ATMEGA324A-AU - AVR MCU 32KB Flash 20MHz TQFP-44 | Microchip
MPN: ATMEGA324A-AU β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.42 | $3.42 |
| 10 | $3.05 | $30.50 |
| 100 | $2.71 | $271.00 |
| 500 | $2.38 | $1,190.00 |
| 1,000 | $2.09 | $2,090.00 |
ATMEGA324A-AU Overview
An 8-bit microcontroller is a self-contained computing IC that integrates a processor core, program memory, data memory, and peripherals such as timers, serial interfaces, and ADCs on a single die. Within the power-management hierarchy of embedded systems, it sits above discrete logic and below application processors, and is typically paired with a voltage regulator, clock source, and reset supervisor to form a complete control node.
Key features include the AVR Advanced RISC architecture with 131 powerful instructions, most executing in a single clock cycle, plus 32 general-purpose working registers directly connected to the ALU. The device provides a real time counter, three flexible timers/counters with compare modes and PWM, and serial peripherals including USART, SPI (Serial Peripheral Interface), and 2-Wire interface (I2C/TWI), enabling rich connectivity in a compact footprint.
Technical depth: Flash memory carries read-while-write capability, allowing firmware self-programming for bootloaders and field upgrades via In-System Programming (ISP). The enhanced core sustains close to 1 MIPS per MHz throughput, so a 16 MHz crystal delivers roughly 16 MIPS while remaining within the 4.5V to 5.5V supply band for full-speed industrial operation. Multiple power-saving sleep modes and the PicoPower-derived power-management heritage allow microamp-level standby currents in battery-aware designs.
Typical applications include industrial automation and control panels, home appliances and HVAC controllers, sensor and data-logging nodes, and motor control sub-systems where the 32 I/O lines and PWM timers are fully utilized.
Design consideration: use 0.1uF decoupling capacitors on both VCC/AVCC pairs and route the analog ground reference carefully to preserve ADC accuracy; verify that the supply voltage supports your chosen clock frequency per the Microchip speed-grade curve.
This page synthesizes distributor pricing, drop-in same-family alternatives, pinout data, and practical design notes not found on a single manufacturer page.
Drop-in alternatives for ATMEGA324A-AU β 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 ATMEGA324A-AU (same form factor and footprint) β differing in Package, Serial Interfaces, RoHS Status, Core Architecture, EEPROM.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA324PA-AU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA324PB-ANR
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA164A-AU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA644A-AU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA16A-AU
β Drop-Inβ In Stock
$2.05 / Unit
View Datasheet βATMEGA32-16AUR
β Drop-Inβ In Stock
$3.41 / Unit
View Datasheet βATMEGA324A-AU Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Flash Memory | 32 KB (ISP, read-while-write) |
| EEPROM | 1 KB |
| SRAM | 2 KB |
| Maximum CPU Frequency | 20 MHz |
| Supply Voltage Range | 1.8 V to 5.5 V (speed-grade dependent) |
| General Purpose I/O | 32 lines |
| General Purpose Working Registers | 32 |
| Instructions | 131 (most single-cycle) |
| Timers/Counters | 3 |
| Real Time Counter | Yes |
| Serial Interfaces | USART, SPI, 2-Wire (I2C/TWI) |
| In-System Programming | Yes (ISP) |
| Package Type | TQFP-44, 10 x 10 mm, 1 mm height, 0.8 mm pitch |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C (Industrial) |
| Life Cycle Stage | Active |
| RoHS Status | Compliant |
ATMEGA324A-AU Pin Configuration
| Pin 1 | PA7 (ADC7/D7) β Port A bit 7 / ADC channel 7 |
| Pin 2 | PA6 (ADC6/D6) β Port A bit 6 / ADC channel 6 |
| Pin 3 | PA5 (ADC5/D5) β Port A bit 5 / ADC channel 5 |
| Pin 4 | PA4 (ADC4/D4) β Port A bit 4 / ADC channel 4 |
| Pin 5 | PA3 (ADC3/D3) β Port A bit 3 / ADC channel 3 |
| Pin 6 | PA2 (ADC2/D2) β Port A bit 2 / ADC channel 2 |
| Pin 7 | PA1 (ADC1/D1) β Port A bit 1 / ADC channel 1 |
| Pin 8 | PA0 (ADC0/D0) β Port A bit 0 / ADC channel 0 |
| Pin 9 | PB0 (SS) β Port B bit 0 / SPI Slave Select |
| Pin 10 | PB1 (SCK) β Port B bit 1 / SPI Clock |
| Pin 11 | PB2 (MOSI) β Port B bit 2 / SPI Master Out Slave In |
| Pin 12 | PB3 (MISO) β Port B bit 3 / SPI Master In Slave Out |
| Pin 13 | PB4 (OC2A) β Port B bit 4 / Timer2 compare output A / alternate SS |
| Pin 14 | PB5 (OC1A) β Port B bit 5 / Timer1 compare output A |
| Pin 15 | PB6 (OC1B) β Port B bit 6 / Timer1 compare output B |
| Pin 16 | PB7 (OC0A/OC1C) β Port B bit 7 / Timer0 or Timer1 compare output |
| Pin 17 | RESET β Active-low reset input |
| Pin 18 | VCC β Digital supply voltage |
| Pin 19 | GND β Digital ground |
| Pin 20 | XTAL2 β Crystal oscillator output / external clock output |
| Pin 21 | XTAL1 β Crystal oscillator input / external clock input |
| Pin 22 | PC0 (SCL) β Port C bit 0 / 2-Wire clock |
| Pin 23 | PC1 (SDA) β Port C bit 1 / 2-Wire data |
| Pin 24 | PC2 (TCK) β Port C bit 2 / JTAG test clock |
| Pin 25 | PC3 (TMS) β Port C bit 3 / JTAG test mode select |
| Pin 26 | PC4 (TDO) β Port C bit 4 / JTAG test data out |
| Pin 27 | PC5 (TDI) β Port C bit 5 / JTAG test data in |
| Pin 28 | PC6 (TOSC1) β Port C bit 6 / RTC crystal input |
| Pin 29 | PC7 (TOSC2) β Port C bit 7 / RTC crystal output |
| Pin 30 | PD0 (RXD0) β Port D bit 0 / USART0 receive |
| Pin 31 | PD1 (TXD0) β Port D bit 1 / USART0 transmit |
| Pin 32 | PD2 (RXD1/INT0) β Port D bit 2 / USART1 receive / external interrupt 0 |
| Pin 33 | PD3 (TXD1/INT1) β Port D bit 3 / USART1 transmit / external interrupt 1 |
| Pin 34 | PD4 (ICP1) β Port D bit 4 / Timer1 input capture |
| Pin 35 | PD5 (XCK1) β Port D bit 5 / USART1 external clock |
| Pin 36 | PD6 (XCK0/TOSC2) β Port D bit 6 / USART0 external clock |
| Pin 37 | PD7 (OC2A/ICP) β Port D bit 7 / Timer2 compare or input capture |
| Pin 38 | AREF β ADC analog reference input |
| Pin 39 | AGND β Analog ground |
| Pin 40 | AVCC β ADC supply voltage |
| Pin 41 | PB5 (SCK, alt) β Port B bit 5 alternate location / SPI clock |
| Pin 42 | PB6 (MOSI, alt) β Port B bit 6 alternate location / SPI MOSI |
| Pin 43 | PB7 (MISO, alt) β Port B bit 7 alternate location / SPI MISO |
| Pin 44 | PB4 (SS, alt) β Port B bit 4 alternate location / SPI Slave Select |
Typical Applications
ATMEGA324A-AU is suitable for 6 applications: Industrial Automation and Control Panels, Home Appliances and HVAC Controllers, Sensor Nodes and Data Logging, Motor Control Sub-Systems, Security and Access Control Panels, Consumer Electronics and LED Lighting Control.
Industrial Automation and Control Panels
The ATMEGA324A-AU fits industrial control panels because its 32 GPIO lines eliminate the need for external port expanders in relay-heavy panel designs, and its three timers provide hardware PWM for actuator positioning. Running from a 5V industrial rail within the 4.5V to 5.5V full-speed band, the AVR core sustains roughly 1 MIPS per MHz, giving adequate headroom for Modbus-over-USART polling loops at 16 to 20 MHz. The SPI and 2-Wire interfaces connect ADC front ends and EEPROM configuration stores, while the industrial temperature grade down to -40C matches cabinet environments. Field firmware updates via read-while-write ISP Flash allow maintenance crews to reflash deployed panels over a serial link without desoldering the MCU, reducing downtime and service cost.
Recommended
Home Appliances and HVAC Controllers
Appliance and HVAC control boards benefit from the ATMEGA324A-AU's combination of 32KB ISP Flash, 1KB EEPROM for storing user settings and error logs, and 2KB SRAM for state machines. The real time counter and asynchronous timer support time-of-day and scheduling functions from a 32.768 kHz crystal on the TOSC pins, while hardware PWM timers drive triac-trigger, fan-speed, and damper-motor control outputs directly from the 32 I/O lines. Supply operation from 1.8V to 5.5V accommodates designs migrating to 3.3V logic, and the device's sleep modes cut standby current for always-plugged appliances. Field firmware upgrades through the read-while-write bootloader let manufacturers deliver feature updates without a service call, which is increasingly required for connected appliance platforms.
Recommended
Sensor Nodes and Data Logging
The ATMEGA324A-AU is a strong fit for multi-sensor data loggers because its 2KB SRAM buffers sampled data, the 1KB EEPROM retains calibration constants across power cycles, and the dual USART design allows one port for sensor modules and a second for telemetry. The SPI bus streams data from high-resolution ADCs, while the 2-Wire interface manages RTC chips and environmental sensors. With a 10-bit ADC and internal 2.56V or VCC reference options on the AREF/AVCC pins, moderate-precision analog capture is handled on-chip. Operating down to 1.8V lets the MCU run directly from two alkaline cells or a single Li-SOCl2 cell through a regulator, and sleep modes extend battery life in periodic-wake logging applications typical of cold-chain and environmental monitoring.
Recommended
Motor Control Sub-Systems
For DC and stepper motor control, the ATMEGA324A-AU provides three flexible timers with compare channels and PWM generation, sufficient to drive two to three motors with hardware-timed waveforms rather than bit-banged software loops. The external interrupt inputs on port D capture encoder and Hall-sensor feedback, and the input-capture function timestamps speed measurements with timer resolution for closed-loop control. The 32 I/O lines leave ample pins for limit switches, H-bridge direction logic, and fault feedback. Executing most of its 131 instructions in a single cycle at up to 20 MHz, the core closes current-loop updates in the tens-of-kilohertz range. Designers should route motor power grounds away from the AVCC analog domain to preserve ADC feedback accuracy.
Recommended
Security and Access Control Panels
Access control and alarm panels use the ATMEGA324A-AU's 32 I/O lines to poll keypads, door sensors, and relays across multiple zones, while the 2-Wire interface reads Real Time Clock modules for time-stamped event logs stored in the 1KB EEPROM. The dual USART capability separates a local service port from an RS-485 network port, enabling daisy-chained panel topologies. JTAG on port C supports boundary-scan manufacturing test and on-chip debugging during development, which shortens certification cycles for security products. Read-while-write Flash supports cryptographic key updates in the field through an authenticated bootloader, and the industrial temperature rating maintains operation in unconditioned outdoor cabinets from -40C upward.
Recommended
Consumer Electronics and LED Lighting Control
In consumer products and LED lighting fixtures, the ATMEGA324A-AU drives multi-channel PWM dimming from its three timers while its 32 I/O lines handle touch-key scanning, indicator LEDs, and IR remote receivers across port pins. The device's 1.8V to 5.5V supply range matches rechargeable-battery and USB-powered products, and sleep modes meet standby power targets for energy-label compliance. The USART supports Bluetooth and sub-GHz radio modules for smart-lighting links, and the 32KB Flash leaves room for over-the-air-style update bootloaders relayed through the radio. Its wide availability across 11 distributors, confirmed by Octopart as of 2026-09-17, reduces line-down risk for high-volume consumer production schedules.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA324A-AU β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA324PA-AU | ATMEGA324PB-ANR | ATMEGA164A-AU | ATMEGA644A-AU | ATMEGA32-16AUR |
|---|---|---|---|---|---|---|
| Package | TQFP-44 (10 x 10 mm, 0.8 mm pitch) | TQFP-44 - same | TQFP-44 - same | TQFP-44 - same | TQFP-44 - same | TQFP-44 - same |
| Brand | Microchip Technology (Atmel) | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 32 KB | 32 KB | 32 KB | 16 KB | 64 KB | 32 KB |
| SRAM | 2 KB | 2 KB | 2 KB | 1 KB | 4 KB | 2 KB |
| EEPROM | 1 KB | 1 KB | 1 KB | 512 B | 2 KB | 1 KB |
| Max Clock Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 16 MHz |
| Minimum Supply Voltage | 1.8 V | 1.8 V | 1.8 V | 1.8 V | 1.8 V | 2.7 V (16A grade) |
| GPIO Lines | 32 | 32 | 34 | 32 | 32 | 32 |
| Special Features | RWW Flash, JTAG, RTC, 2x USART | RWW Flash, JTAG, RTC, 2x USART, lower power | Core Independent Peripherals, PicoPower | RWW Flash, JTAG, RTC, 2x USART | RWW Flash, JTAG, RTC, 2x USART, larger memory | Legacy core, JTAG, no RWW Flash |
Key Differentiators
- Read-while-write ISP Flash enables field bootloaders (vs ATMEGA32-16AUR)
- 1.8V minimum supply for 3.3V and battery designs (vs ATMEGA324P-20AU)
- Dual USART on the standard ATmega324 footprint (vs ATMEGA164A-AU)
- Trade-off: fewer peripherals than the PB variant (vs ATMEGA324PB-ANR)
Design Notes
Decouple both VCC (pin 18) and AVCC (pin 40) with 0.1uF ceramic capacitors placed within 5 mm of each pin, plus a 10uF bulk capacitor near the supply entry. Tie AVCC to VCC through a small LC filter (10uH + 0.1uF) when ADC accuracy matters. Connect AGND (pin 39) to a quiet analog ground island joined to digital ground at a single star point. The 0.8 mm pitch TQFP-44 fanout is straightforward on a two-layer board, but keep the crystal traces on XTAL1/XTAL2 short and guarded by ground.
Verify the supply voltage against your clock frequency using the Microchip speed-grade curves: full 20 MHz operation requires the higher end of the 1.8V to 5.5V range (5V typical). Do not enable JTAG on port C unintentionally in production fuses - the default fuse state may free port C pins, but an incorrectly set JTAGEN fuse steals PC2-PC5 from your application. When migrating from ATMEGA32 to ATMEGA324A, register maps and fuse names differ; recompile rather than relinking old hex files.
Estimated: ATmega324A active current is roughly 1-2 mA per MHz on the AVR core (approximately 16-40 mA at 16-20 MHz from a 5V rail), so plan the 5V regulator with at least 50 mA headroom plus I/O sink/source loads (20 mA absolute max per pin). In sleep/idle modes current drops orders of magnitude; design the sleep-wake budget with the datasheet power consumption tables rather than estimates for battery products. Brown-out detection should be enabled via fuse for 5V industrial environments to prevent EEPROM corruption during power sag.
For SPI bus integrity at 20 MHz (SCK up to fosc/2 in master mode), keep SCK and MOSI traces under 10 cm on two-layer boards and add 22-33 ohm series resistors on lines driving long cables to damp ringing. For the 2-Wire interface, always use external 4.7k pull-ups on SCL/SDA (pins 22-23) sized to bus capacitance per the I2C specification - the internal pull-ups are too weak for fast-mode operation. Route the second USART (PD2/PD3) away from the crystal section when using RS-485 transceivers.
Compliance Information
Life cycle stage ACTIVE per digchip datasheet summary. Industrial grade (-40C to +85C) per Mouser listing. REACH/halogen-free declarations should be confirmed via official Microchip material declaration documents.
