STMicroelectronics ST72F321AR6T6

Overview

ST72F321AR6T6 from STMicroelectronics is an 8-bit microcontroller with 32 KB Flash memory, 1024-byte RAM, 10-bit ADC (16-channel), five timers including PWM auto-reload and dual 16-bit timers, and three serial interfaces (SPI, SCI, I²C). It operates from 3.8–5.5 V across –40 to +85°C and uses LQFP64 10×10 mm package for industrial motor control and sensor interface applications.

For engineers reviewing the ST72F321AR6T6 datasheet, ST72F321AR6T6 pinout, ST72F321AR6T6 application, or ST72F321AR6T6 equivalent, this MCU delivers deterministic real-time control with nested interrupts, in-application programming, PLL-based clock multiplication, and four low-power modes-critical for battery-aware embedded systems and automotive body electronics.

Technical Context

This MCU implements a Harvard architecture with 63 basic instructions and 17 addressing modes, supporting 8×8 unsigned multiply. Its interrupt system features 14 vectors plus TRAP/RESET and Top-Level Interrupt (TLI) on 64-pin variants, enabling prioritized response to external events and peripheral triggers.

The clock subsystem integrates crystal/ceramic resonator oscillators, internal RC oscillator, bypass mode for external clocks, and a 2× PLL multiplier. Power management includes enhanced low-voltage detector (LVD), auxiliary voltage detector (AVD), and four power-saving modes: Halt, Active-Halt, Wait, and Slow-each preserving specific register states and peripheral readiness.

Key Specifications

Pinout & Package

LQFP64 10×10 mm package with exposed thermal pad (RoHS-compliant); 64-pin configuration supports full I/O multiplexing, including 48 bidirectional I/O lines, 16 high-sink outputs, and dedicated pins for reset, clock, debug, and peripheral functions.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM8S105K4T6C and EFM8BB52F32G-C-QFP64, the ST72F321AR6T6 offers superior interrupt determinism via TLI and lower system-level power in Wait mode, making it optimal for time-critical, cost-sensitive industrial controls where legacy ST7 ecosystem compatibility matters.

Availability

ST72F321AR6T6 is available at Aetrix Electronics and suitable for industrial motor control, automotive body electronics, smart sensor nodes, and home appliance control requiring stable component supply across long production lifecycles.

Supply support for ST72F321AR6T6 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, power devices, sensors, and analog ICs for industrial, automotive, and consumer markets.

The ST7 family was engineered for cost-effective, deterministic real-time control in resource-constrained embedded systems-prioritizing interrupt responsiveness, low-voltage robustness, and in-system programmability over raw throughput.

FAQ

Does ST72F321AR6T6 support in-circuit debugging?

Yes, it supports single-wire in-circuit debugging via the SWIM (Single Wire Interface Module) protocol using the SWIM pin. This allows full breakpoint control, register inspection, and memory access without halting peripheral operation-enabling real-time validation of motor control loops and communication stacks.

What is the maximum operating frequency of the ST72F321AR6T6?

The maximum CPU clock frequency is 8 MHz, achieved using the internal PLL with 2× multiplication of a 4 MHz external crystal or internal RC oscillator. The PLL lock time is specified at 100 µs, and the system clock remains stable across the full –40°C to +85°C temperature range.

Can the ADC operate during low-power modes?

Yes, the 10-bit ADC can perform conversions in Wait and Active-Halt modes using the internal RC oscillator or external clock source. Conversion results trigger interrupts without waking the CPU core, enabling autonomous sensor monitoring with sub-10 µA average current draw per measurement cycle.

Is read-out protection reversible on the Flash memory?

No, read-out protection (ROP) is irreversible once enabled. When ROP Level 1 is activated, Flash contents become inaccessible via SWIM or ICP, and the only way to clear protection is a full Flash erase-which also deletes all user code and configuration bits. This ensures secure IP protection in production units.