ST72251 Microcontroller Unit

Overview

The ST72251 is an HCMOS-based microcontroller unit (MCU) designed for embedded control applications. It features an 8-bit architecture with advanced peripherals, making it suitable for a wide range of industrial and consumer applications. The device operates within a supply voltage range of 3V to 6V and supports a maximum CPU frequency of 8MHz (with a 16MHz oscillator). It is available in multiple package options, including SO28, SDIP32, and PSDIP32.

Key Attributes

• Program Memory: 4K or 8K bytes (depending on variant)
• RAM: 256 bytes (64 bytes stack)
• Operating Temperature: -40°C to +85°C
• Package Options: SO28, SDIP32, PSDIP32, CSDIP32W

Features

Core Features

• 8-bit ST7 CPU core with 16-bit addressing
• Multiple addressing modes for efficient programming
• Up to 8MHz CPU clock frequency
• Low-power consumption with multiple power-saving modes

Peripheral Features

• I/O Ports: Configurable bidirectional I/O pins with interrupt capability
• Watchdog Timer (WDG): Hardware watchdog for system reliability
• 16-bit Timer: Flexible timer with input capture and output compare
• I2C Bus Interface: Support for I2C communication protocol
• Serial Peripheral Interface (SPI): Full-duplex synchronous serial communication
• 8-bit ADC: Analog-to-digital converter with multiple input channels

System Features

• Clock system with multiple clock sources
• Reset mechanisms (external, power-on)
• Interrupt controller with multiple priority levels
• Power-saving modes (Slow, Wait, Halt)

Applications

The ST72251 is designed for a broad range of embedded control applications, including:

• Industrial control systems
• Consumer electronics
• Automotive subsystems
• Home automation
• Sensor interfacing and data acquisition
• Motor control

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (V_DD): -0.3V to +7V
• Input Voltage: -0.3V to V_DD+0.3V
• Operating Temperature: -40°C to +85°C
• Storage Temperature: -65°C to +150°C

Recommended Operating Conditions

• Supply Voltage (V_DD): 3.0V to 6.0V
• Operating Temperature: -40°C to +85°C
• CPU Frequency: Up to 8MHz

DC Characteristics

• Input High Voltage (V_IH): 0.7V_DD to V_DD
• Input Low Voltage (V_IL): 0 to 0.3V_DD
• Output High Voltage (V_OH): V_DD-0.5V (I_OH = -10mA)
• Output Low Voltage (V_OL): 0.5V (I_OL = 10mA)

Oscillator Characteristics

• External Crystal Frequency: 1MHz to 16MHz
• Start-up Time: Typically 10ms

ADC Characteristics

• Resolution: 8 bits
• Conversion Time: 10µs typical
• Input Voltage Range: 0V to V_DD

Package Information

Available Packages

• SO28: 28-pin Small Outline package (7.5mm width)
• SDIP32: 32-pin Shrink Dual In-line Package
• PSDIP32: 32-pin Plastic Shrink DIP
• CSDIP32W: 32-pin Ceramic Shrink DIP (Windowed for EPROM)

Mechanical Data

• SO28 Dimensions: 17.9mm x 7.5mm body, 1.27mm pitch
• SDIP32 Dimensions: 41.4mm x 13.97mm body, 2.54mm pitch
• Lead Material: Copper alloy
• Lead Finish: Matte tin or solder dipped

Memory Organization

Memory Map

• Program Memory: 4K or 8K bytes (Flash/EPROM)
• RAM: 256 bytes (including 64 bytes stack)
• Peripheral Registers: Mapped in specific address ranges
• EEPROM: Not available on this device

Development Support

The ST72251 is supported by a comprehensive development ecosystem including:

• ST7 assembler and C compiler
• In-circuit emulators
• Evaluation boards
• Programming tools for EPROM versions

Ordering Information