Published June 23, 2026. Demand signal from Supplyframe IQ (May 2026 MCU/MPU intelligence). All stock, pricing, and lifecycle figures pulled live from Findchips distributor results on June 23, 2026.
Overview
The ATmega328P is an 8-bit AVR microcontroller from Microchip Technology (formerly Atmel) that is used on the Arduino Uno and Nano, helping make it one of the most searched part numbers tracked in Supplyframe demand data, with the part appearing on the Findchips Most Popular Microcontrollers list.
Join us as we break down the specs of this part, and what buyers and engineers should consider when choosing to source it for their designs.
Next step: Check ATMEGA328P-PU stock, pricing, and lifecycle on Findchips.
What is The ATmega328P
The ATmega328P’s core specifications are 32 KB in system programmable flash, 2 KB SRAM, 1 KB EEPROM, 23 general purpose I/O lines, three timers, a 6 channel or 8 channel 10 bit ADC depending on package, and USART, SPI, and I2C (TWI) serial interfaces. The maximum rated clock is 20 MHz at 4.5 V to 5.5 V, with reduced maximum frequencies at lower voltages.
The base ATmega328P ships in three packages. The ATMEGA328P-PU is a 28-pin PDIP (through hole), the ATMEGA328P-AU is a 32 pin TQFP (surface mount), and the ATMEGA328P-MU is a 32 pin VQFN, also called MLF, at 5 mm by 5 mm (surface mount).
Reel order codes carry an R suffix, for example ATMEGA328P-AUR and ATMEGA328P-MUR. A separate sibling, the ATmega328PB, is a different silicon revision with additional peripherals and is not a pin for pin or fuse for fuse drop in for the ATmega328P. The package and lifecycle differences are detailed in the variant table further down.
Next step: Open the ATMEGA328P-AU package and datasheet details on Findchips.
Common Engineering Questions
“What is the pinout of ATmega328p?”
The pinout depends on the package. The ATMEGA328P-PU is a 28-pin PDIP with two power pins (VCC, GND), AVCC and AREF for the ADC, a reset pin, two crystal pins (XTAL1, XTAL2), and 23 multiplexed I/O lines arranged as PORTB, PORTC, and PORTD.
The 32-pin TQFP (ATMEGA328P-AU) and 32 pin VQFN (ATMEGA328P-MU) add two ADC channels (ADC6, ADC7) and extra power and ground pads, which is why those packages expose a 6 channel ADC in DIP versus an 8 channel ADC in the 32 pin packages. Confirm the exact pin map against the package drawing in the linked datasheet before routing.
Next step: View the ATMEGA328P-PU datasheet and package drawing on Findchips.
“What is the difference between the ATmega328p-pu vs ATmega328p-au?”
They are the same die in different packages. The ATMEGA328P-PU is a 28-pin PDIP for through hole assembly, hand soldering, and socketed prototyping, with a 6 channel ADC. The ATMEGA328P-AU is a 32 pin TQFP for surface mount assembly, with two additional ADC channels (ADC6 and ADC7) and a smaller board footprint.
Firmware is portable between them except for code that references ADC6 or ADC7, which exist only on the 32 pin parts. Compare the two side by side on live stock and price using the links below.
Next step: Compare ATMEGA328P-AU surface mount availability on Findchips.
“What is the difference between ATmega328p and ATmega328pb?”
The ATmega328PB is a later revision with more on chip peripherals: a second USART, a second SPI, a second I2C, two additional 16 bit timers, a unique device signature, and additional I/O. It is not a transparent drop in for the ATmega328P. The device signature bytes differ, some fuse and peripheral behavior differs, and toolchains target it as a separate device, so existing ATmega328P firmware and bootloaders may need changes.
As of June 23, 2026 the ATMEGA328PB-AU carries a lower distributor price than the ATMEGA328P-AU at the same quantities. Verify the peripheral map and signature handling in the linked datasheets before treating one as a substitute for the other.
Next step: Check ATMEGA328PB-AU availability and pricing on Findchips.
“Is the ATmega328p still in production in 2026?”
Yes. Microchip direct listings show a projected end of life date of 2040-11-04 for the ATMEGA328P-PU and ATMEGA328P-AU, and 2040-11-01 for the ATMEGA328P-MU. Rochester Electronics lists the part as Active. No NRND or EOL flag appears across the authorized listings on Findchips as of June 23, 2026. The reader can confirm the current lifecycle status at the link below.
Next step: Confirm ATMEGA328P-PU lifecycle status and projected EOL on Findchips.
“What is a pin compatible alternative to the ATmega328p-au?”
Within the same family, the ATmega168PA and ATmega88PA share the 32 pin TQFP footprint and AVR core but carry less flash (16 KB and 8 KB), and the ATmega328PB occupies the same footprint with more peripherals and a different signature.
Outside the AVR family there is no exact pin for pin equivalent, because the AVR instruction set and peripheral map are specific to this device. Engineers migrating off the part typically move to another AVR with the same footprint or redesign around a different MCU family. Compare footprint compatible AVR options on live distributor stock at the link below.
Next step: View ATMEGA328P-AU and footprint compatible AVR stock on Findchips.
“What is the typical application circuit for ATmega328p?”
A minimal circuit needs decoupling capacitors on VCC and AVCC (typically 100 nF each), a 10 kohm pull up on the reset pin, and optionally a 16 MHz crystal with two load capacitors on XTAL1 and XTAL2 when the internal 8 MHz oscillator is not used.
AVCC connects to VCC through a small inductor or ferrite when ADC accuracy matters, and AREF is decoupled to ground. The Arduino Uno reference schematic is a widely used implementation of this circuit. Confirm decoupling and oscillator loading against the datasheet reference before finalizing.
Next step: Open the ATMEGA328P-PU datasheet and reference schematic on Findchips.
Common Buyer Questions
These are procurement intent questions phrased the way a sourcing buyer would ask them. Figures are live from Findchips on June 23, 2026 and will move, so use the links to recheck.
“Who has ATmega328p-pu in stock right now?”
The 28 pin PDIP shows broad authorized coverage, 13 authorized distributors plus independents. DigiKey holds the deepest authorized position at roughly 43,000 units in tube, with Mouser near 2,455, Onlinecomponents and Master near 2,982, Rochester near 1,340, and Verical near 2,982 in the Americas. Independents add a large buffer, including Chip Stock near 22,000 and Win Source near 12,000. Confirm live quantities at the link below.
Next step: See real time ATMEGA328P-PU stock across distributors on Findchips.
“Cheapest authorized distributor for ATmega328p-au at volume?”
On June 23, 2026 the lowest authorized volume pricing on the ATMEGA328P-AU comes from Microchip direct at roughly $1.93 at the 5,000 unit break and $2.03 at 1,000 units, with Onlinecomponents and Master near $2.10 at similar volumes.
At quantity one, authorized prices run roughly $2.14 to $2.74. Independent listings show lower headline prices in some cases, for example Maritex near $1.77 at 1,000 units. Compare current price breaks at the link below.
Next step: Compare ATMEGA328P-AU authorized price breaks on Findchips.
“What are the current lead times for the ATmega328p?”
Part level lead times on Findchips are short relative to the broader MCU market. Microchip direct shows roughly 2 weeks on the ATMEGA328P-AU tray, 7 weeks on the ATMEGA328P-PU, and 8 weeks on the ATMEGA328P-MU, with Avnet and Arrow near 4 weeks on several lines. A few bulk listings show longer factory lead times as outliers.
For context, Supplyframe IQ reports that MCU and MPU lead times as a category are tightening in Q2 2026, with the Commodity IQ Lead Time Index for that category projected to rise 6.3 percent sequentially to 130.5, so buyers planning large or long horizon builds may want to confirm dates at order time. Check current lead times at the link below.
Next step: Check on hand stock versus lead time for ATMEGA328P-AU on Findchips.
“Is the ATmega328p active, nrnd, or eol?”
Active. Rochester Electronics, an authorized source, lists the status as Active, and Microchip direct shows projected EOL dates around 2040 for the mainstream order codes. No NRND or EOL flag is present across the authorized listings on Findchips as of June 23, 2026. Verify the current status at the link below.
Next step: Verify ATMEGA328P-PU lifecycle status on Findchips.
“Which has more stock: the ATmega328p-au or the ATmega328p-mu?”
As of June 23, 2026 the ATMEGA328P-MU (32 pin VQFN) shows the deeper position, led by Microchip direct in stock near 312,000 units, with reel inventory at DigiKey near 46,000 and Mouser near 43,000 on the ATMEGA328P-MUR.
The ATMEGA328P-AU (32 pin TQFP) also shows deep stock, including a DigiKey reel position near 70,000 on the ATMEGA328P-AUR and Future near 37,000 on the tray part. Both are widely available; package choice usually depends on assembly footprint rather than supply. Compare both at the links below.
Next step: Compare ATMEGA328P-MU stock on Findchips and ATMEGA328P-AU stock on Findchips.
“What are alternate sources for the ATmega328p-pu with shorter lead time?”
For the through hole part, on hand stock from DigiKey near 43,000 units ships from inventory rather than on a factory lead time, and Rochester Electronics holds an authorized buffer near 1,340.
Where a factory order applies, Microchip direct shows roughly 7 weeks on the ATMEGA328P-PU. Buyers needing units sooner than a factory lead time typically split between on hand authorized stock and a scheduled order. Check which sources show on hand stock at the link below.
Next step: Find on hand ATMEGA328P-PU sources on Findchips.
Order Code and Package Reference
These are the most commonly sourced ATmega328P order codes and the closest sibling. The When to Use column describes the use context for each package and is not a recommendation. Confirm live availability at each link.
| Part | Manufacturer | Package | When to Use | Check Availability |
|---|---|---|---|---|
| ATMEGA328P-PU | Microchip Technology | 28 PDIP, through hole, tube | Breadboard prototyping, socketed boards, hand assembly, 6 channel ADC | Check ATMEGA328P-PU availability |
| ATMEGA328P-AU | Microchip Technology | 32 TQFP, surface mount, tray | Surface mount boards, 8 channel ADC, smaller footprint than DIP | Check ATMEGA328P-AU availability |
| ATMEGA328P-AUR | Microchip Technology | 32 TQFP, tape and reel | Volume surface mount production and pick and place | Check ATMEGA328P-AUR availability |
| ATMEGA328P-MU | Microchip Technology | 32 VQFN (MLF) 5×5, surface mount | Space constrained surface mount designs, deepest factory stock | Check ATMEGA328P-MU availability |
| ATMEGA328P-MUR | Microchip Technology | 32 VQFN, tape and reel | Volume QFN production runs | Check ATMEGA328P-MUR availability |
| ATMEGA328PB-AU | Microchip Technology | 32 TQFP, surface mount | Different silicon with more peripherals, not a drop in for ATmega328P | Check ATMEGA328PB-AU availability |
Next step: Compare all ATMEGA328P order codes on one Findchips page.