ATMEGA325A-AN - 8-bit AVR MCU 32KB 20MHz | Microchip
MPN: ATMEGA325A-AN ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.95 | $3.95 |
| 10 | $3.56 | $35.60 |
| 100 | $3.08 | $308.00 |
| 500 | $2.76 | $1,380.00 |
| 1,000 | $2.42 | $2,420.00 |
ATMEGA325A-AN Overview
A microcontroller (MCU) is a complete computing system integrated onto a single chip, combining a processor core, program memory, data memory, and peripherals. The ATmega family sits within Microchip's broader AVR product line, which in turn belongs to the 8-bit microcontroller class within the semiconductor device hierarchy. MCUs like the ATmega325A execute embedded control code directly and are the workhorses of industrial automation, instrumentation, and consumer appliance design.
Key features include the advanced AVR RISC architecture executing 130 powerful instructions, most in a single clock cycle, plus 32 general-purpose 8-bit working registers that keep the datapath efficient. The 32 KB self-programmable Flash supports In-System Programming (ISP) with read-while-write capability, enabling field firmware updates without removing the device from the board. Peripheral richness - including USART serial ports, SPI, an 8-channel 10-bit ADC, timers with PWM outputs, and analog comparators - allows a single ATMEGA325A-AN to replace several discrete logic and analog ICs in a design.
The A-suffix silicon revision represents Microchip's ongoing ATmega core lineage with mature, well-characterized electrical performance. The internal oscillator option eliminates the need for an external crystal in cost-sensitive or timing-tolerant applications, while an external crystal interface supports precise 20 MHz operation for timing-critical designs. The 64-TQFP (14x14 mm) package provides 54 general-purpose I/O lines, giving enough pin count for parallel displays, keypads, and multi-peripheral buses.
Typical applications include industrial control panels, motor and appliance control, sensor acquisition systems, metering products, and hobby or educational embedded platforms. The generous Flash density accommodates C-based applications with communication stacks, while the 10-bit ADC serves analog sensor front ends directly.
Design consideration: the 2 KB SRAM is the main capacity constraint - engineers planning heavy buffering or RTOS-based designs should budget stack and heap usage carefully, or evaluate the pin-compatible ATmega3250 siblings for complementary options.
This page synthesizes distributor pricing, verified drop-in alternatives within the same 64-TQFP footprint, and practical design notes not found in a single manufacturer datasheet, giving engineers a one-stop selection resource.
Drop-in alternatives for ATMEGA325A-AN — 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 ATMEGA325A-AN (same form factor and footprint) — differing in RoHS Status, Package, Supply Voltage Range, Core Architecture, Number of I/O.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA325A-AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$3.12 / Unit
View Datasheet →ATMEGA325PA-AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$4.95 / Unit
View Datasheet →ATMEGA325-16AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.4 / Unit
View Datasheet →ATMEGA3250A-AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.5 / Unit
View Datasheet →ATMEGA3250P-20AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.8 / Unit
View Datasheet →ATMEGA3250PA-AUR
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.98 / Unit
View Datasheet →ATMEGA325A-AN Maximum Ratings & Electrical Characteristics
| Core Architecture | AVR 8-bit RISC |
| Program Memory Size | 32 KB (16K x 16) Flash |
| Program Memory Type | ISP FLASH with read-while-write |
| SRAM Size | 2 KB (2K x 8) |
| EEPROM Size | 1 KB |
| Maximum Clock Frequency | 20 MHz |
| Supply Voltage | 5 V |
| Number of I/O | 54 |
| General Purpose Working Registers | 32 x 8-bit |
| Instruction Set | 130 instructions, mostly single-cycle |
| Oscillator Type | Internal |
| Package / Case | 64-TQFP (14x14 mm) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +105C |
| Packaging | Tube |
| RoHS Status | Compliant |
| Lead Free | Yes |
ATMEGA325A-AN 64-tqfp (14x14 mm) Pin Configuration Guide
Pin configuration for ATMEGA325A-AN (64-tqfp (14x14 mm) package). This digital IC includes GPIO, communication interfaces (UART, SPI, I2C), and power pins. Refer to the manufacturer datasheet for alternate pin functions and configuration options. Essential for embedded system design and PCB layout.
No detailed pinout data available for ATMEGA325A-AN.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA325A-AN is suitable for 6 applications: Industrial Control Panels, Metering and Data Acquisition, Appliance and Motor Control, Sensor Front-End Systems, Embedded Educational and Maker Platforms, Networking and Communication Accessories.
Industrial Control Panels
The ATMEGA325A-AN fits industrial control panels where its -40C to +105C rating survives hot enclosures and its 54 GPIO lines drive relays, indicators, and keypads directly. The 32 KB Flash stores control logic plus Modbus-style UART protocols, while the 10-bit ADC reads analog setpoint potentiometers and sensor loops without external converters. In a typical panel, the MCU polls digital inputs, executes a state machine, and drives outputs over SPI-isolated drivers; the 20 MHz single-cycle RISC core gives deterministic scan times. Because industrial noise environments stress signal integrity, designers pair the internal oscillator with watchdog supervision and hardware UART framing checks for robust long-term operation.
Recommended
Metering and Data Acquisition
Energy meters, water meters, and environmental dataloggers benefit from the ATMEGA325A-AN's integrated 10-bit ADC, 1 KB EEPROM for calibration constants and usage logs, and 2 KB SRAM for sample buffers. The EEPROM retains data across power cycles without external NVRAM, reducing BOM cost. A typical metering chain connects current/voltage sensor front ends to the ADC channels, accumulates readings in SRAM, and periodically commits aggregates to EEPROM; the UART uploads data to a host. Running the ADC with reduced clock speed improves effective resolution through oversampling, a common technique enabled by the flexible AVR clock prescaler.
Recommended
Appliance and Motor Control
Home appliances - washers, cooktops, HVAC controllers - use the ATMEGA325A-AN for its combination of PWM-capable timers, 54 I/O for user interfaces, and wide 105C temperature tolerance near heat sources. Timer outputs generate PWM for triac firing or fan speed control, while the analog comparator supports zero-cross detection for phase-angle control. The 20 MHz core executes PID loops for temperature regulation with ample margin. Designers must observe creepage and isolation rules between the MCU domain and mains side, typically using optocoupled feedback; the MCU's generous I/O count accommodates button matrices, displays, and buzzer drive on one package.
Recommended
Sensor Front-End Systems
Multi-sensor nodes exploit the ATMEGA325A-AN's 8-channel 10-bit ADC to digitize temperature, humidity, pressure, and current signals without an external ADC. The 64-TQFP's abundant GPIO configures sensor enable lines, multiplexers, and alert interrupts, while SPI connects external high-resolution converters when 10 bits prove insufficient. With an internal oscillator, the entire acquisition node runs crystal-free, saving board area and BOM cost. Data flows over UART or SPI to a gateway; the 2 KB SRAM buffers burst samples between transmissions. For battery-operated nodes, firmware duty-cycles the ADC and peripherals, although the picoPower ATMEGA325PA is preferable where sleep current dominates.
Recommended
Embedded Educational and Maker Platforms
The ATMEGA325A-AN is a natural fit for training boards and maker platforms because the AVR architecture is extensively documented, supported by free toolchains (AVR-GCC, Microchip Studio), and programmable over simple SPI ISP headers. The 54 I/O lines allow students to build seven-segment displays, keypads, stepper motor drivers, and LCD interfaces on a single MCU, teaching both digital and analog interfacing. The 32 KB Flash accommodates bootloader plus substantial coursework code, and read-while-write self-programming enables bootloader-based lab exercises. Its through-lifecycle availability from major distributors keeps education inventory stable semester after semester.
Recommended
Networking and Communication Accessories
Serial-device bridges, protocol converters, and access-control terminals leverage the ATMEGA325A-AN's hardware USART and SPI to translate between field buses and host systems. The 20 MHz core sustains sustained UART traffic at 115200 baud with protocol parsing in C, while hardware flow-control lines are available among the 54 GPIOs. Firmware stored in 32 KB Flash includes buffering state machines, and the 2 KB SRAM handles ring buffers for message queuing. The -40C to +105C rating suits outdoor gateways and rooftop equipment. Designers typically add an external RS-485 transceiver on the UART and use the ADC channel for supply-voltage supervision, reporting brownouts to the host.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA325A-AN — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA325A-AU | ATMEGA325PA-AU | ATMEGA3250A-AU | ATMEGA3250P-20AU |
|---|---|---|---|---|---|
| Package | 64-TQFP (14x14 mm) | 64-TQFP (14x14 mm) - same | 64-TQFP (14x14 mm) - same | 64-TQFP (14x14 mm) - same | 64-TQFP (14x14 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 32 KB Flash | 32 KB Flash | 32 KB Flash | 32 KB Flash | 32 KB Flash |
| Max Clock Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| SRAM / EEPROM | 2 KB / 1 KB | 2 KB / 1 KB | 2 KB / 1 KB | 2 KB / 1 KB | 2 KB / 1 KB |
| GPIO Count | 54 | 54 | 54 | 69 | 69 |
| JTAG Debug | No | No | No | Yes | Yes |
| Low-Power Sleep (picoPower) | No | No | Yes | No | Yes |
Key Differentiators
- Extended 105C industrial temperature rating (vs ATMEGA325A-AU)
- Highest clock performance in the family tier (vs ATMEGA325-16AU)
- Cost-optimized I/O allocation (vs ATMEGA3250A-AU)
Design Notes
Decouple each VCC pin with a 100 nF ceramic capacitor placed within 5 mm of the pin, plus one 4.7 uF to 10 uF bulk capacitor near the 64-TQFP package. The AVR core tolerates moderate supply ripple, but ADC accuracy degrades with noisy AVCC - connect AVCC to a clean supply through an LC filter (10 uH inductor plus 100 nF) when 10-bit ADC precision matters. Estimated: at 20 MHz and 5V, active current consumption is on the order of 10-15 mA per typical AVR datasheet figures, so supply design is straightforward; verify against the official datasheet current tables for your exact clock configuration.
The 64-TQFP (14x14 mm) footprint uses 0.5 mm pin pitch - specify a solder-mask-defined land pattern per IPC-7351 and ensure the reflow profile suits the exposed-frame lead finish. Route the RESET trace short and add a 10 kohm pull-up plus optional 100 nF cap for noise immunity in industrial environments; a spurious reset during Flash write corrupts EEPROM content. Provide ISP header access (MOSI, MISO, SCK, RESET, VCC, GND) on production boards for in-field firmware updates without desoldering the device.
The 2 KB SRAM is the most common capacity pitfall: enable linker check for stack-heap collision, and avoid large sprintf buffers or deep call chains with C libraries. When using the internal RC oscillator, remember UART baud rates drift with temperature - enable two-stop-bit framing or use an external crystal for reliable 115200 baud over the full -40C to +105C range. Also configure unused I/O as inputs with pull-ups or outputs low to prevent floating-pin EMI and excess quiescent current in the 54-pin port matrix.
Estimated: the ATmega core at 20 MHz and 5V dissipates roughly 50-75 mW (10-15 mA at 5V), well within the TQFP-64 natural-convection capability, so no heatsink is needed for typical operation. However, sustained I/O sourcing near maximum per-pin limits across many pins can raise die temperature in sealed enclosures rated to +105C ambient; totalize I/O current budget and keep junction temperature margin per the official datasheet absolute maximum and thermal resistance tables.
Compliance Information
RoHS compliant and lead free per distributor TrustCompo listing ('RoHS-compliant, lead-free, green electronic components'). REACH, halogen-free, and conflict-minerals declarations should be confirmed via Microchip's official compliance portal for the exact date code.