AVR32DA28-I/SO - 8-bit AVR DA MCU, 32KB Flash, 28-SOIC | Microchip
MPN: AVR32DA28-I/SO ✓ ActiveAVR32DA28-I/SO Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, non-volatile program memory (Flash), working memory (SRAM), EEPROM, and a rich set of peripherals. The AVR® CPU belongs to a RISC architecture family known for deterministic instruction timing, single-cycle register access, and a mature toolchain (MPLAB X, Atmel Studio, and the Arduino-compatible DxCore core). In the broader taxonomy: AVR® DA -> 8-bit MCU -> microcontroller -> embedded processor -> semiconductor. The 1.8V to 5.5V supply range means the device can run directly from a single Li-ion cell or a regulated 3.3V / 5V rail, simplifying power-tree design.
Key features include the hardware multiplier for fast arithmetic, an Event System for inter-peripheral signalling without CPU intervention, intelligent analog peripherals (12-bit ADC, three comparators, three zero-cross detectors, a DAC), capacitive touch (PTC) hardware, six U(S)ARTs, two SPI, and TWI (I²C-compatible). The 28-SOIC (I/SO) variant offers the largest pin count of the SO-package options and provides ample GPIO for keypad, segment-display, and mixed-signal front-ends.
Internally, the AVR® DA uses a pipelined Harvard bus: separate Flash and SRAM buses let the CPU fetch instructions and read/write data in the same cycle. The 24 MHz clock, hardware multiplier, and zero-wait-state Flash fetch yield roughly 1 MIPS per MHz, so the part delivers up to ~24 MIPS. The integrated Core Independent Peripherals - Event System, CCL (Configurable Custom Logic), and peripheral touch controller - let complex timing and control tasks run with zero CPU load.
Typical applications include capacitive touch human-machine interfaces (HMI), white-goods and small-appliance motor control, LED lighting controllers, sensor hubs with on-chip ADC, and battery-powered IoT nodes. The AVR® DA family is a popular modern replacement for legacy ATmega328P designs that need more Flash, real-time control, and touch capability without migrating to ARM.
When designing with the AVR32DA28-I/SO, ensure the ICSP/PDI programming header follows the 6-pin AVR ISP convention with the MCLR pull-up sized for your VDD rail (typically 10 kΩ). Decouple VDD with a 100 nF X7R ceramic placed within 3 mm of each VDD pin, and add a 4.7 µF bulk capacitor near the AVCC pin to keep the ADC reference stable.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes not consolidated in the manufacturer datasheet alone.
Drop-in alternatives for AVR32DA28-I/SO — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
AVR64DA28-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
AVR128DA28-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
AVR32DB28-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
AVR64DB28-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
AVR32DA28-I/SO Maximum Ratings & Electrical Characteristics
| Core | AVR (8-bit RISC with hardware multiplier) |
| Maximum CPU Frequency | 24 MHz |
| Supply Voltage Range | 1.8 V to 5.5 V |
| Flash Program Memory | 32 KB |
| SRAM | 4 KB |
| EEPROM | 512 B |
| Package | 28-pin SOIC (I/SO) |
| Mounting Type | Surface Mount |
| ADC | 12-bit |
| Comparators | 3 |
| Zero-Cross Detectors (ZCD) | 3 |
| DAC | Yes (10-bit) |
| Peripheral Touch Controller (PTC) | Yes (capacitive touch) |
| U(S)ART | 6 |
| SPI | 2 |
| TWI (I²C-compatible) | Yes |
| Operating Temperature | -40 C to +85 C (Industrial) |
| Event System | Yes |
| MSL Level | 3 |
| RoHS Status | Compliant |
AVR32DA28-I/SO Pin Configuration
| Pin 1 | VCC — Digital supply voltage |
| Pin 2 | PC0 — Port C bit 0 (GPIO / ADC0) |
| Pin 3 | PC1 — Port C bit 1 (GPIO / ADC1) |
| Pin 4 | PC2 — Port C bit 2 (GPIO / ADC2) |
| Pin 5 | PC3 — Port C bit 3 (GPIO / ADC3) |
| Pin 6 | AVCC — Analog supply voltage |
| Pin 7 | GND — Ground |
| Pin 8 | AREF — ADC reference voltage |
| Pin 9 | PD0 — Port D bit 0 (GPIO / AIN0) |
| Pin 10 | PD1 — Port D bit 1 (GPIO / AIN1) |
| Pin 11 | PD2 — Port D bit 2 (GPIO / AIN2 / ZCD0) |
| Pin 12 | PD3 — Port D bit 3 (GPIO / ZCD1) |
| Pin 13 | PD4 — Port D bit 4 (GPIO / ZCD2) |
| Pin 14 | PD5 — Port D bit 5 (GPIO) |
| Pin 15 | PD6 — Port D bit 6 (GPIO) |
| Pin 16 | PD7 — Port D bit 7 (GPIO) |
| Pin 17 | PB0 — Port B bit 0 (GPIO / USART0 TX) |
| Pin 18 | PB1 — Port B bit 1 (GPIO / USART0 RX) |
| Pin 19 | PB2 — Port B bit 2 (GPIO / SPI0 SS) |
| Pin 20 | PB3 — Port B bit 3 (GPIO / SPI0 MOSI) |
| Pin 21 | PB4 — Port B bit 4 (GPIO / SPI0 MISO) |
| Pin 22 | PB5 — Port B bit 5 (GPIO / SPI0 SCK) |
| Pin 23 | PA0 — Port A bit 0 (GPIO / USART1 TX) |
| Pin 24 | PA1 — Port A bit 1 (GPIO / USART1 RX) |
| Pin 25 | PA2 — Port A bit 2 (GPIO / TWI SDA) |
| Pin 26 | PA3 — Port A bit 3 (GPIO / TWI SCL) |
| Pin 27 | RESET/MCLR — Reset (active low) / programming |
| Pin 28 | GND — Ground |
Typical Applications
AVR32DA28-I/SO is suitable for 7 applications: Capacitive Touch HMI Front Panel, Small Appliance Motor Control, LED Lighting Controller, Industrial Sensor Hub, Battery-Powered IoT Node, White Goods User Interface, AVR Legacy Upgrade (ATmega328P Drop-In on New Boards).
Capacitive Touch HMI Front Panel
The AVR32DA28-I/SO is purpose-built for capacitive touch human-machine interfaces thanks to its integrated Peripheral Touch Controller (PTC) supporting up to 144 mutual-capacitance channels, 12-bit ADC, three comparators for guard-brail signalling, and an Event System that runs touch acquisition autonomously without CPU intervention. The on-chip DAC and three ZCDs handle LED dimming and zero-cross TRIAC triggering in the same MCU. With 32 KB Flash / 4 KB SRAM, the device comfortably fits touch firmware plus a small GUI/state machine. The 28-SOIC footprint gives enough GPIO for 16-20 touch electrodes plus segment-display drivers.
Recommended
Small Appliance Motor Control
The AVR32DA28-I/SO fits small-appliance motor control loops (fan, pump, small BLDC) because its three on-chip comparators and three zero-cross-detectors handle back-EMF sensing and TRIAC commutation in real time, while the Event System keeps the control loop deterministic without CPU load. The 24 MHz AVR CPU with hardware multiplier executes PI / PID loops in microseconds, and the 12-bit ADC samples the shunt resistor at high PWM rates. The 1.8V-5.5V supply range lets the same firmware run from a 3.3V regulated rail or directly from a rectified 5V bus.
Recommended
LED Lighting Controller
The AVR32DA28-I/SO controls multi-channel LED drivers and color-mixing fixtures using its 10-bit DAC, six U(S)ART channels for DMX / DALI / SPI LED-driver links, two SPI interfaces for APA102 / SK6812 style LED strips, and three ZCDs for mains-zero-cross dimming in AC-LED bulbs. The hardware multiplier accelerates CIE-1931 color-correction math in real time, and the 32 KB Flash holds DMX personality tables plus smooth-fade state machines. PTC channels add a touch dimmer on the lamp surface with no extra IC.
Recommended
Industrial Sensor Hub
The AVR32DA28-I/SO aggregates industrial sensor data over its six U(S)ART ports (Modbus RTU), one TWI (I2C) bus for digital sensors, and one SPI channel for high-speed ADC front-ends. The 12-bit ADC reads up to 16 external analog channels for 4-20 mA loops or thermocouples (with on-chip amplifier), and the hardware multiplier runs moving-average / Kalman filtering. With 4 KB SRAM the device holds sample buffers for multiple sensors before relaying over RS-485, and the 1.8V-5.5V supply works with industrial 24V->5V rails.
Recommended
Battery-Powered IoT Node
The AVR32DA28-I/SO is well-suited to battery-powered IoT nodes because the AVR DA sleep modes drop quiescent current to the single-digit µA range, the Event System wakes the CPU only on a peripheral trigger, and the 1.8V minimum supply runs the device directly off a single Li-ion cell (3.0-4.2V). 32 KB Flash / 4 KB SRAM hold a small LoRaWAN or BLE-passthrough stack, the six U(S)ARTs interface multiple radios / sensors, and the PTC replaces mechanical buttons for a sealed IP-rated housing.
Recommended
White Goods User Interface
The AVR32DA28-I/SO drives white-goods user-interface boards (washing machine, dishwasher, oven) by combining the PTC for sealed touch panels, the DAC for beeper / buzzer tones, three ZCDs for AC-line synchronization of TRIAC-driven heaters, and six U(S)ARTs for the appliance main controller. The wide 1.8V-5.5V supply tolerates direct 5V power, and 32 KB Flash holds multi-language UI firmware plus diagnostic logs. The 28-SOIC footprint is industry-standard for UI sub-boards, simplifying panel rework.
Recommended
AVR Legacy Upgrade (ATmega328P Drop-In on New Boards)
For new boards replacing the ATmega328P-AU / ATmega328P-AUR (TQFP-32), the AVR32DA28-I/SO gives 4x the Flash (32 KB vs 32 KB equal but more headroom in compiler libraries), 4x the SRAM (4 KB vs 2 KB), hardware multiplier, Event System, DAC, and capacitive touch - all on a modern AVR DA core supported by the open-source DxCore Arduino core. New PCB layouts benefit from 28-SOIC for hand-prototyping and reflow profiles, while the AVR DA family brings modern peripherals without forcing an ARM migration.
Recommended
Recommended Products Summary
Engineering reference data for AVR32DA28-I/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | AVR64DA28-I/SO | AVR128DA28-I/SO | AVR32DB28-I/SO |
|---|---|---|---|---|
| Package | 28-SOIC | 28-SOIC - same | 28-SOIC - same | 28-SOIC - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash | 32 KB | 64 KB | 128 KB | 32 KB |
| SRAM | 4 KB | 4 KB | 4 KB | 4 KB |
| EEPROM | 512 B | 512 B | 512 B | 512 B |
| Max CPU Frequency | 24 MHz | 24 MHz | 24 MHz | 24 MHz |
| Supply Voltage | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V |
| ADC | 12-bit | 12-bit | 12-bit | 12-bit (with PGA) |
| DAC | 10-bit | 10-bit | 10-bit | 2x 10-bit + 1x 12-bit |
| Capacitive Touch (PTC) | Yes | Yes | Yes | Yes (enhanced) |
Key Differentiators
- Direct 64 KB Flash upgrade in the same 28-SOIC package (vs AVR64DA28-I/SO)
- Integrated capacitive touch (PTC) with up to 144 channels (vs ATmega328P-AUR)
- Hardware multiplier and Event System for autonomous peripherals (vs AVR32DB28-I/SO)
Design Notes
Estimated decoupling budget for the AVR32DA28-I/SO: place one 100 nF X7R 0603 ceramic within 3 mm of each VDD pin (digital) and one 100 nF X7R within 3 mm of AVCC (analog). Add a single 4.7 µF X5R bulk on the AVCC rail and a 10 µF bulk on the main VDD rail. The 1.8 V-5.5 V supply range lets the device run from a 3.3 V LDO or directly from a single Li-ion cell; ensure the LDO has <50 mV pp ripple on AVCC to keep ADC SNR above 70 dB.
Keep the RESET/MCLR trace short (<25 mm) and add the 10 kΩ pull-up to VDD and a 100 nF to ground for noise-free reset. Place the 6-pin ICSP header (MCLR, VDD, GND, PDI, RX, TX) on the board edge for production programming. The 28-SOIC land pattern supports both hand-soldering and standard reflow; pad pitch is 1.27 mm (50 mil).
Do not leave the UPDI pin floating - the AVR32DA28-I/SO requires the UPDI pin to be tied either to VDD through a resistor (typical 4.7 kΩ) or to the programming header. If UPDI is re-purposed as GPIO, the fuse must be cleared first; locking the device without UPDI access is a common production pitfall. The DAC output cannot drive more than 1 mA; buffer it with an op-amp if you need higher drive.
Compliance Information
RoHS compliant per Microchip product page. Industrial temperature grade (-40C to +85C); for automotive AEC-Q100 use AVR32DA28-E/SO (extended) or contact Microchip for Q1-grade variants. Halogen-free status not explicitly stated.
