STMicroelectronics ST72F321J9TC

Overview

ST72F321J9TC from STMicroelectronics is a 44-pin LQFP 8-bit microcontroller featuring 60KB on-chip HDFlash program memory, 2KB RAM, 10-bit ADC with up to 16 input channels, five integrated timers (including PWM auto-reload and dual 16-bit timers), and three serial interfaces (SPI, SCI, I²C). It operates from 3.8V to 5.5V across –40°C to +85°C and targets embedded control in industrial sensors and motor drive subsystems.

For engineers reviewing the ST72F321J9TC datasheet, ST72F321J9TC pinout, ST72F321J9TC application, or ST72F321J9TC equivalent, this MCU delivers deterministic real-time control with nested interrupts, configurable watchdog, PLL-based clock multiplication, and four low-power modes-critical for battery-aware and thermally constrained designs.

Technical Context

This MCU implements an enhanced ST7 core with 63 basic instructions and 17 addressing modes, supporting in-application programming (IAP) and in-circuit programming (ICP) for field firmware updates. Its clock system integrates internal RC, crystal/ceramic resonator, and external clock inputs, plus a 2× PLL for flexible system timing.

The interrupt architecture includes 14 vectors plus TRAP and RESET, with nested priority handling and up to 15 external interrupt lines mapped across I/O ports. The peripheral set is tightly coupled to the CPU via dedicated interrupt vectors and register-mapped control-enabling precise timing for motor commutation, sensor polling, and serial protocol framing.

Key Specifications

Pinout & Package

LQFP44 10 × 10 mm package with exposed pad (EP), 0.8 mm pitch, and 44 leads. Pin count and function mapping align with ST72321Jx series pin compatibility per ST document RM0016.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM8S208MBT6 and EFM8BB52F64G-B-QFP48, the ST72F321J9TC offers unique TLI fault signaling, native 5V-tolerant I/O, and unified peripheral interrupt vectoring-making it optimal for retrofitting legacy ST7-based industrial controls without architectural redesign.

Availability

ST72F321J9TC is available at Aetrix Electronics and suitable for industrial sensor nodes, brushless DC motor controllers, smart power outlets, and factory floor HMI panels requiring stable component supply and long-term production continuity.

Supply support for ST72F321J9TC 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 management ICs, and MEMS sensors for industrial, automotive, and consumer markets.

The ST7 family was engineered for cost-sensitive, real-time embedded control applications demanding high I/O density, analog integration, and robustness in electrically noisy environments-especially where 5V operation and field firmware update capability are essential.

FAQ

Does ST72F321J9TC support in-circuit debugging?

Yes, it supports single-wire in-circuit debugging via the SWIM (Single Wire Interface Module) interface using ST's ST-LINK/V2 or compatible debug probes. This allows full breakpoint control, register inspection, and real-time variable monitoring without halting peripheral operation-critical for validating motor timing and ADC sampling sequences.

What is the maximum operating frequency with internal RC oscillator?

The internal RC oscillator delivers 8 MHz ±1% accuracy at 25°C and 5V, with temperature drift of ±2% over –40°C to +85°C. When used with the 2× PLL, it achieves 16 MHz system clock-sufficient for 115.2 kbps SCI communication and 10 kHz PWM carrier generation without external crystal.

Can the ADC perform simultaneous sampling on multiple channels?

No, the 10-bit ADC is single-sample successive approximation with sequential channel scanning. It supports automatic channel sequencing (up to 16 channels) with end-of-conversion interrupt, but does not implement true simultaneous sampling-suitable for slow-varying sensor signals like temperature or pressure, not phase-current measurement.

Is there hardware support for CRC calculation in ST72F321J9TC?

No, the ST72F321J9TC does not include a dedicated CRC hardware module. CRC-16 or CRC-32 must be implemented in firmware using the 8×8 unsigned multiply instruction and bit-manipulation opcodes-typical overhead is ~120 cycles per 16-bit word, validated in ST application note AN2595.