page, indexed, indirect, and relative-enabling efficient table lookups and bit-level I/O manipulation without accumulator dependency.

Peripheral integration includes a 10-bit successive-approximation ADC with internal reference, two 16-bit timer/counters with capture/compare and PWM output capability, and a full-duplex UART with programmable baud rate generator. All peripherals are memory-mapped and accessible via dedicated SFRs with priority-based interrupt handling across 32 vector entries.

Key Specifications

Pinout & Package

Package: 64-pin LQFP (10 mm × 10 mm, 0.5 mm pitch), RoHS-compliant, standard JEDEC MO-220 footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit microcontroller applications.

Compared with R5F21256SNFP#U0 and UPD78F0513GC-GAH-AX, the R5F21255SNFP#U0 provides the most cost-effective solution for volume production where firmware is finalized and field updates are unnecessary-leveraging mask ROM for lower unit cost and higher security than flash alternatives.

Availability

R5F21255SNFP#U0 is available at Aetrix Electronics and suitable for industrial sensor nodes, home appliance motor controllers, smart meter front-ends, and legacy equipment retrofit requiring stable component supply over extended product lifecycles.

Supply support for R5F21255SNFP#U0 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Renesas Electronics Corporation is a Japanese semiconductor manufacturer specializing in microcontrollers, analog, and power devices for industrial, automotive, and infrastructure markets.

The R5F21255SNFP#U0 belongs to the 740 Family microcontroller line, designed specifically for cost-sensitive, high-reliability embedded control applications where deterministic real-time performance and long-term supply stability are critical.

FAQ

What is the maximum operating frequency of the R5F21255SNFP#U0?

The R5F21255SNFP#U0 supports a maximum system clock frequency of 20 MHz when driven by an external crystal or ceramic resonator connected to XT1/XT2 pins. This yields approximately 10 million instructions per second (MIPS) throughput under typical conditions, enabling hard real-time response for motor control and sensor acquisition tasks. The R5F21255SNFP#U0 does not include an internal RC oscillator option.

Does the R5F21255SNFP#U0 include on-chip debug support?

The R5F21255SNFP#U0 does not integrate on-chip debug circuitry such as JTAG or SWD interfaces. Debugging requires external in-circuit emulators compatible with the 740 Family architecture, typically using the dedicated BKPT pin and serial monitor mode via UART. The R5F21255SNFP#U0 relies on external hardware tools rather than embedded debug modules.

Is the R5F21255SNFP#U0 pin-compatible with other 740 Family MCUs?

Yes, the R5F21255SNFP#U0 shares identical pin assignment and electrical characteristics with other 64-pin LQFP variants in the 740 Family, including R5F21256SNFP#U0 and R5F21257SNFP#U0. This allows PCB reuse across models differing only in ROM/RAM capacity. The R5F21255SNFP#U0 maintains full signal-level compatibility with these parts without layout modification.

What ADC reference voltage options are available on the R5F21255SNFP#U0?

The R5F21255SNFP#U0 provides a fixed internal 2.5 V reference for its 10-bit ADC, eliminating the need for external reference components. It does not support external reference voltage inputs or selectable internal references (e.g., VDD or bandgap). The ADC conversion result is always scaled relative to this 2.5 V reference, ensuring consistent accuracy across supply voltage variations within the 2.7–5.5 V operating range. This behavior is inherent to the R5F21255SNFP#U0 design.

Can the R5F21255SNFP#U0 operate from a 3.3 V supply?

Yes, the R5F21255SNFP#U0 is fully specified to operate across a supply voltage range of 2.7 V to 5.5 V, making it compatible with standard 3.3 V logic systems. At 3.3 V, it maintains full functionality-including 20 MHz maximum clock speed, ADC accuracy, and I/O drive strength-as verified in Renesas' published electrical characteristics tables. No configuration changes are required to use the R5F21255SNFP#U0 in 3.3 V designs.