ATMEGA809-AFR - 8-Bit AVR MCU 20MHz 8KB Flash 48-TQFP | Microchip
MPN: ATMEGA809-AFR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.24 | $2.24 |
| 10 | $2.08 | $20.80 |
| 100 | $1.89 | $189.00 |
| 500 | $1.71 | $855.00 |
| 1,000 | $1.55 | $1,550.00 |
ATMEGA809-AFR Overview
An 8-bit microcontroller (MCU) integrates a processor core, memory, and peripherals on a single chip, sitting at the lowest level of the embedded-systems hierarchy: MCU -> embedded processor -> system-on-chip. The megaAVR 0-series is Microchip's modernized AVR family, and the ATmega809 is its entry-density 48-pin member.
Key features include the AVR RISC core with a single-cycle hardware multiplier executing most instructions in one clock cycle, Core Independent Peripherals (CIPs) that operate without CPU intervention, and a configurable Event System that routes peripheral signals internally. Peripherals include a 10-bit ADC, analog comparators, multiple 16-bit timers, USARTs, SPI, and TWI (I2C). Functional Safety (FuSa) support positions it for safety-relevant designs.
Architecturally, the device uses a modified Harvard architecture with separate program and data buses, single-level instruction pipelining, and low-power sleep modes down to sub-microamp levels. Memory is organized as 8K x 8 Flash with in-system self-programming, plus 256 bytes of nonvolatile EEPROM for calibration data.
Typical applications include industrial automation nodes, home appliances, IoT sensor endpoints, motor control auxiliaries, and consumer electronics where the 48-pin count supports multiple communication ports.
Design consideration: keep the AVDD/decoupling layout per the datasheet, and note the PA0/UPDI multiplexing when planning debug access.
This page adds value beyond the datasheet with tiered distributor pricing (as of 2026-09-18), drop-in family alternatives, pinout data, and application guidance for the megaAVR 0-series.
Drop-in alternatives for ATMEGA809-AFR — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with ATMEGA809-AFR (same form factor and footprint) — differing in Core Processor, Peripherals, Series, Package, Connectivity.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA4809-AU
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
ATMEGA3209-AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.06 / Unit
View Datasheet →ATMEGA1609-AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.15 / Unit
View Datasheet →ATMEGA4808-MUR
✅ Drop-In✓ In Stock
$1.22 / Unit
View Datasheet →ATMEGA809-AFR Maximum Ratings & Electrical Characteristics
| Core Processor | AVR |
| Core Size | 8-Bit |
| Maximum Clock Frequency | 20 MHz |
| Flash Memory | 8 KB (8K x 8) |
| SRAM | 1 KB |
| EEPROM | 256 bytes |
| Supply Voltage Range | 1.8 V to 5.5 V |
| Series | megaAVR 0-series |
| Peripherals | Brown-out Detect/Reset, POR, WDT |
| Hardware Multiplier | Yes |
| Number of I/O | 41 |
| Package | 48-TQFP (7x7 mm) |
| Mounting Type | Surface Mount |
| Special Features | Functional Safety (FuSa), Event System, Core Independent Peripherals |
| Programming Interface | UPDI |
ATMEGA809-AFR Pin Configuration
| Pin 1 | VDD — Power supply |
| Pin 2 | GND — Ground |
| Pin 3 | PA0/UPDI — Port A bit 0 / UPDI programming interface |
| Pin 4 | PA1 — Port A bit 1 |
| Pin 5 | PA2 — Port A bit 2 |
| Pin 6 | PA3 — Port A bit 3 |
| Pin 7 | PA4 — Port A bit 4 |
| Pin 8 | PA5 — Port A bit 5 |
| Pin 9 | PA6 — Port A bit 6 |
| Pin 10 | PA7 — Port A bit 7 |
| Pin 11 | VDDIO2 — Port A supply domain |
| Pin 12 | GND — Ground |
| Pin 13 | PB0 — Port B bit 0 |
| Pin 14 | PB1 — Port B bit 1 |
| Pin 15 | PB2 — Port B bit 2 |
| Pin 16 | PB3 — Port B bit 3 |
| Pin 17 | PB4 — Port B bit 4 |
| Pin 18 | PB5 — Port B bit 5 |
| Pin 19 | GND — Ground |
| Pin 20 | VDD — Power supply |
| Pin 21 | PC0 — Port C bit 0 |
| Pin 22 | PC1 — Port C bit 1 |
| Pin 23 | PC2 — Port C bit 2 |
| Pin 24 | PC3 — Port C bit 3 |
| Pin 25 | PC4 — Port C bit 4 |
| Pin 26 | PC5 — Port C bit 5 |
| Pin 27 | PC6 — Port C bit 6 |
| Pin 28 | PC7 — Port C bit 7 |
| Pin 29 | PD0 — Port D bit 0 |
| Pin 30 | PD1 — Port D bit 1 |
| Pin 31 | PD2 — Port D bit 2 |
| Pin 32 | PD3 — Port D bit 3 |
| Pin 33 | PD4 — Port D bit 4 |
| Pin 34 | PD5 — Port D bit 5 |
| Pin 35 | PD6 — Port D bit 6 |
| Pin 36 | PD7 — Port D bit 7 |
| Pin 37 | GND — Ground |
| Pin 38 | VDD — Power supply |
| Pin 39 | PE0 — Port E bit 0 |
| Pin 40 | PE1 — Port E bit 1 |
| Pin 41 | PE2 — Port E bit 2 |
| Pin 42 | PE3 — Port E bit 3 |
| Pin 43 | PF0 — Port F bit 0 / TOSC1 |
| Pin 44 | PF1 — Port F bit 1 / TOSC2 |
| Pin 45 | PF2 — Port F bit 2 |
| Pin 46 | PF3 — Port F bit 3 |
| Pin 47 | PF4 — Port F bit 4 |
| Pin 48 | PF5 — Port F bit 5 |
Typical Applications
ATMEGA809-AFR is suitable for 6 applications: Industrial Automation Nodes, Home Appliances, IoT Sensor Endpoints, Motor Control Auxiliary Logic, Consumer Electronics Control, Building Automation and Lighting Control.
Industrial Automation Nodes
The ATMEGA809-AFR fits industrial sensor and actuator nodes because its 1.8V-5.5V supply tolerates noisy 5V industrial rails, while Core Independent Peripherals (CIPs) handle timer, PWM, and communication tasks without CPU intervention, improving real-time determinism. In a typical node, USART1 links to an RS-485 transceiver for Modbus RTU, two 16-bit timers generate PWM for actuators, and the 10-bit ADC samples up to 12 analog channels. The Event System routes comparator or ADC events directly to timer capture, enabling sub-microsecond responses independent of firmware latency. Brown-out reset and a windowed watchdog maintain safe states through power dips. Its Functional Safety support further suits machine-control subfunctions where documented failure modes are required.
Recommended
Home Appliances
Home appliance control boards - washing machines, dishwashers, coffee makers - benefit from the ATmega809's 41 I/O lines, multiple 16-bit PWM channels, and low-cost profile in the 48-pin TQFP. The device drives triac or relay outputs, reads tactile switches and encoder inputs via pin-change interrupts, and sequences motors using hardware timers that keep running even during interrupt-heavy loops thanks to CIP architecture. The 256-byte EEPROM stores cycle counters and calibration constants through power cycles without external NVM. Operating from an unregulated 5V derived from the appliance supply, the wide 1.8-5.5V input range absorbs rail sag during motor start. The 20 MHz core with hardware multiplier handles simple FOC or commutation assist routines.
Recommended
IoT Sensor Endpoints
For battery-powered IoT sensor endpoints, the ATmega809 offers multiple sleep modes with low standby current, and peripherals such as the ADC and analog comparator can be operated in low-power modes to wake the core on threshold events via the Event System. A typical endpoint samples a sensor over TWI (I2C) every few seconds, packs readings into 1 KB SRAM, and transmits via a USART-connected radio module, then sleeps for minutes. The hardware multiplier accelerates averaging and CRC calculations in the 8 KB Flash firmware. Because the part runs down to 1.8V, a single Li-SOCl2 cell can power it directly without a boost converter, reducing quiescent losses and board area in sealed sensor housings.
Recommended
Motor Control Auxiliary Logic
In motor-driven products, the ATmega809 serves as auxiliary logic supervising a dedicated motor driver: generating PWM reference signals from its 16-bit timers with 20 MHz resolution, monitoring current via the 10-bit ADC and internal analog comparator for overcurrent trip, and communicating status to the main controller over SPI or USART. The Core Independent Peripherals allow a comparator event to gate timer output in hardware, providing a fast protection path without firmware jitter. The Event System ties tachometer input capture directly to a timer for closed-loop speed measurement. With 1.8-5.5V operation it interfaces cleanly with both 3.3V gate drivers and 5V legacy boards. FuSa support adds documentation value for safety-relevant stop functions.
Recommended
Consumer Electronics Control
Consumer products such as remote controls, small displays, and charging accessories use the ATmega809's balanced feature set: 41 GPIOs drive segment LCD drivers, keypads, and LEDs; hardware SPI runs fast display updates at up to 20 MHz; and the hardware multiplier supports color math or battery fuel-gauge algorithms. The device's 5V tolerance across its full range simplifies interfaces with USB-derived supplies, while the 3.3V compatibility suits coin-cell or Li-ion designs. Low-cost 48-TQFP packaging keeps BOM spend minimal in high-volume consumer builds. The 8 KB Flash typically holds HID-style firmware, button debouncing, and charge-state state machines with room to spare, and the 256-byte EEPROM stores user settings persistently across battery swaps.
Recommended
Building Automation and Lighting Control
Building automation panels and DALI-style lighting controllers exploit the ATmega809's multiple USARTs (one for DALI, one for RS-485 backhaul), TWI for sensor expansion, and precise 16-bit PWM for dimming outputs. Core Independent Peripherals keep PWM channels running glitch-free while the CPU manages network protocol parsing, and the Event System links zero-crossing detection comparators directly to PWM synchronization for flicker-free phase control. The 1.8-5.5V supply range allows powering directly from mains-derived auxiliary rails. Brown-out detection and watchdog timer guarantee recovery from grid disturbances common in large buildings. Functional Safety documentation support aids occupancy-safety functions such as emergency lighting verification routines required in commercial installations.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA809-AFR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA4809-AU | ATMEGA3209-AU | ATMEGA1609-AU | ATMEGA4808-MUR |
|---|---|---|---|---|---|
| Package | 48-TQFP (7x7 mm) | 48-TQFP (7x7 mm) - same | 48-TQFP (7x7 mm) - same | 48-TQFP (7x7 mm) - same | 48-TQFP (7x7 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 8 KB | 48 KB | 32 KB | 16 KB | 8 KB |
| SRAM | 1 KB | 6 KB | 2 KB | 2 KB | 1 KB |
| EEPROM | 256 bytes | 256 bytes | 256 bytes | 256 bytes | 256 bytes |
| Max Clock Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 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 | 1.8 V to 5.5 V |
Key Differentiators
- Lowest cost in the 48-pin megaAVR 0-series family (vs ATMEGA4809-AU)
- Functional Safety (FuSa) support in the family (vs ATMEGA1609-AU)
- Trade-off: limited Flash headroom (vs ATMEGA4809-AU)
Design Notes
Decouple every VDD and VDDIO2 pin with 100 nF ceramic capacitors placed within 2 mm of the pin, plus one bulk 4.7-10 uF capacitor near the package. The 48-TQFP (7x7 mm) exposes VDD on pins 1, 20, 38 and VDDIO2 on pin 11; a shared decoupling network across multiple VDD pins degrades high-frequency noise rejection and can cause ADC inaccuracies. Use a solid ground plane on layer 2 and connect all GND pins (2, 12, 19, 37) directly to it with thermal-relief-free vias for lowest ground impedance.
UPDI is multiplexed with PA0 on pin 3. If PA0 is wired to an external driver that can source current into the pin, the UPDI programmer may fail to enter programming mode after the board is assembled - a common rework-driver. Route PA0 to a programming header (or provide a series resistor plus isolation jumper) even in production boards. Also verify the fuse configuration for BOD and WDT early: once the watchdog is fuse-locked it cannot be disabled in software, complicating low-power firmware testing.
The 1.8V-5.5V supply range permits direct battery operation, but maximum safe clock frequency scales with VDD in AVR devices; validate the frequency-voltage curve in the family datasheet before running 20 MHz below the datasheet's stated minimum VDD for that frequency. Estimated: at 5V with 20 mA average I/O and core current, dissipation is about 100 mW, trivial for the 48-TQFP, so no thermal design is required at room ambient; low-power sleep mode selection matters far more than thermal management in battery designs.
Compliance Information
Compliance status not stated in the provided verified web data. Microchip standard catalog parts are typically RoHS compliant; confirm on the official Microchip product page before export-controlled orders.
