ATMEGA325A-MN - 8-bit AVR MCU 32KB Flash 20MHz QFN-64 | Microchip
MPN: ATMEGA325A-MN ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.88 | $4.88 |
| 10 | $4.39 | $43.90 |
| 100 | $3.91 | $391.00 |
| 500 | $3.52 | $1,760.00 |
| 1,000 | $3.17 | $3,170.00 |
ATMEGA325A-MN Overview
A microcontroller (MCU) is a single-chip computer that integrates a processor core, program memory, data memory, and peripherals such as timers, USART, SPI, and ADC on one die. Microcontrollers form the foundation of embedded systems, sitting at the lowest level of the computing hierarchy above discrete logic and below application processors. The AVR ATmega family from Microchip (formerly Atmel) is one of the most widely deployed 8-bit MCU families in industrial and consumer electronics.
Key features of the ATMEGA325A include 130 powerful RISC instructions, most executing in a single clock cycle, 32 general-purpose working registers, read-while-write Flash for in-system self-programming, an on-chip JTAG interface for boundary-scan and on-chip debugging, and 54 general-purpose I/O lines in the 64-pin package. The internal RC oscillator removes the need for an external crystal in many designs, while the enhanced peripherals include an 8-channel 10-bit ADC, USART, SPI, and two 8-bit plus two 16-bit timers with PWM.
The ATMEGA325A is fabricated on an updated process relative to the original ATmega325; per Microchip application note AVR540, it is a functionally identical drop-in replacement for the ATmega325, though some electrical characteristics differ because of the new process. A 105C temperature grade (MN suffix) suits industrial environments.
Typical applications include industrial control panels, building automation nodes, consumer appliances, LED lighting controllers, and instrumentation front ends where the 10-bit ADC, rich timer complement, and generous 54 I/O count allow single-chip designs.
When designing, keep the 20MHz clock ceiling in mind - derating the clock allows lower-voltage operation for battery-powered products, following the standard AVR speed-versus-voltage curves.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA325A-MN — 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-MN (same form factor and footprint) — differing in Package, Operating Temperature, EEPROM Size, Programmability, Debug Interface.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA325A-MNR
✅ Drop-In✓ In Stock
$1.55 / Unit
View Datasheet →ATMEGA3250A-MN
✅ Drop-In ⚠️ 参数待验证✓ In Stock
Contact for price
View Datasheet →ATMEGA325-16MI
✅ Drop-In✓ In Stock
$3.05 / Unit
View Datasheet →ATMEGA325V-8MU
✅ Drop-In✓ In Stock
$3.9 / Unit
View Datasheet →ATMEGA64A-MU
✅ Drop-In✓ In Stock
$4.24 / Unit
View Datasheet →ATMEGA325A-MN Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Program Memory Size | 32 KB (16K x 16) Flash |
| Program Memory Type | ISP Flash (read-while-write) |
| SRAM Size | 2 KB (2K x 8) |
| EEPROM Size | 1 KB |
| Maximum Clock Speed | 20 MHz |
| Number of I/O | 54 |
| General Purpose Working Registers | 32 |
| Instruction Set | 130 instructions, most single-cycle |
| Debug Interface | JTAG (boundary scan + on-chip debug) |
| Oscillator Type | Internal RC |
| Package / Case | 64-VFQFN Exposed Pad (9x9 mm) |
| Operating Temperature | -40C to +105C |
| Mounting Style | Surface Mount |
| Packaging | Tube |
ATMEGA325A-MN 64-vfqfn exposed pad (9x9 mm) Pin Configuration Guide
Pin configuration for ATMEGA325A-MN (64-vfqfn exposed pad (9x9 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-MN.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA325A-MN is suitable for 6 applications: Industrial Control Panels, Building Automation Nodes, Consumer Appliance Control Boards, LED Lighting Controllers, Instrumentation and Data Loggers, Motor and Actuator Controllers.
Industrial Control Panels
The ATMEGA325A-MN fits industrial control panels because its 54 GPIO lines drive relays, contactors, status LEDs, and keypads from a single chip, eliminating I/O expanders. The -40C to +105C MN temperature grade withstands panel-mounted enclosures near heat-generating components, and JTAG enables in-field firmware audits and boundary-scan manufacturing tests. In a typical panel, the 20MHz AVR core scans digital inputs, runs a state machine, and updates outputs at kilohertz rates - far beyond requirement - while the internal RC oscillator removes the crystal from the BOM. Use the USART for Modbus RTU links to SCADA; the 1KB EEPROM stores configuration and calibration data across power cycles. The trade-off versus a 32-bit MCU is lower arithmetic throughput, which is rarely a constraint in sequential panel logic.
Recommended
Building Automation Nodes
Building automation sensor and actuator nodes benefit from the ATMEGA325A-MN's combination of low-power AVR sleep modes, an internal RC oscillator, and ample 10-bit ADC channels for temperature, humidity, and occupancy sensor front ends. Nodes typically wake from power-down sleep on a periodic timer, sample the ADC, and transmit status over RS-485 (USART) to a floor controller; battery-powered variants benefit from running at reduced clock frequencies where dynamic power scales down linearly. The 2KB SRAM comfortably buffers protocol frames and sensor-filtering state, while the 1KB EEPROM retains node addressing and calibration. With 54 I/O, one MCU can handle door locks, dampers, and LED indication concurrently. Choose this part when wired RS-485 nodes need rugged 105C operation in ceiling or plenum installations.
Recommended
Consumer Appliance Control Boards
Appliance control boards - washers, ovens, air conditioners - are a classic ATmega325/3250 application domain because they demand dozens of I/O for buttons, seven-segment or LCD displays, triac-driven loads, and feedback switches at consumer-grade cost. The ATMEGA325A-MN's 54 GPIO handles button matrices and LED drive directly, and the same 64-QFN footprint as the LCD-equipped ATMEGA3250A-MN lets one PCB platform serve both display variants. Timer PWM outputs generate mains-phase-control waveforms for heater and motor power regulation, while the 10-bit ADC reads NTC thermistors for over-temperature cutoffs. The 20MHz ceiling provides headroom for push-button debounce, display multiplexing, and safety supervision loops running in parallel interrupt service routines within a straightforward super-loop firmware architecture.
Recommended
LED Lighting Controllers
Dimmable LED fixture controllers use the ATMEGA325A-MN's four timers with PWM outputs to generate 8-bit to 16-bit dimming waveforms for constant-current LED drivers, while the 10-bit ADC monitors supply current and LED temperature via NTC sensors for closed-loop derating. The 105C rating matters because luminaire drivers often reach 85C+ internal ambient, giving comfortable margin. With 54 I/O, one controller can sequence RGBW color mixing, DALI or DMX-512 receive circuitry (USART + external transceiver), and presence-detector inputs simultaneously. The internal RC oscillator's accuracy is adequate for PWM dimming above 1kHz flicker-free rates, avoiding crystal cost; for DMX timing-critical reception, an external crystal is recommended. Firmware complexity stays low since the AVR core easily sustains multi-channel PWM refresh at 20MHz.
Recommended
Instrumentation and Data Loggers
Bench and field instrumentation front ends leverage the ATMEGA325A-MN's 8-channel 10-bit ADC for multi-point voltage, current, and temperature acquisition, with the 32KB Flash storing lookup tables, linearization curves, and menu-driven UI code. The JTAG interface is particularly valuable in instrumentation: engineers use on-chip debugging to trace measurement state machines through calibration routines and boundary scan to validate board assembly. Sampled data buffers in the 2KB SRAM before being offloaded through the USART to a PC or written with timestamps derived from Timer1; calibration constants persist in the 1KB EEPROM. Long-term logging benefits from power-down sleep between samples, stretching battery life in portable meters. For higher-resolution needs, pair the MCU with an external 16-bit ADC over its SPI bus.
Recommended
Motor and Actuator Controllers
The ATMEGA325A-MN suits small DC motor and actuator controllers: two 8-bit and two 16-bit timers generate complementary PWM with dead-time-capable channels for H-bridge drives, while external interrupt pins capture quadrature encoder pulses for closed-loop position control. The 10-bit ADC reads motor current through a sense resistor for stall detection and torque limiting, and the 54 I/O count supports limit switches, indicator stacks, and a CAN or RS-485 interface transceiver simultaneously. Running the core at 20MHz permits kilohertz-rate current-loop interrupt service without starving the supervisory loop. The 105C MN grade is appropriate for actuator housings that heat up under duty cycles. Designers should budget SRAM carefully (2KB) when implementing PID state plus communication buffers, and consider the ATMEGA64A-MU if filter histories grow.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA325A-MN — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA325A-MNR | ATMEGA3250A-MN | ATMEGA325-16MI | ATMEGA64A-MU |
|---|---|---|---|---|---|
| Package | 64-VFQFN (9x9 mm) Exposed Pad | 64-VFQFN (9x9 mm) - same | 64-VFQFN (9x9 mm) - same | 64-MLF (9x9 mm) - same footprint | 64-QFN (9x9 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 32 KB | 32 KB | 32 KB | 32 KB | 64 KB |
| SRAM | 2 KB | 2 KB | 2 KB | 2 KB | 4 KB |
| Max Clock Speed | 20 MHz | 20 MHz | 20 MHz | 16 MHz | 16 MHz |
| General Purpose I/O | 54 | 54 | 54 (shared with LCD pins) | 54 | 54 |
| Operating Temperature | -40C to +105C | -40C to +105C | -40C to +105C | -40C to +85C | -40C to +85C |
| Special Features | JTAG, internal RC oscillator | JTAG, internal RC oscillator | Adds LCD segment driver | JTAG, legacy process | JTAG, 2x memory |
Key Differentiators
- 20MHz operation versus 16MHz legacy parts (vs ATMEGA325-16MI)
- Package-only variant flexibility (vs ATMEGA325A-MNR)
- Same-footprint LCD upgrade path (vs ATMEGA3250A-MN)
Design Notes
The AVR family enforces a maximum clock frequency versus supply voltage relationship: to run at 20MHz the device must operate in the highest voltage bucket, and lower-voltage operation requires derating the clock. Consult the speed-versus-voltage curve in the ATmega325A datasheet electrical characteristics before fixing your regulator output. Estimated: running at half frequency roughly halves dynamic core current, so battery designs should start at the lowest clock that meets timing deadlines. Decouple VCC and AVCC separately with 100nF ceramics placed within 5mm of each pin pair.
The 64-VFQFN exposed pad is the primary ground and thermal path. Connect the exposed pad to a solid ground plane through a 4x4 or 5x5 via array (0.3mm vias) under the die - a solder mask-defined landing pattern per Microchip's QFN layout guidelines improves paste coverage. Route the JTAG (TCK, TMS, TDO, TDI) as a header even if unused in production; boundary-scan test coverage at ICT pays back the two-cent header cost. Keep the RESET line below 10cm with a 10k pullup for reliable external programmer attachment.
Do not assume the ATmega325A is electrically identical to the original ATmega325: application note AVR540 states it is functionally identical but process-related electrical characteristics differ - re-verify worst-case timing, oscillator calibration, and current consumption against the new datasheet when porting legacy designs. Also remember the 105C MN grade does not extend the 20MHz clock ceiling; check that your operating point satisfies both temperature and frequency-voltage constraints simultaneously. Finally, if migrating from a TQFP version to the QFN, verify peripheral pin mapping before reusing firmware pin definitions.
Compliance Information
Microchip lists the MN variant as Green (RoHS-compliant, lead-free) in distributor listings (FindIC: 'MLF/QFN, 105C, Green'). REACH and halogen-free status not stated in sourced data.
