ATMEGA325PA-MUR - 8-bit AVR MCU 32KB 20MHz 64-QFN | Microchip
MPN: ATMEGA325PA-MUR β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.23 | $2.23 |
| 10 | $2.06 | $20.60 |
| 100 | $1.91 | $191.00 |
| 500 | $1.78 | $890.00 |
| 1,000 | $1.65 | $1,650.00 |
ATMEGA325PA-MUR Overview
An 8-bit microcontroller integrates a processor core, memory, and peripherals on a single chip, forming the lowest tier of the embedded-processor hierarchy (MCU -> embedded processor -> semiconductor). AVR is a modified Harvard architecture with mostly single-cycle instruction execution, making it a popular alternative to PIC16-class and 8051-class MCUs for cost-sensitive embedded control.
Key features include picoPower technology for ultra-low active and sleep current, an 8-channel 10-bit ADC, a JTAG interface for on-chip debugging and boundary scan, and wide 1.8V to 5.5V single-supply operation. The 131-instruction AVR core executes most instructions in a single clock cycle, and 32 general-purpose working registers keep interrupt latency low.
Architecturally, the self-programming Flash allows in-system firmware updates via boot-loader code, while the separate EEPROM retains calibration data through power cycles. Advanced power-management modes (idle, power-save, power-down, standby) let designers trade wake-up latency against microamp-level sleep current, a hallmark of the picoPower A-series silicon.
Typical applications include industrial sensor nodes, consumer appliance control panels, battery-powered metering, and HVAC/LCD user interfaces where a rich I/O count and ADC channels are required in a compact 9x9 mm footprint.
A key design consideration is supply-voltage-dependent maximum clock speed: at 1.8V the safe operating frequency is derated substantially below 20 MHz, so consult the frequency-versus-voltage curve in the manufacturer datasheet before finalizing the oscillator design.
This page synthesizes distributor pricing, verified drop-in alternatives within the AVR family, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for ATMEGA325PA-MUR 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 ATMEGA325PA-MUR (same form factor and footprint) β differing in Package, RoHS Status, Operating Temperature, Maximum Clock Frequency, Flash Memory.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA325P-20MUR
β Drop-Inβ In Stock
$2.86 / Unit
View Datasheet βATMEGA325-16MI
β Drop-Inβ In Stock
$3.05 / Unit
View Datasheet βATMEGA329P-20MUR
β Drop-Inβ In Stock
$5.4 / Unit
View Datasheet βATMEGA3250PA-MUR
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA645P-20MUR
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA325PA-MUR Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Flash Program Memory | 32 KB (16K x 16) |
| SRAM | 2 KB |
| EEPROM | 1 KB |
| Maximum Clock Frequency | 20 MHz |
| Peak Throughput | 20 MIPS at 20 MHz |
| Supply Voltage Range | 1.8 V to 5.5 V |
| ADC | 8-channel 10-bit |
| Debug Interface | JTAG (on-chip debug, boundary scan) |
| Low-Power Technology | picoPower |
| Package | 64-QFN (MLF) 9x9 mm, exposed pad |
| Mounting Type | Surface Mount |
| Temperature Range | Industrial |
| Instructions | 131 powerful instructions, most single-cycle |
| Packaging / Reeling | Tape & Reel (R suffix), GREEN |
| RoHS Status | Compliant (GREEN package) |
ATMEGA325PA-MUR 64-qfn (mlf) 9x9 mm, exposed pad Pin Configuration Guide
Pin configuration for ATMEGA325PA-MUR (64-qfn (mlf) 9x9 mm, exposed pad 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 ATMEGA325PA-MUR.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA325PA-MUR is suitable for 6 applications: Industrial Sensor Nodes, Battery-Powered Metering, Appliance Control Panels, HVAC and Building Automation, Portable Instrumentation, Embedded Control Retrofits.
Industrial Sensor Nodes
The ATMEGA325PA-MUR suits industrial sensor nodes because its 8-channel 10-bit ADC digitizes multiple analog sensors (pressure, temperature bridge, potentiometer) without an external converter, while 1.8-5.5 V operation tolerates unregulated 24 V-bus-derived or battery supplies. The picoPower A-series die reduces active-mode current, extending life in duty-cycled nodes that sleep in power-down between samples. Placed as the main controller with SPI/I2C peripherals and JTAG available for field diagnostics, it delivers 20 MIPS headroom for local filtering and protocol handling at 20 MHz; trade-off: 8-bit core limits heavy DSP workloads versus 32-bit alternatives.
Recommended
Battery-Powered Metering
For electricity, water, and heat meters, the ATMEGA325PA-MUR combines microamp-class picoPower sleep modes with the 1 KB EEPROM needed to store cumulative register and calibration data through power cycles. The 10-bit ADC samples shunt or CT inputs, and the asynchronous timer keeps an RTC alive in power-save mode. Operating directly from 1.8-5.5 V battery stacks removes a regulator stage, cutting quiescent drain. Firmware self-programming in the 32 KB Flash enables sealed-unit tariff updates over the communication link; the main consideration is scheduling ADC bursts from sleep to keep average consumption within the battery budget.
Recommended
Appliance Control Panels
Appliance user interfaces need many I/O for keys, LEDs, and relays - exactly what the 64-pin ATMEGA325PA-MUR provides, with generous port width and the 10-bit ADC for NTC temperature sensing in ovens and refrigerators. Industrial temperature rating and 5 V tolerant operation align with appliance power rails, while the 9x9 mm MLF keeps the controller footprint small on cost-driven single-sided-dense PCBs. The JTAG interface supports production-line boundary-scan testing of board assembly. Use the internal RC oscillator to eliminate a crystal and its cost; reserve the external crystal only where timing accuracy for communications demands it.
Recommended
HVAC and Building Automation
In HVAC controllers and damper/valve actuators, the ATMEGA325PA-MUR reads multiple NTC sensors through its 8-channel ADC and drives triacs, relays, and stepper valves from its wide port set. The 1.8-5.5 V range accepts transformer-derived supplies, and picoPower sleep modes cut standby draw in always-plugged equipment where standby legislation applies. At 20 MHz the AVR core comfortably runs PID loops and Modbus/UART communication simultaneously. Designers should budget RC-oscillator tolerance for UART timing or fit a crystal, and use the EEPROM for setpoint persistence across outages - both standard patterns in Microchip's AVR reference designs.
Recommended
Portable Instrumentation
Handheld instruments benefit from the ATMEGA325PA-MUR's 1.8 V minimum supply, which runs directly from two NiMH or alkaline cells down to end-of-discharge, and from picoPower power-down mode that preserves battery between measurements. The 10-bit ADC with internal reference handles transducer front ends, while 32 KB Flash accommodates menu systems, calibration tables, and logging firmware. JTAG enables firmware development on the actual handheld board without sockets. Placed with an SPI display and MEMS sensors, the part delivers responsive 20 MIPS interactive performance; the key trade-off is the MLF package's rework difficulty in low-volume prototypes, mitigated by hot-plate assembly.
Recommended
Embedded Control Retrofits
Legacy AVR designs based on the ATmega325/3250 non-picoPower generations can be refreshed to the ATMEGA325PA-MUR without PCB changes, gaining lower active and sleep current in the identical 64-QFN footprint and keeping the same AVR Studio toolchain and ISP programming fixtures. This makes it a natural modernization drop for service parts and long-lifecycle industrial equipment. Firmware written for the earlier die runs unchanged in nearly all cases, with only fuse and signature-byte housekeeping required. Engineering effort is limited to a validation run; the payoff is reduced standby power and continued factory support on an active lifecycle status.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA325PA-MUR β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA325P-20MUR | ATMEGA325-16MI | ATMEGA329P-20MUR | ATMEGA645P-20MUR |
|---|---|---|---|---|---|
| Package | 64-QFN (MLF) 9x9 mm | 64-QFN (MLF) 9x9 mm - same | 64-QFN (MLF) - same | 64-QFN (MLF) - same | 64-QFN (MLF) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash | 32 KB | 32 KB | 32 KB | 32 KB | 64 KB |
| Max Clock | 20 MHz | 20 MHz | 16 MHz | 20 MHz | 20 MHz |
| SRAM | 2 KB | 2 KB | 2 KB | 2 KB | 4 KB |
| Low-Power Technology | picoPower (A-series) | picoPower (P die) | No (standard) | picoPower (P die) | picoPower (P die) |
| LCD Driver | No | No | No | Yes (segment LCD) | Yes (segment LCD) |
| Supply Voltage | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 2.7 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V |
| Lifecycle Status | Active | Active | Active | Active | Active |
Key Differentiators
- picoPower A-series die lowers sleep current (vs ATMEGA325P-20MUR)
- Full 1.8-5.5 V operation at 20 MHz rating (vs ATMEGA325-16MI)
- Maximum general-purpose I/O in the family footprint (vs ATMEGA329P-20MUR)
- 32 KB right-sized Flash keeps cost down (vs ATMEGA645P-20MUR)
Design Notes
The 1.8-5.5 V range hides an important constraint: maximum clock frequency is supply-dependent. At 5 V the core runs at 20 MHz, but near 1.8 V the safe frequency is much lower (per the frequency-vs-voltage curve in the manufacturer datasheet). If your application must run 20 MHz at all times, regulate the supply to at least ~4.5 V or use a boost converter; if running from batteries, consider dynamic clock switching between active and sleep phases to combine throughput with picoPower savings.
The 64-QFN MLF package has an exposed die pad that must be soldered to a grounded copper pour. Use a ~3x3 (or larger) via array under the pad to tie it to internal ground planes - this is required for mechanical reliability and aids heat spreading, per Microchip MLF application guidance. For reflow, the pad aperture on the stencil should be patterned (multiple small openings) rather than one large opening to avoid voiding and floating the package.
ATmega325-family MCUs use fuse bytes for clock source, BOD, and JTAG configuration; an incorrect CKSEL fuse selection can brick boards with only ISP access. Set the JTAGEN fuse deliberately: leaving JTAG enabled shares four port pins (JTAG default on) which reduces available I/O if you expected full port width. Verify signature and lock-bit programming on the programming fixture before release builds, and confirm EEPROM preservation settings so field firmware updates do not erase calibration data.
Decouple each VCC/AVCC pin pair with 100 nF ceramics placed within a few millimeters of the pads, plus one bulk 4.7-10 uF per supply domain. Keep the ADC analog supply (AVCC) filtered with an LC or RC network when switching loads (relays, LEDs) share the 5 V rail; ADC reference noise directly appears as code jitter in the 10-bit converter. Route the crystal (if used) short and guarded by ground, away from PWM and relay traces.
Compliance Information
Distributor listings describe the part as GREEN packaging with industrial temperature range, indicating RoHS/lead-free/halogen-free compliance. AEC-Q100 qualification is not claimed in the provided data.
