ATMEGA328P-MU - 8-bit AVR MCU 20MHz 32KB Flash | Microchip
MPN: ATMEGA328P-MU β End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.9 | $1.90 |
| 10 | $1.71 | $17.10 |
| 100 | $1.53 | $153.00 |
| 500 | $1.4 | $700.00 |
| 1,000 | $1.28 | $1,280.00 |
ATMEGA328P-MU Overview
An 8-bit microcontroller (MCU) is a complete computing system on a single chip, combining a CPU core, program memory (Flash), data memory (SRAM), non-volatile data storage (EEPROM), and peripherals such as timers, ADCs, and communication interfaces. Microcontrollers sit at the heart of embedded systems, bridging the gap between simple logic ICs and application processors in the broader semiconductor hierarchy.
Key features of the ATMEGA328P-MU include 131 single-cycle RISC instructions executing up to 20 MIPS at 20MHz, a 10-bit ADC with up to 15 channels (6 on the QFN package plus 2 extra ADC channels), and picoPower technology with multiple sleep modes for battery-powered designs. The P suffix denotes picoPower, delivering very low power consumption in active and idle modes.
Architecturally, the ATmega328P uses an AVR Harvard-architecture RISC core with 32 general-purpose working registers directly connected to the ALU, allowing two independent registers to be accessed in a single instruction executed in one clock cycle. On-chip debugging is supported via debugWIRE, and In-System Programming (ISP) allows firmware updates without removing the chip from the PCB.
Typical applications include Arduino-compatible boards, industrial control, consumer appliances, sensor nodes, and battery-operated instruments. The wide 1.8V to 5.5V operating range makes it well suited to both 3.3V and 5V systems, and the rich timer set (two 8-bit, one 16-bit) supports PWM motor control and precise timing.
Design consideration: at 5V and 20MHz, verify supply decoupling on all VCC/AVCC pins and keep the analog reference (AREF) quiet for accurate 10-bit ADC results.
This page synthesizes distributor pricing, drop-in alternatives, pinout data, and practical design notes not found in a single manufacturer datasheet, as of 2026-09-17.
Drop-in alternatives for ATMEGA328P-MU 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 ATMEGA328P-MU (same form factor and footprint) β differing in Package, Operating Temperature, Timers, Program Memory Size, Communication Interfaces.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA328PB-MUR
β Drop-Inβ In Stock
$1.68 / Unit
View Datasheet βATMEGA328-MUR
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$1.84 / 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 βATMEGA88PA-MU
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA328P-MU Maximum Ratings & Electrical Characteristics
| Core Processor | AVR 8-bit RISC |
| Core Size | 8-bit |
| Speed | 20 MHz |
| Program Memory Size | 32 KB (16K x 16) Flash |
| EEPROM Size | 1 KB |
| RAM Size | 2 KB |
| Number of I/O | 23 |
| Supply Voltage Range | 1.8 V to 5.5 V |
| ADC Resolution | 10-bit |
| ADC Channels | 8 (6 external + 2 multiplexed) |
| Peripherals | Brown-out Detect/Reset, POR, PWM, WDT |
| Communication Interfaces | USART, SPI, I2C (TWI) |
| Timers | 2 x 8-bit, 1 x 16-bit |
| Operating Temperature | -40C to +85C |
| Package | 32-VQFN (5x5 mm) |
| Mounting Type | Surface Mount |
| Programming | ISP, debugWIRE |
| Oscillator Type | Internal |
ATMEGA328P-MU Pin Configuration
| Pin 1 | PD3 (PCINT19/OC2B/INT1) β Port D bit 3, pin change interrupt, PWM output, external interrupt 1 |
| Pin 2 | PD4 (PCINT20/XCK/T0) β Port D bit 4, pin change interrupt, USART 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 |
| 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, PWM output, Timer1 clock input |
| Pin 10 | PD6 (PCINT22/OC0A/AIN0) β Port D bit 6, PWM output, analog comparator positive input |
| Pin 11 | PD7 (PCINT23/AIN1) β Port D bit 7, analog comparator negative input |
| Pin 12 | PB0 (PCINT0/CLKO/ICP1) β Port B bit 0, clock output, Timer1 input capture |
| Pin 13 | PB1 (PCINT1/OC1A) β Port B bit 1, 16-bit Timer1 PWM output A |
| Pin 14 | PB2 (PCINT2/SS/OC1B) β Port B bit 2, SPI slave select, Timer1 PWM output B |
| Pin 15 | PB3 (PCINT3/OC2A/MOSI) β Port B bit 3, PWM output, SPI master out |
| Pin 16 | PB4 (PCINT4/MISO) β Port B bit 4, SPI master in |
| Pin 17 | PB5 (PCINT5/SCK) β Port B bit 5, SPI clock |
| Pin 18 | AVCC β ADC supply voltage |
| Pin 19 | ADC6 β ADC input channel 6 (QFN package) |
| Pin 20 | AREF β Analog reference for ADC |
| Pin 21 | GND β Ground |
| Pin 22 | ADC7 β ADC input channel 7 (QFN package) |
| Pin 23 | PC0 (PCINT8/ADC0) β Port C bit 0, ADC channel 0 |
| Pin 24 | PC1 (PCINT9/ADC1) β Port C bit 1, ADC channel 1 |
| Pin 25 | PC2 (PCINT10/ADC2) β Port C bit 2, ADC channel 2 |
| Pin 26 | PC3 (PCINT11/ADC3) β Port C bit 3, ADC channel 3 |
| Pin 27 | PC4 (PCINT12/SDA/ADC4) β Port C bit 4, I2C data, ADC channel 4 |
| Pin 28 | PC5 (PCINT13/SCL/ADC5) β Port C bit 5, I2C clock, ADC channel 5 |
| Pin 29 | PC6 (PCINT14/RESET) β Reset input, active low (or Port C bit 6 if RSTDISBL fuse set) |
| Pin 30 | PD0 (PCINT16/RXD) β Port D bit 0, USART receive |
| Pin 31 | PD1 (PCINT17/TXD) β Port D bit 1, USART transmit |
| Pin 32 | PD2 (PCINT18/INT0) β Port D bit 2, external interrupt 0 |
Typical Applications
ATMEGA328P-MU is suitable for 6 applications: Arduino-Compatible Boards, Battery-Powered Sensor Nodes, Industrial Control and Automation, Consumer Appliances, Motor Control and PWM Systems, Test and Measurement Instruments.
Arduino-Compatible Boards
The ATmega328P is the MCU at the heart of the classic Arduino Uno and Nano platforms, and the ATMEGA328P-MU brings that proven ecosystem to compact VQFN-32 board designs. Its 32KB Flash holds bootloaders plus generous user sketches, while the 1.8V to 5.5V supply range supports both 3.3V and 5V board variants. The internal 8MHz RC oscillator enables crystal-less low-cost designs, and ISP plus a UART bootloader allows programming without special sockets. Because Arduino core support, fuse presets, and countless tutorials target this exact die, development risk is minimal, making it the default choice for hobbyist and maker product lines.
Recommended
Battery-Powered Sensor Nodes
With picoPower technology and multiple sleep modes, the ATMEGA328P-MU achieves microamp-level standby consumption, which is essential for battery-powered sensor nodes expected to run for months or years. The internal 8MHz oscillator eliminates external clock components, and the 10-bit ADC samples up to 8 channels for temperature, humidity, or voltage monitoring. Operating down to 1.8V allows direct use with two alkaline cells or a single Li-SOCl2 cell through the discharge curve. Designers typically use power-down sleep with watchdog wake intervals; per datasheet guidance, unused GPIOs should be defined as outputs low or inputs with pull-ups to minimize leakage in sleep.
Recommended
Industrial Control and Automation
The ATMEGA328P-MU fits cost-sensitive industrial control nodes with its -40C to +85C rating, brown-out detection, watchdog timer, and power-on reset for reliable autonomous operation. Two 8-bit timers plus one 16-bit timer generate PWM for motor drives, heater control, or valve actuators, while the USART and SPI/I2C interfaces link to drives, HMIs, and field sensors. The 32KB Flash accommodates protocol stacks and parameter tables, and the 1KB EEPROM stores calibration data across power cycles. Field firmware updates are performed in-system through the ISP header, minimizing downtime in installed equipment where board removal is impractical.
Recommended
Consumer Appliances
Consumer appliances such as coffee machines, fans, small pumps, and lighting controllers benefit from the ATMEGA328P-MU's low unit cost, wide 1.8V to 5.5V supply tolerance, and integrated peripherals that reduce bill-of-materials count. The internal oscillator and internal bandgap reference allow fully crystal-less and external-reference-free designs at modest accuracy targets, while PWM outputs drive LEDs and small motors directly through transistors. The VQFN-32 (5x5 mm) package keeps PCB area small for handheld and compact products. Touch-sensing can be implemented in firmware using the ADC, and the 10-bit ADC reads user controls, thermistors, and battery levels.
Recommended
Motor Control and PWM Systems
The ATmega328P timer architecture makes the ATMEGA328P-MU a solid fit for small motor control: the 16-bit Timer1 provides high-resolution PWM with programmable dead-time behavior, and the two 8-bit timers supply additional PWM channels or system ticks. Outputs at 8-bit resolution can run at up to roughly 15.6kHz from a 16MHz clock, pushing beyond audible noise when using phase-correct modes. The 20MHz maximum rating gives headroom for closed-loop control math in firmware, while the ADC samples current shunts or encoder-derived voltages for feedback. brown-out detection ensures safe PWM shutdown during brownout events to protect power stages.
Recommended
Test and Measurement Instruments
Handheld meters, dongle analyzers, and bench accessories use the ATMEGA328P-MU for its precise timing resources and straightforward ADC integration. The 16-bit Timer1 with input capture measures frequency and pulse width with clock-cycle resolution, and the analog comparator provides zero-cross or threshold detection without external components. SPI and USART interfaces stream readings to displays, PCs, or logging modules, while debugWIRE enables single-wire in-circuit debugging during instrument firmware development. The wide 1.8V to 5.5V range supports both battery instruments and USB-powered (5V) designs, and the -40C to +85C rating covers field use.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA328P-MU β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA328PB-MUR | ATMEGA328-MUR | ATMEGA168PA-MU | ATMEGA88PA-MU |
|---|---|---|---|---|---|
| Package | 32-VQFN (5x5 mm) | 32-VQFN (5x5 mm) - same | 32-VQFN (5x5 mm) - same | 32-VQFN (5x5 mm) - same | 32-VQFN (5x5 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 32 KB | 32 KB | 32 KB | 16 KB | 8 KB |
| SRAM | 2 KB | 2 KB | 2 KB | 1 KB | 1 KB |
| EEPROM | 1 KB | 1 KB | 1 KB | 512 B | 512 B |
| Max Clock Speed | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Supply Voltage | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V |
| USART Count | 1 | 2 | 1 | 1 | 1 |
| picoPower Technology | Yes | Yes | No (standard power) | Yes | Yes |
Key Differentiators
- Double the Flash of mid-family parts at identical footprint (vs ATMEGA168PA-MU)
- picoPower efficiency for battery designs (vs ATMEGA328-MUR)
- Deepest ecosystem maturity versus enhanced successor (vs ATMEGA328PB-MUR)
- Twice the EEPROM of lower-memory drop-ins (vs ATMEGA88PA-MU)
Design Notes
Decouple every VCC and AVCC pin with 100nF ceramic capacitors placed within 5mm of the pin, plus one bulk 10uF capacitor near the MCU. AVCC must be connected to VCC even when the ADC is unused, per Microchip datasheet requirements. If ADC accuracy matters, filter AVCC through an LC network (10uH inductor with 100nF/10uF) rather than tying it directly to the noisy digital rail. Ensure the VQFN exposed pad is soldered to a grounded copper pour for both thermal and ground-integrity benefits.
Keep the crystal (pins 7/8, PB6/PB7) within 10mm of the IC with short ground-return traces, and use load capacitors per the crystal specification (typically 12-22pF for common 16MHz crystals). If the ADC is used, route analog signals away from the SPI/USART clock lines and guard the AREF pin with a 100nF capacitor to ground - never place a large capacitor directly on AREF unless the datasheet reference mode allows it. Unused ADC channels can be driven to ground in firmware or tied to ground to prevent floating-input noise.
Fuse misconfiguration is the most common bring-up failure: setting SPIEN incorrectly or disabling RESET (RSTDISBL) can permanently brick the part on the board. Always verify fuses with an ISP programmer before production programming. Additionally, at 5V/20MHz, the internal RC oscillator is not factory-calibrated above 8MHz - an external crystal is required. When migrating from ATMEGA328P to ATMEGA328PB, note that the PB has different default peripheral mappings and its own errata sheet; do not assume register-for-register identity.
Compliance Information
RoHS compliant and lead-free per standard Microchip supply policy for active AVR parts; exact REACH/halogen-free status should be confirmed against the Microchip product page for the specific date code.