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AT90S8535 - 8-Bit AVR Microcontroller

Overview

The AT90S8535 is a low-power CMOS 8-bit microcontroller based on the AVR® enhanced RISC architecture. It is part of the AT90S family, designed for high-performance and low-power embedded applications. By executing powerful instructions in a single clock cycle, the AT90S8535 achieves throughputs approaching 1 MIPS per MHz, allowing system designers to optimize power consumption versus processing speed.

This microcontroller is particularly suited for applications requiring moderate processing power with efficient energy usage, making it ideal for battery-operated devices, industrial control systems, and consumer electronics.

Key Features

AVR Enhanced RISC Architecture – High-performance, low-power RISC CPU with 118 powerful instructions, most executing in a single clock cycle.
In-System Programmable Flash Memory – 8KB of Flash memory for flexible firmware updates via SPI serial interface (1,000 write/erase cycles endurance).
EEPROM & SRAM – 512 bytes of EEPROM (100,000 write/erase cycles) and 512 bytes of internal SRAM for data storage.
Analog-to-Digital Converter (ADC) – 8-channel, 10-bit ADC for precision analog signal processing.
Programmable I/O – 32 general-purpose I/O lines for interfacing with external peripherals.
Serial Communication – Programmable Serial UART for asynchronous data transfer.
Timers & PWM – Two 8-bit timers, one 16-bit timer, and three PWM channels for timing and motor control applications.
Power Management – Three sleep modes (Idle, Power Save, Power Down) to minimize energy consumption.
Voltage Range – Operates at 4.0V–6.0V (standard) or 2.7V–6.0V (low-voltage variant).

Applications

The AT90S8535 is widely used in embedded systems requiring efficient processing and low power consumption. Common applications include:

Industrial Automation – Motor control, sensor interfacing, and process monitoring.
Consumer Electronics – Remote controls, smart home devices, and portable gadgets.
Automotive Systems – Dashboard controls, lighting systems, and basic ECU functions.
Medical Devices – Portable diagnostic equipment and wearable health monitors.
Embedded Control – Robotics, automation, and real-time control systems.

Electrical Characteristics

Operating Conditions

Supply Voltage (V_CC): 4.0V–6.0V (AT90S8535), 2.7V–6.0V (AT90LS8535).
Clock Speed: 0–8 MHz (AT90S8535), 0–4 MHz (AT90LS8535).
Power Consumption (Active Mode @ 4MHz, 5V): ~10mA (typical).
Power Consumption (Power-Down Mode): <1µA (typical).

Analog Characteristics

ADC Resolution: 10-bit.
ADC Channels: 8 multiplexed inputs.
Conversion Time: ~65µs at 8MHz clock.
Reference Voltage: External or internal (2.56V).

Timing Characteristics

CPU Clock Frequency: Up to 8MHz (AT90S8535), 4MHz (AT90LS8535).
PWM Frequency: Adjustable via prescaler (dependent on timer settings).
Watchdog Timer: Programmable from 16ms to 2s.

Package Information

The AT90S8535 is available in multiple package options, including:

PDIP (Plastic Dual In-Line Package) – 40-pin, through-hole mounting.
TQFP (Thin Quad Flat Package) – 44-pin, surface-mount variant.
PLCC (Plastic Leaded Chip Carrier) – 44-pin, J-lead package.

Pin Configuration (PDIP-40 Example)

V_CC, GND – Power supply and ground pins.
Port A (PA0-PA7) – 8-bit bidirectional I/O with ADC functionality.
Port B (PB0-PB7) – 8-bit bidirectional I/O with timer/PWM functions.
Port C (PC0-PC7) – 8-bit bidirectional I/O with UART support.
Port D (PD0-PD7) – 8-bit bidirectional I/O with interrupt capabilities.
RESET – Active-low reset input.
XTAL1/XTAL2 – Crystal oscillator connections.

Conclusion

The AT90S8535 is a versatile 8-bit microcontroller offering a balance of performance, power efficiency, and integration. Its rich feature set—including Flash memory, EEPROM, ADC, and multiple timers—makes it suitable for a wide range of embedded applications. With support for in-system programming and multiple power-saving modes, it is an excellent choice for cost-sensitive and energy-efficient designs.

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