ATMEGA328-MUR - AVR 8-Bit MCU 32KB 20MHz VQFN-32 | Microchip
MPN: ATMEGA328-MUR β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.85 | $2.85 |
| 10 | $2.56 | $25.60 |
| 100 | $2.28 | $228.00 |
| 500 | $2.05 | $1,025.00 |
| 1,000 | $1.84 | $1,840.00 |
ATMEGA328-MUR Overview
An 8-bit AVR microcontroller is a self-contained computing IC that executes programs from internal Flash memory while integrating SRAM, EEPROM, timers, ADC, and communication peripherals on a single die. Within the power-management and embedded-control hierarchy, the ATmega328 sits in the mid-range of Microchip's AVR ATmega family between the ATmega168 (16KB) and the ATmega328PB (enhanced peripheral set), and is the silicon family behind the classic Arduino UNO.
Key features include 131 powerful RISC instructions with mostly single-cycle execution delivering up to 20 MIPS at 20MHz, an 8-channel 10-bit ADC, 2 x 8-bit and 1 x 16-bit timers, and USART, SPI, and I2C (TWI) serial interfaces. The 4K byte self-programming Flash enables boot-loader firmware updates in the field.
Technically, the advanced RISC architecture combines a 32-register general-purpose file directly connected to the ALU, allowing two independent registers to be accessed in a single instruction.debugWIRE on-chip debug support and pin-selectable brown-out detection simplify development and improve system robustness. The device operates from 2.5V to 5.5V depending on speed grade, with sleep modes down to microamp-level standby.
Typical applications include industrial sensors and controllers, Arduino-compatible hobby and maker boards, HVAC and building automation nodes, and battery-powered portable instruments where a mature, well-documented 8-bit platform is preferred.
Design consideration: at 20MHz the device requires 4.5V to 5.5V supply; use the internal 8MHz RC oscillator or an external crystal with appropriate fuse settings, and verify brown-out threshold against supply tolerance.
This page synthesizes distributor pricing context, drop-in alternatives, pinout data, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA328-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 ATMEGA328-MUR (same form factor and footprint) β differing in Package, RoHS Status, Operating Temperature, Supply Voltage Range, Timers.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA328P-MUR
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA328PB-MU
β Drop-Inβ In Stock
$1.19 / Unit
View Datasheet βATMEGA168PA-MU
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$1.72 / Unit
View Datasheet βATMEGA168PB-MU
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$1.31 / Unit
View Datasheet βATMEGA168A-MU
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$1.38 / Unit
View Datasheet βATMEGA328-MUR Maximum Ratings & Electrical Characteristics
| Core Processor | AVR 8-bit RISC |
| Core Size | 8-Bit |
| Speed | 20 MHz |
| Flash Memory Size | 32 KB (16K x 16) |
| SRAM Size | 2 KB |
| EEPROM Size | 1 KB |
| Supply Voltage Range | 2.5 V to 5.5 V (speed dependent) |
| Number of I/O | 23 |
| ADC Resolution | 10 bit |
| ADC Channels | 8 (6 external + 2 extra on QFN) |
| Peripherals | Brown-out Detect/Reset, POR, PWM, WDT, debugWIRE |
| Communication Interfaces | USART, SPI, I2C (TWI) |
| Timers | 2 x 8-bit, 1 x 16-bit |
| Instructions | 131 instructions, mostly single-cycle |
| Throughput | Up to 20 MIPS at 20 MHz |
| Operating Temperature | -40C to +85C (Industrial) |
| Package | 32-VQFN (5x5 mm) Exposed Pad |
| Mounting Type | Surface Mount |
| Packaging | Tape & Reel (R suffix), Green |
| Lifecycle Stage | ACTIVE |
ATMEGA328-MUR Pin Configuration
| Pin 1 | PD3 (PCINT19/OC2B/INT1) β Port D bit 3 / pin change interrupt / Timer2 output compare B / external interrupt 1 |
| Pin 2 | PD4 (PCINT20/XCK/T0) β Port D bit 4 / USART external clock / Timer0 clock input |
| Pin 3 | GND β Ground |
| Pin 4 | VCC β Digital supply voltage |
| Pin 5 | GND β Ground |
| Pin 6 | VCC β Digital supply voltage |
| Pin 7 | PB6 (PCINT6/XTAL1/TOSC1) β Port B bit 6 / crystal oscillator input or Timer oscillator input |
| Pin 8 | PB7 (PCINT7/XTAL2/TOSC2) β Port B bit 7 / crystal oscillator output |
| Pin 9 | PD5 (PCINT21/OC0B/T1) β Port D bit 5 / Timer0 output compare B / Timer1 clock input |
| Pin 10 | PD6 (PCINT22/OC0A/AIN0) β Port D bit 6 / Timer0 output compare A / analog comparator positive input |
| Pin 11 | PD7 (PCINT23/AIN1) β Port D bit 7 / analog comparator negative input |
| Pin 12 | PB0 (PCINT8/CLKO/ICP1) β Port B bit 0 / system clock output / Timer1 input capture |
| Pin 13 | PB1 (PCINT9/OC1A) β Port B bit 1 / Timer1 output compare A (PWM) |
| Pin 14 | PB2 (PCINT10/OC1B/SS) β Port B bit 2 / Timer1 output compare B / SPI slave select |
| Pin 15 | PB3 (PCINT11/OC2A/MOSI) β Port B bit 3 / Timer2 output compare A / SPI master data out |
| Pin 16 | PB4 (PCINT12/MISO) β Port B bit 4 / SPI master data in |
| Pin 17 | PB5 (PCINT13/SCK) β Port B bit 5 / SPI serial clock |
| Pin 18 | AVCC β ADC supply voltage |
| Pin 19 | ADC6 β ADC input channel 6 (QFN/TQFP packages only) |
| Pin 20 | AREF β ADC analog reference |
| Pin 21 | GND β Ground |
| Pin 22 | ADC7 β ADC input channel 7 (QFN/TQFP packages only) |
| Pin 23 | PC0 (PCINT16/ADC0) β Port C bit 0 / ADC channel 0 |
| Pin 24 | PC1 (PCINT17/ADC1) β Port C bit 1 / ADC channel 1 |
| Pin 25 | PC2 (PCINT18/ADC2) β Port C bit 2 / ADC channel 2 |
| Pin 26 | PC3 (PCINT19/ADC3) β Port C bit 3 / ADC channel 3 |
| Pin 27 | PC4 (PCINT20/ADC4/SDA) β Port C bit 4 / ADC channel 4 / I2C data |
| Pin 28 | PC5 (PCINT21/ADC5/SCL) β Port C bit 5 / ADC channel 5 / I2C clock |
| Pin 29 | PC6 (PCINT22/RESET) β Reset input / Port C bit 6 (fuse selectable) |
| Pin 30 | PD0 (PCINT24/RXD) β Port D bit 0 / USART receive data |
| Pin 31 | PD1 (PCINT25/TXD) β Port D bit 1 / USART transmit data |
| Pin 32 | PD2 (PCINT26/INT0) β Port D bit 2 / external interrupt 0 |
Typical Applications
ATMEGA328-MUR is suitable for 6 applications: Arduino-Compatible Maker Boards, Industrial Sensor Nodes, Building Automation and HVAC Controls, Battery-Powered Portable Instruments, Embedded IoT Edge Devices, Motor Control and PWM Actuation.
Arduino-Compatible Maker Boards
The ATMEGA328-MUR is the silicon at the heart of the classic Arduino UNO ecosystem: the same AVR core, 32KB Flash, and 2KB SRAM run all standard Arduino bootloaders and sketches without modification. In commercialized SMD products derived from Arduino reference designs, the industrial-grade, VQFN-32 Tape & Reel packaging enables automated assembly, unlike the DIP parts used in hobby boards. Running a 16MHz crystal at 5V reproduces exact UNO timing, and the debugWIRE on-chip debug facility plus wide ISP tool support keep development friction minimal across prototype-to-production transitions.
Recommended
Industrial Sensor Nodes
With its 8-channel 10-bit ADC, brown-out detection, watchdog timer, and -40C to +85C industrial temperature rating, the ATMEGA328-MUR suits factory sensor and monitoring nodes. The 10-bit ADC samples up to 15kSPS for temperature, pressure, and voltage channels, while the 1KB EEPROM stores calibration coefficients through power cycles. The 5V-tolerant I/O simplifies interfacing with industrial 5V logic, and sleep modes support periodically-waking battery-assisted sensors. Its 20MHz throughput handles local filtering and Modbus-over-UART communication with SCADA masters, making it a robust, well-understood choice for brownfield 8-bit control retrofits.
Recommended
Building Automation and HVAC Controls
HVAC dampers, thermostats, and zone controllers benefit from the ATMEGA328-MUR's combination of I2C/TWI for sensor buses, SPI for external memory or displays, and a full-duplex USART for RS-485 field communication. The 1KB EEPROM retains setpoints and schedules without external NVM, and the pin-change interrupts on all 23 I/O lines allow button wake-up from deep sleep. Brown-out reset with selectable threshold protects configuration data during brownouts on mains-derived supplies, and the 4KB self-programming boot section permits field firmware updates over the existing UART, cutting service costs in installed-base equipment.
Recommended
Battery-Powered Portable Instruments
Although not the lowest-power MCU available, the ATMEGA328-MUR's sleep architecture - power-down at well under 10uA class currents on the picoPower sibling and active currents in the low-mA range at reduced clocks - supports handheld meters, loggers, and testers with duty-cycled operation. The internal 8MHz RC oscillator removes crystal cost for non-timing-critical applications, and operating down to 2.5V lets the MCU drain two AA cells or a single Li coin cell through an LDO efficiently. The 10-bit ADC reads battery voltage and sensor inputs, while the watchdog guarantees recovery from stalled firmware in unattended field use.
Recommended
Embedded IoT Edge Devices
For simple IoT endpoints bridging local sensors to a Wi-Fi or LoRa module, the ATMEGA328-MUR provides a deterministic 8-bit control plane with USART and SPI links to connectivity modules. Its 20 MIPS throughput comfortably handles AT-command protocols, CRC checks, and sensor fusion pre-processing, while mature open-source toolchains shorten firmware development. The exposed-pad VQFN-32 offers good thermal and ground behavior on small PCBs, and Tape & Reel packing suits contract manufacturing. Designers should offload TLS and heavy crypto to the radio module, as the 2KB SRAM cannot host a full TCP/IP stack locally.
Recommended
Motor Control and PWM Actuation
The three timers of the ATMEGA328-MUR generate up to six hardware PWM channels: the 16-bit Timer1 provides high-resolution servo and motor PWM, while the two 8-bit timers drive fans, LED dimming, and H-bridge direction logic through the Fast PWM and phase-correct modes. Input-capture and analog-comparator peripherals enable back-EMF sensing for sensorless fan speed regulation. Combined with an external gate driver, this makes the device a compact controller for small DC motors in appliances, pumps, and Robotics hobby platforms, with the ADC reading current shunts for basic stall detection and closed-loop speed regulation.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA328-MUR β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA328P-MUR | ATMEGA328PB-MU | ATMEGA168PA-MU |
|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 32-VQFN (5x5) EP | 32-VQFN (5x5) EP - same | 32-VQFN (5x5) EP - same | 32-VQFN (5x5) EP - same |
| Flash Memory | 32 KB | 32 KB | 32 KB | 16 KB |
| SRAM | 2 KB | 2 KB | 2 KB | 1 KB |
| EEPROM | 1 KB | 1 KB | 1 KB | 512 B |
| Max Clock Speed | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| USART Count | 1 | 1 | 2 | 1 |
| Sleep-Mode Power (picoPower) | Standard die | picoPower - lowest | picoPower - lowest | picoPower - lowest |
| Pin Compatibility Notes | Reference | Full pin-to-pin drop-in | Drop-in except pins 3 and 6 | Full pin-to-pin drop-in |
Key Differentiators
- Largest Flash in the base pin-compatible family (vs ATMEGA168PA-MU)
- True pin-to-pin compatibility with legacy designs (vs ATMEGA328PB-MU)
- Industrial temperature and Tape & Reel for automated assembly (vs ATMEGA328P-PU (DIP version))
- Trade-off: higher sleep current than picoPower variants (vs ATMEGA328P-MUR)
Design Notes
Clock-speed grade depends on VCC: full 20MHz operation requires 4.5V to 5.5V per the datasheet speed-vs-voltage curve; at 3.3V derate to about 13-14MHz maximum. Enable the brown-out detector with a threshold (e.g., 2.7V or 4.3V class) matched to your supply so EEPROM writes and flash self-programming abort safely during brownouts - programming operations below the minimum safe voltage can corrupt memory. Decouple each VCC pin (4 and 6) and AVCC (18) with 100nF ceramic capacitors placed within 5mm of the pins.
The exposed pad on the 32-VQFN must be soldered to a ground-plane tied array of vias - it is both the primary thermal relief and a mandatory ground return. Connect AVCC to VCC through an LC or RC filter (e.g., 10uH ferrite plus 100nF) when ADC accuracy matters, and route analog traces away from the SPI clock. Keep the AREF node with a 100nF capacitor to ground; never connect AREF directly to an external reference without removing the internal-reference fuse configuration.
Fuse settings are the most common source of field failures: a wrong clock-source fuse (e.g., external clock selected with a crystal installed) bricks the ISP interface and requires a high-voltage parallel programmer or clock-injection recovery. Always set the lock and fuse bits via ISP or debugWIRE with verified settings, and keep CKOUT (PB0) disabled unless needed. When migrating to ATMEGA328PB-MU, note pins 3 and 6 function differences per Microchip application guidance - verify those nets are unused before swapping.
Estimated: at 5V, 20MHz, and typical 10-15mA active current, power dissipation is roughly 50-75mW including I/O loads, producing only a few degrees C junction rise over ambient with the exposed pad grounded - no heatsinking is needed. Thermal attention is only required if many I/O pins source/sink the 20-40mA absolute-max currents continuously; keep per-pin DC currents at or below 20mA rated conditions to protect the port structures.
Compliance Information
Distributor data lists the part as Green packaging with lifecycle stage ACTIVE. REACH and conflict-minerals declarations not stated in provided data.
