ATmega328P-AU and ATmega328P-PU are two ordering variants of the ATmega328P 8-bit AVR microcontroller. The core MCU architecture and major memory resources are broadly the same, but the package and mounting method are different. This makes the comparison particularly important when selecting an ATmega328P device for a new PCB or modifying an existing design.
For engineers searching for ATmega328P-AU vs ATmega328P-PU, the main difference is not the MCU family itself. The key distinction is the package: ATmega328P-AU is supplied in a 32-lead TQFP package, while ATmega328P-PU uses a 28-lead PDIP package.
Both devices belong to the ATmega328P family and use the 8-bit AVR architecture. The ATmega328P provides 32 KB of programmable Flash, 2 KB of SRAM, and 1 KB of EEPROM. It also provides 23 programmable I/O lines, timers, PWM, ADC, USART, SPI, and a two-wire serial interface.
The important difference between these two part numbers is the package implementation.
ATmega328P-AU uses a 32-pin TQFP package for surface-mount PCB assembly.
ATmega328P-PU uses a 28-pin PDIP package for through-hole mounting.
This difference can have a major effect on PCB layout, assembly method, board size, and available I/O connections.
The ATmega328P-AU is associated with the TQFP package and is intended for surface-mount applications.
A TQFP package can provide a more compact solution than a through-hole DIP package, making it suitable for products where PCB space is limited.
The surface-mount package is also well suited to automated PCB assembly processes such as SMT production.
When designing around ATmega328P-AU, engineers should check the exact PCB footprint, pad dimensions, package drawing, pin numbering, thermal considerations, and assembly requirements.
ATmega328P-PU uses a 28-pin PDIP package.
The DIP format is larger than the TQFP package and is designed for through-hole mounting. It can be convenient for prototyping, educational projects, development boards, and designs where manual replacement or socket mounting is useful.
Because the package uses through-hole leads, the PCB footprint and board area are substantially different from the ATmega328P-AU implementation.
Therefore, ATmega328P-PU should not be considered a direct physical replacement for ATmega328P-AU without PCB modification.
The memory architecture is one of the similarities between ATmega328P variants.
The ATmega328P family provides:
32 KB Flash program memory
2 KB SRAM
1 KB EEPROM
The Flash memory supports in-system programming and includes read-while-write capabilities. The device also provides a boot code section with programmable lock bits for applications that use a bootloader.
For firmware migration between ATmega328P-AU and ATmega328P-PU, the common MCU family means that the memory architecture is an important point of continuity.
However, engineers should still verify the exact ordering code and applicable datasheet before production use.
The ATmega328P is an 8-bit AVR RISC-based microcontroller.
The architecture provides 32 general-purpose working registers and supports instructions that can execute in a single clock cycle. The datasheet specifies throughput approaching one MIPS per MHz and operation up to 16 MHz under the applicable conditions.
Some current distributor listings describe particular ATmega328P ordering variants with a maximum frequency of 20 MHz, so engineers should verify the exact device revision and operating conditions against the applicable Microchip documentation rather than applying one frequency specification to every ordering code.
The ATmega328P provides 23 programmable I/O lines at the device level, although the number of accessible I/O pins can vary with the package. Microchip lists interfaces and peripherals including USART, SPI, a two-wire serial interface, timers, PWM, ADC, analog comparator, watchdog timer, and interrupt functions.
This package-dependent I/O availability is an important consideration when comparing ATmega328P-AU and ATmega328P-PU.
The TQFP version provides access to more of the device's I/O resources than the 28-pin PDIP version. The datasheet specifically identifies the 8-channel ADC availability for TQFP and QFN/MLF packages.
The ATmega328P includes analog and timer resources that make it useful for embedded control applications.
The device provides a 10-bit ADC and PWM channels. The TQFP and QFN/MLF versions provide eight ADC channels, while package selection affects the available pin functions.
These peripherals can be used for sensor interfaces, analog measurement, motor or actuator control, LED control, and other embedded applications.
When moving between package variants, engineers should therefore review the actual pinout rather than assuming that every peripheral signal is available on every package.
PCB design is one of the biggest differences between these two part numbers.
ATmega328P-AU is designed for surface mounting and generally requires a compact SMT footprint.
ATmega328P-PU uses through-hole leads and requires larger PCB holes and a larger component footprint.
This means an existing board designed for ATmega328P-AU cannot normally accept ATmega328P-PU without a PCB redesign or adapter.
Likewise, a board designed for the PDIP version cannot simply accept the TQFP version without changing the footprint and assembly method.
For prototype development, ATmega328P-PU can be convenient because its DIP package is easy to handle and can be installed in a socket.
This can be useful during firmware development, debugging, educational projects, and low-volume prototypes.
ATmega328P-AU is more suitable when the target product is designed around SMT manufacturing and compact PCB construction.
The choice therefore depends not only on MCU performance but also on the development and production process.
The ATmega328P platform can be used in a broad range of embedded applications.
Typical applications include:
Embedded control systems
Sensor interfaces
Consumer electronics
Automation equipment
Measurement equipment
Educational electronics
Development boards
Small control systems
The combination of Flash, SRAM, EEPROM, timers, ADC, PWM, and serial communication interfaces allows the MCU to support many applications without requiring a large number of external controllers.
From an MCU family perspective, ATmega328P-AU and ATmega328P-PU share the same ATmega328P platform. However, they should not be treated as physically interchangeable components.
The main issue is package compatibility.
ATmega328P-AU uses a 32-lead TQFP package, while ATmega328P-PU uses a 28-lead PDIP package. Their PCB footprints, mounting methods, and accessible pin functions therefore differ.
For firmware, engineers can generally work within the same ATmega328P family architecture, but the hardware design must account for the package-specific pinout and peripheral availability.
The comparison can be summarized around several practical points.
ATmega328P-AU is a surface-mount TQFP variant with 32 leads.
ATmega328P-PU is a through-hole PDIP variant with 28 leads.
Both belong to the ATmega328P family and share the core AVR architecture and major memory resources.
The major engineering difference is therefore the physical package and the resulting PCB implementation.
For a new design, ATmega328P-AU may be preferable when compact SMT assembly is required. ATmega328P-PU can be useful when through-hole assembly, socketing, or easy manual prototyping is preferred.
The correct part number should be selected according to the complete product requirements.
Before selecting an ATmega328P variant, engineers should check:
Package type
Pin count
Pin assignment
Available I/O
ADC channels
PCB footprint
Assembly process
Operating voltage
Clock requirements
Memory requirements
Programming interface
Production environment
These checks are especially important when changing an existing PCB from one ATmega328P package to another.
ATmega328P-AU and ATmega328P-PU are not different MCU families. They are package-specific ordering variants of the ATmega328P platform.
For engineers comparing these two part numbers, the most important distinction is the package: ATmega328P-AU uses TQFP surface mounting, while ATmega328P-PU uses PDIP through-hole mounting.
The MCU architecture and major memory resources remain centered on the ATmega328P platform, but the package affects PCB layout, I/O availability, assembly, and product size.
For an existing design, the complete ordering code and package-specific documentation should be checked before making a component change.
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