ATMEGA328PB-MU - 8-Bit AVR MCU 20MHz 32KB Flash | Microchip
MPN: ATMEGA328PB-MU ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.77 | $1.77 |
| 10 | $1.62 | $16.20 |
| 100 | $1.45 | $145.00 |
| 500 | $1.32 | $660.00 |
| 1,000 | $1.19 | $1,190.00 |
ATMEGA328PB-MU Overview
An 8-bit AVR microcontroller is a self-contained computing IC that integrates a RISC CPU core, program Flash, SRAM, EEPROM, and peripherals such as timers, USART, SPI, and I2C on a single die. Within the power-management hierarchy of embedded systems, it functions as the system controller, executing application firmware while managing sensors, actuators, and communication links.
Key features include two 8-bit timer/counters with PWM, one 16-bit timer/counter, and enhanced peripheral sets relative to the ATmega328P: two independent I2C interfaces, two SPI interfaces, additional GPIO on PORTE, and a 10-bit ADC with 7 multiplexed channels. The picoPower technology supports multiple sleep modes for battery-operated designs, and the device executes powerful instructions in a single clock cycle.
The AVR enhanced RISC architecture pairs 32 general-purpose working registers directly with the ALU, allowing most instructions to complete in one cycle and delivering deterministic, interrupt-friendly real-time behavior. Flash read-while-write capability enables in-system self-programming via a boot loader, and ISP plus debugWIRING support simplifies field updates and development.
Typical applications include Arduino-compatible boards and maker platforms, industrial sensor nodes and HMI controllers, and consumer appliances requiring low-cost, low-power control with robust community tooling.
When designing with this device, verify that your firmware and fuse settings are written for the 328PB signature, because the added Port E pins (19 and 22 in the QFN) change connectivity relative to the ATmega328P footprint.
This page synthesizes distributor pricing, verified drop-in alternatives, and practical design notes not consolidated in the manufacturer datasheet.
Drop-in alternatives for ATMEGA328PB-MU — 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 ATMEGA328PB-MU (same form factor and footprint) — differing in Package, Timers, Communication Interfaces, ADC Channels, RoHS Status.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA328P-MU
✅ Drop-In✓ In Stock
$1.28 / Unit
View Datasheet →ATMEGA328-MUR
✅ Drop-In✓ In Stock
$1.84 / Unit
View Datasheet →ATMEGA168PB-MU
✅ Drop-In✓ In Stock
$1.31 / Unit
View Datasheet →ATMEGA168PA-MU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.72 / Unit
View Datasheet →ATMEGA328PB-MU Maximum Ratings & Electrical Characteristics
| Core Architecture | AVR 8-bit RISC |
| Core Size | 8-Bit |
| Maximum Clock Frequency | 20 MHz |
| Program Memory Size | 32 KB (16K x 16) FLASH |
| SRAM Size | 2 KB |
| EEPROM Size | 1 KB |
| Performance | Approx. 1 MIPS per MHz |
| I/O Count | 27 GPIO (incl. PORTE [3:0] on QFN) |
| Package | 32-VFQFN (5x5 mm) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C (Industrial) |
| ADC Resolution | 10-bit |
| Timers | 2 x 8-bit, 1 x 16-bit |
| Communication Interfaces | USART, 2 x SPI, 2 x I2C (TWI) |
| Low Power Technology | picoPower, multiple sleep modes |
| Programming | ISP, debugWIRING, self-programming boot loader |
| Safety Qualification | Functional Safety (FuSa) supported per DigiKey |
| RoHS Status | Compliant (GREEN package per FindIC) |
ATMEGA328PB-MU Pin Configuration
| Pin 1 | PD3 — Port D bit 3 / PCINT19 |
| Pin 2 | PD4 — Port D bit 4 / PCINT20 / XCK |
| Pin 3 | GND — Ground |
| Pin 4 | PD5 — Port D bit 5 / PCINT21 / OC0B / T1 |
| Pin 6 | VCC — Digital supply voltage |
| Pin 7 | PB6 — Port B bit 6 / XTAL1 (clock input) |
| Pin 8 | PB7 — Port B bit 7 / XTAL2 (clock output) |
| Pin 9 | PD7 — Port D bit 7 / PCINT23 / AIN1 |
| Pin 10 | PB0 — Port B bit 0 / PCINT0 / SS |
| Pin 11 | PB1 — Port B bit 1 / PCINT1 / OC1A |
| Pin 12 | PB2 — Port B bit 2 / PCINT2 / OC1B / SS |
| Pin 13 | PB3 — Port B bit 3 / MOSI / OC2A |
| Pin 14 | PB4 — Port B bit 4 / MISO / PCINT4 |
| Pin 15 | PB5 — Port B bit 5 / SCK / PCINT5 |
| Pin 16 | AVCC — ADC supply voltage |
| Pin 19 | PE2 — Port E bit 2 / ADC6 (extra GPIO on 328PB QFN) |
| Pin 20 | AREF — Analog reference for ADC |
| Pin 22 | PE3 — Port E bit 3 / ADC7 (extra GPIO on 328PB QFN) |
| Pin 23 | PC0 — Port C bit 0 / ADC0 |
| Pin 24 | PC1 — Port C bit 1 / ADC1 |
| Pin 25 | PC2 — Port C bit 2 / ADC2 |
| Pin 26 | PC3 — Port C bit 3 / ADC3 |
| Pin 27 | PC4 — Port C bit 4 / ADC4 / SDA |
| Pin 28 | PC5 — Port C bit 5 / ADC5 / SCL |
| Pin 29 | PC6 — Port C bit 6 / RESET (active low) |
| Pin 30 | PD0 — Port D bit 0 / RXD (USART receive) |
| Pin 31 | PD1 — Port D bit 1 / TXD (USART transmit) |
| Pin 32 | PD2 — Port D bit 2 / INT0 |
Typical Applications
ATMEGA328PB-MU is suitable for 6 applications: Arduino-Compatible Development Boards, Industrial Sensor Nodes, Consumer Appliance Control, Battery-Powered Portable Instruments, Embedded IoT Edge Controllers, Motor Control and Actuation.
Arduino-Compatible Development Boards
The ATMEGA328PB-MU is the natural successor for Arduino Uno-class designs, retaining the AVR instruction set, 32 KB Flash, and 20 MHz headroom while adding the dual I2C and dual SPI buses that the original 328P lacked. Board designers can host two independent sensor buses or add a second SPI display while preserving full Arduino IDE compatibility via the 328PB core package. The picoPower sleep modes also let portable shield projects match or beat 328P idle current. Because the QFN-32 footprint matches the 328P MLF with only pins 19/22 needing review, existing carrier boards migrate with minimal respin, and bootloader/fuse settings remain directly reusable from prior 328P firmware builds.
Recommended
Industrial Sensor Nodes
In factory and process monitoring, the ATMEGA328PB-MU's 10-bit ADC with up to 7 external channels (including PE2/PE3 as ADC6/ADC7) digitizes multiple analog sensors from a single MCU, while the industrial -40C to +85C rating covers unconditioned enclosures. Dual I2C interfaces let one node talk to a local sensor cluster and a separate system-management bus without bus contention, and the 16-bit timer supports precise pulse capture for flow or encoder signals. picoPower power-down mode extends battery and energy-harvesting node lifetimes, and the Functional Safety (FuSa) designation per DigiKey listing supports documented deployment in monitored industrial equipment.
Recommended
Consumer Appliance Control
White-goods and small-appliance control boards benefit from the ATMEGA328PB-MU's cost profile (about $1.77 at qty 1 as of 2026-09-17) and its deterministic 1 MIPS per MHz execution, which simplifies certification of fixed-loop control algorithms for heaters, motors, and user interfaces. The three timers (two 8-bit, one 16-bit) drive multiple PWM channels for fan and brightness control while maintaining a system tick. ISP self-programming via a resident boot loader enables field firmware updates over existing wiring, and the GREEN/RoHS-compliant QFN package meets consumer environmental requirements without leaded assembly processes.
Recommended
Battery-Powered Portable Instruments
Handheld meters and loggers exploit picoPower sleep modes to achieve multi-year battery life: in power-down the MCU halts while retaining SRAM, waking on pin-change or watchdog interrupts. At reduced clock frequencies the 1 MIPS per MHz core keeps processing budget adequate at microamp-scale average draw, and the on-chip 10-bit ADC with internal reference digitizes battery voltage and sensor inputs without external conversion ICs. Dual SPI interfaces let one ATMEGA328PB-MU manage both a flash memory data logger and an RF or display module, removing a multiplexer that a single-SPI 328P design would require, saving board area and BOM cost in compact enclosures.
Recommended
Embedded IoT Edge Controllers
For sub-GHz RF modules and simple IoT endpoints, the ATMEGA328PB-MU pairs a UART to an external radio while its dual I2C buses separate a secure-element or sensor path from the main bus, improving isolation and fault containment. The 32 KB Flash accommodates a TCP/UDP-style protocol stack plus OTA boot loader within a single chip, and debugWIRING plus ISP support streamlines provisioning. The 5x5 mm VFQFN keeps endpoint PCBs small, and the FuSa designation listed by DigiKey adds documentation leverage for functional-safety-assessed IoT deployments. Fuse-locked boot loader regions protect field-deployed firmware against casual extraction.
Recommended
Motor Control and Actuation
Small DC and stepper motor systems use the ATMEGA328PB-MU's two 8-bit timers and one 16-bit timer to generate multi-channel PWM with hardware phase accuracy, while external H-bridge drivers handle the power stage. The 16-bit timer input-capture measures encoder or back-EMF feedback with system-clock resolution, enabling closed-loop speed control on an 8-bit budget. The 20 MHz maximum clock provides 20 MIPS for PID loops executing in firmware, comfortably servoing most small actuators. Dual SPI allows simultaneous control of a driver chip and a diagnostics ADC, and the industrial temperature rating suits actuator housings near heat sources such as motors and drivers.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA328PB-MU — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA328P-MU | ATMEGA328-MUR | ATMEGA168PB-MU | ATMEGA168PA-MU |
|---|---|---|---|---|---|
| Package | 32-VFQFN (5x5 mm) | 32-VFQFN (5x5 mm) - same | 32-VFQFN (5x5 mm) - same | 32-VFQFN (5x5 mm) - same | 32-VFQFN (5x5 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Flash | 32 KB | 32 KB | 32 KB | 16 KB | 16 KB |
| SRAM | 2 KB | 2 KB | 2 KB | 1 KB | 1 KB |
| Max Clock | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| I2C Interfaces | 2 | 1 | 1 | 2 | 1 |
| SPI Interfaces | 2 | 1 | 1 | 2 | 1 |
| Extra PORTE GPIO (pins 19/22) | Yes (PE2/PE3) | No (legacy ADC6/ADC7) | No | Yes (PE2/PE3) | No |
| Operating Temperature | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
Key Differentiators
- Dual I2C and dual SPI buses on one chip (vs ATMEGA328P-MU)
- Two extra GPIO/ADC channels via PORTE (vs ATMEGA328P-MU)
- Same core, half the memory option for cost-down (vs ATMEGA168PB-MU)
- Trade-off: legacy pinout compatibility (vs ATMEGA328P-MU)
Design Notes
Do not assume the ATMEGA328PB-MU is a blind drop-in for the ATMEGA328P-MU. Per Microchip documentation and community analysis, PE2 and PE3 occupy QFN pins 19 and 22, multiplexed with ADC6/ADC7, and pins 3 (GND) and 6 (VCC) differ in connectivity versus the legacy 328P MLF. Audit your schematic for any connection on pins 19 and 22 before respinning, and ensure the device signature and fuses are set for the 328PB in your programmer project files.
Decouple VCC and AVCC separately with 100 nF ceramic capacitors placed within 2 mm of pins 6 and 16 respectively, each with a low-impedance via to the ground plane. AVCC must be connected even if the ADC is unused, per the Microchip datasheet. When using PE2/PE3 as ADC6/ADC7 channels, keep analog routing away from the XTAL1/XTAL2 traces on pins 7/8 to preserve ADC noise performance at the 10-bit level.
The 32-VFQFN (5x5 mm) has a 0.5 mm pitch and center exposed pad; create a solder-mask-defined land pattern per IPC guidance and print approximately 6-8 mils of solder paste on the center pad via an array of small apertures (50-60 percent coverage) to prevent float. X-ray or AOI inspection is recommended for volume assembly. The center pad should be tied to GND with a via array to improve thermal dissipation and ground integrity.
Compliance Information
FindIC lists the ATMEGA328PB-MU as GREEN packaging, indicating RoHS-compliant lead-free production. Formal REACH/halogen-free/conflict-minerals statements should be pulled from the Microchip compliance portal for the specific date code.
