STMicroelectronics ST72F321R6T6

Overview

ST72F321R6T6 from STMicroelectronics is an 8-bit Flash microcontroller in LQFP64 (14 × 14 mm) package, featuring 32 KB on-chip HDFlash, 1 KB RAM, 10-bit ADC with 16 input channels, 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 targets industrial control panels requiring deterministic real-time response, low-power sensor node firmware, and embedded HMI subsystems.

For engineers reviewing the ST72F321R6T6 datasheet, ST72F321R6T6 pinout, ST72F321R6T6 application, or ST72F321R6T6 equivalent, this MCU delivers verified in-application programming (IAP), nested interrupt handling with 14 vectors, PLL-based clock multiplication, four power-saving modes (Halt/Active-Halt/Wait/Slow), and high-sink I/O capability-critical for direct LED driving and relay interface design.

Technical Context

The ST72F321R6T6 implements the ST7 core with 63 basic instructions and 17 addressing modes, supporting 8 × 8 unsigned multiply. Its clock system integrates crystal/resonator oscillators, internal RC oscillator, external clock bypass, and a 2× PLL for frequency scaling-enabling precise timing control in motor control loops and communication baud rate generation.

Interrupt management uses a nested controller with Top-Level Interrupt (TLI) support on 64-pin variants and 15 external interrupt lines mapped across four vectors. Peripheral integration includes a configurable watchdog timer, main clock controller with RTC/beeper, and dedicated hardware for SPI frame synchronization, SCI framing/parity, and I²C multimaster arbitration-all accessible via memory-mapped registers.

Key Specifications

Pinout & Package

LQFP64 (14 × 14 mm, 0.5 mm pitch) package with exposed thermal pad; RoHS-compliant, moisture-sensitive level 3.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM8S105K4T6 and EFM8BB52F16G-A-QFP64, the ST72F321R6T6 uniquely combines TLI support, true I²C multimaster capability, and verified IAP over SCI-making it optimal for legacy industrial designs requiring deterministic fault response and field-upgradable firmware without toolchain migration.

Availability

ST72F321R6T6 is available at Aetrix Electronics and suitable for industrial motor control, smart sensor nodes, human-machine interface (HMI) panels, and power supply monitoring systems requiring stable component supply and long-term production continuity.

Supply support for ST72F321R6T6 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-sensitive, real-time embedded control applications demanding high I/O count, robust peripheral integration, and field-programmable Flash-targeting industrial automation, appliance control, and building management systems.

FAQ

Does ST72F321R6T6 support in-circuit programming (ICP) via its standard pins?

Yes. The ST72F321R6T6 supports In-Circuit Programming through the SCI interface using the standard UART pins (TX/RX) and RESET pin, without requiring dedicated debug headers. This enables factory programming and field reprogramming using ST's STVP software and compatible UART-to-USB adapters, provided the BOOT bit is set during reset entry.

What is the maximum ADC sampling rate achievable with the 10-bit converter?

The ADC achieves a maximum conversion rate of 125 kSPS under typical conditions (VDD = 5 V, f_ADC = 1 MHz). Each conversion requires 13 clock cycles, and the sample-and-hold is internally synchronized to the ADC clock-enabling accurate measurement of signals up to ~40 kHz bandwidth with proper anti-aliasing filtering.

Can the PWM auto-reload timer generate complementary outputs with dead-time insertion?

No. The 8-bit PWM auto-reload timer (ART) supports four independent PWM outputs but lacks hardware dead-time generation or complementary pair control. Dead-time must be implemented in firmware using timer compare interrupts and GPIO toggling, limiting minimum controllable dead-time to ~2 µs at 16 MHz system clock.

Is the LQFP64 package of ST72F321R6T6 lead-free and RoHS compliant?

Yes. The ST72F321R6T6 in LQFP64 (14 × 14 mm) package is manufactured with lead-free terminations and fully complies with EU RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006, with homogeneous material declarations available upon request from STMicroelectronics.