ATMEGA324P-20AUR - 8-Bit AVR MCU 32KB 20MHz | Microchip
MPN: ATMEGA324P-20AUR β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.93 | $6.93 |
| 10 | $6.24 | $62.40 |
| 100 | $5.47 | $547.00 |
| 500 | $4.98 | $2,490.00 |
| 1,000 | $4.52 | $4,520.00 |
ATMEGA324P-20AUR Overview
An AVR microcontroller is a single-chip embedded controller built on a modified Harvard RISC architecture that executes most instructions in a single clock cycle. Within the product taxonomy it sits at AVR MCU -> 8-bit microcontroller -> microcontroller (MCU) -> embedded processor -> semiconductor. The ATmega324P family is the picoPower generation of the classic ATmega32 line, adding a real-time counter, a JTAG interface, and byte-oriented two-wire serial interface while retaining the 131-instruction AVR core.
Key differentiators include 32 KB of self-programmable Flash with read-while-write support, 1 KB of EEPROM for non-volatile parameter storage, 2 KB of SRAM, and a rich peripheral set: two USARTs, an SPI master/slave, a byte-oriented TWI (I2C) interface, three flexible timer/counters with compare modes and PWM, and an 8-channel 10-bit ADC. The picoPower design keeps active current low and supports six sleep modes, making the device suitable for battery-backed and always-on control applications.
The ATmega324P is fabricated on Microchip's high-endurance Flash process, guaranteeing 10,000 write/erase cycles for Flash and 100,000 cycles for EEPROM. In-system programming is supported through SPI, JTAG, or a bootloader, and the on-chip debug system allows real-time emulation without an external emulator pod.
Typical applications include industrial control panels, building automation nodes, motor control front-ends, battery chargers, handheld instruments, and legacy ATmega32 redesigns where additional USART and timer resources are required. The 44-pin TQFP footprint is shared with the ATmega164P and ATmega644P, allowing memory scaling without PCB changes.
When designing with this device, decouple every VCC pin with a 100 nF ceramic capacitor placed within a few millimeters of the pin, and keep the AREF pin bypassed with 100 nF plus 10 uF when the ADC is used. The 20 MHz rating requires VCC at or above 4.5 V; derate the clock to 10 MHz for 2.7 V operation.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, giving engineers a single reference for selection, replacement, and layout decisions.
Drop-in alternatives for ATMEGA324P-20AUR 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 ATMEGA324P-20AUR (same form factor and footprint) β differing in Package, Flash Memory, Packaging, RoHS Status, EEPROM.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA324PA-AU
β Drop-Inβ In Stock
$2.87 / Unit
View Datasheet βATMEGA324P-20AU
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA324P-20AQR
β Drop-Inβ In Stock
$3.78 / Unit
View Datasheet βATMEGA164P-20AUR
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA644P-20AUR
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA324A-AU
β Drop-Inβ In Stock
$2.09 / Unit
View Datasheet βATMEGA324P-20AUR Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Program Memory Size | 32 KB ISP Flash (16K x 16) |
| EEPROM | 1 KB |
| SRAM | 2 KB |
| Maximum Clock Frequency | 20 MHz |
| Operating Voltage Range | 4.5 V to 5.5 V |
| General Purpose I/O Lines | 32 |
| General Purpose Working Registers | 32 |
| Instruction Set | 131 powerful instructions, most single-clock cycle |
| Package | 44-pin TQFP (10 x 10 mm, 0.80 mm pitch) |
| Operating Temperature Range | -40C to +85C (industrial) |
| ADC | 8-channel 10-bit successive approximation |
| USART Interfaces | 2 |
| Timer/Counters | Three flexible timer/counters with compare modes and PWM |
| Serial Interfaces | SPI master/slave, byte-oriented TWI (I2C) |
| Real Time Counter | Yes, with separate oscillator |
| Flash Endurance | 10,000 write/erase cycles |
| EEPROM Endurance | 100,000 write/erase cycles |
| Programming Interfaces | SPI, JTAG, bootloader (ISP) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
ATMEGA324P-20AUR Pin Configuration
| Pin 1 | PB0 β Port B bit 0 / XCK0 / T0 / PCINT8 |
| Pin 2 | PB1 β Port B bit 1 / T1 / CLKO / PCINT9 |
| Pin 3 | PB2 β Port B bit 2 / INT2 / AIN0 / PCINT10 |
| Pin 4 | PB3 β Port B bit 3 / OC0A / AIN1 / PCINT11 |
| Pin 5 | PB4 β Port B bit 4 / MISO / PCINT12 |
| Pin 6 | PB5 β Port B bit 5 / MOSI / PCINT13 |
| Pin 7 | PB6 β Port B bit 6 / SCK / PCINT14 |
| Pin 8 | PB7 β Port B bit 7 / OC2A / PCINT15 |
| Pin 9 | RESET β Reset input (active low) |
| Pin 10 | VCC β Digital supply voltage |
| Pin 11 | GND β Ground |
| Pin 12 | XTAL2 β Crystal oscillator output / external clock input |
| Pin 13 | XTAL1 β Crystal oscillator input / internal clock |
| Pin 14 | PD0 β Port D bit 0 / RXD0 / PCINT16 |
| Pin 15 | PD1 β Port D bit 1 / TXD0 / PCINT17 |
| Pin 16 | PD2 β Port D bit 2 / RXD1 / INT0 / PCINT18 |
| Pin 17 | PD3 β Port D bit 3 / TXD1 / INT1 / PCINT19 |
| Pin 18 | PD4 β Port D bit 4 / OC1B / PCINT20 |
| Pin 19 | PD5 β Port D bit 5 / OC1A / PCINT21 |
| Pin 20 | PD6 β Port D bit 6 / OC2B / PCINT22 |
| Pin 21 | PD7 β Port D bit 7 / PCINT23 |
| Pin 22 | PC0 β Port C bit 0 / ADC0 / PCINT8 |
| Pin 23 | PC1 β Port C bit 1 / ADC1 / PCINT9 |
| Pin 24 | PC2 β Port C bit 2 / ADC2 / PCINT10 |
| Pin 25 | PC3 β Port C bit 3 / ADC3 / PCINT11 |
| Pin 26 | PC4 β Port C bit 4 / ADC4 / PCINT12 |
| Pin 27 | PC5 β Port C bit 5 / ADC5 / PCINT13 |
| Pin 28 | PC6 β Port C bit 6 / ADC6 / PCINT14 |
| Pin 29 | PC7 β Port C bit 7 / ADC7 / PCINT15 |
| Pin 30 | VCC β Digital supply voltage |
| Pin 31 | GND β Ground |
| Pin 32 | AREF β Analog reference voltage for ADC |
| Pin 33 | PA7 β Port A bit 7 / ADC7 / PCINT7 |
| Pin 34 | PA6 β Port A bit 6 / ADC6 / PCINT6 |
| Pin 35 | PA5 β Port A bit 5 / ADC5 / PCINT5 |
| Pin 36 | PA4 β Port A bit 4 / ADC4 / PCINT4 |
| Pin 37 | PA3 β Port A bit 3 / ADC3 / PCINT3 |
| Pin 38 | PA2 β Port A bit 2 / ADC2 / PCINT2 |
| Pin 39 | PA1 β Port A bit 1 / ADC1 / PCINT1 |
| Pin 40 | PA0 β Port A bit 0 / ADC0 / PCINT0 |
| Pin 41 | PD7 β Port D bit 7 / PCINT23 (alternate location) |
| Pin 42 | PD6 β Port D bit 6 / OC2B / PCINT22 (alternate location) |
| Pin 43 | PD5 β Port D bit 5 / OC1A / PCINT21 (alternate location) |
| Pin 44 | PD4 β Port D bit 4 / OC1B / PCINT20 (alternate location) |
Typical Applications
ATMEGA324P-20AUR is suitable for 6 applications: Industrial Control Panels, Building Automation Nodes, Motor Control Front-Ends, Battery Chargers and Power Management, Handheld Instruments and Data Loggers, Legacy ATmega32 Redesigns.
Industrial Control Panels
The ATMEGA324P-20AUR fits industrial control panels because its 32 KB Flash and 2 KB SRAM can host a PLC-style scan loop, Modbus RTU stack, and HMI driver simultaneously, while the 32 GPIO lines drive relays, opto-isolated inputs, and status LEDs directly. Two USARTs allow one port for RS-485 fieldbus and a second for a local service console. Operating from 4.5 V to 5.5 V matches the 5 V backplane common in factory equipment, and the -40C to +85C industrial rating covers unheated cabinets. The three timer/counters generate PWM for valve or heater control, and the 8-channel 10-bit ADC samples 4-20 mA loops through sense resistors. A practical trade-off is that the 20 MHz clock requires the full 5 V rail, so 3.3 V logic interfaces need level shifters.
Recommended
Building Automation Nodes
Building automation nodes benefit from the ATMEGA324P-20AUR's byte-oriented TWI (I2C) interface, which connects directly to temperature, humidity, and CO2 sensor ICs on a two-wire bus, while the second USART links to a supervisory controller over RS-485. The 1 KB EEPROM stores node addresses, calibration offsets, and schedule tables without external memory, and its 100,000-cycle endurance supports frequent setpoint updates. Six sleep modes let the node idle in power-save between polling intervals, reducing average current in mains-powered and PoE designs alike. The 44-pin TQFP footprint is shared with the ATmega164P and ATmega644P, so a single PCB can be populated with different memory sizes for different node classes. Designers should bypass AREF with 100 nF plus 10 uF when the ADC reads ratiometric sensor dividers.
Recommended
Motor Control Front-Ends
The ATMEGA324P-20AUR suits motor control front-ends because its three flexible timer/counters with compare modes and PWM generate complementary drive signals for H-bridge or three-phase inverter gate drivers, while the 8-channel 10-bit ADC samples phase currents and DC-link voltage. At 20 MHz the AVR core executes most instructions in one clock cycle, giving enough bandwidth for a 10 kHz current-control loop alongside a UART telemetry channel. The real-time counter with its separate oscillator keeps timekeeping alive in power-down mode, useful for scheduled motor starts. Because the device is rated 4.5 V to 5.5 V, it interfaces directly with 5 V gate drivers without level shifting. A key trade-off is that the 10-bit ADC limits current-loop resolution compared with dedicated motor-control MCUs.
Recommended
Battery Chargers and Power Management
Battery chargers and power-management boards use the ATMEGA324P-20AUR to implement CC/CV charge profiles, cell balancing, and fuel-gauge algorithms in firmware. The 10-bit ADC monitors cell voltage, charge current, and temperature, while PWM outputs from the timer/counters drive the buck or boost converter's feedback network. The 1 KB EEPROM logs charge cycles and battery health with 100,000-cycle endurance, and the real-time counter timestamps events during long charge sessions. Six sleep modes allow the controller to enter power-down between measurement bursts, keeping parasitic drain low when the charger is idle. Because the device runs from 4.5 V to 5.5 V, it can be powered directly from a 5 V USB rail. Designers should note that the internal ADC reference drifts with temperature, so an external reference is advisable for accurate fuel gauging.
Recommended
Handheld Instruments and Data Loggers
Handheld instruments and data loggers leverage the ATMEGA324P-20AUR's 32 KB Flash for measurement firmware and 2 KB SRAM for sample buffering, with the 1 KB EEPROM storing calibration coefficients and user profiles. The 8-channel 10-bit ADC digitizes sensor signals, and the byte-oriented TWI interface reads external EEPROM or FRAM for bulk logging when on-chip memory is exhausted. Two USARTs support a PC link and an optional GPS or radio module simultaneously. The picoPower architecture and six sleep modes extend battery life by keeping the MCU in power-save between sampling intervals, waking on the real-time counter. A practical consideration is that the 20 MHz speed grade needs 4.5 V minimum, so battery-powered designs should either use a boost converter or select a lower-speed grade for 3 V operation.
Recommended
Legacy ATmega32 Redesigns
Legacy ATmega32 redesigns migrate to the ATMEGA324P-20AUR because it is the direct architectural successor with the same 131-instruction AVR core, the same 32 KB Flash and 2 KB SRAM, and the same 44-pin TQFP footprint, but adds a second USART, a real-time counter, and a byte-oriented TWI interface. Existing ATmega32 firmware usually recompiles with minimal changes, and the pinout compatibility means the PCB layout can be reused without rework. The 4.5 V to 5.5 V supply range and -40C to +85C rating match the original device's operating envelope. Engineers should verify fuse-bit settings and the bootloader vector table after migration, since the ATmega324P has a larger boot section and different default fuse values than the ATmega32.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA324P-20AUR β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA324PA-AU | ATMEGA324P-20AU | ATMEGA164P-20AUR | ATMEGA644P-20AUR |
|---|---|---|---|---|---|
| Package | 44-pin TQFP (10x10) | 44-pin TQFP (10x10) - same | 44-pin TQFP (10x10) - same | 44-pin TQFP (10x10) - same | 44-pin TQFP (10x10) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 32 KB | 32 KB | 32 KB | 16 KB | 64 KB |
| SRAM | 2 KB | 2 KB | 2 KB | 1 KB | 4 KB |
| EEPROM | 1 KB | 1 KB | 1 KB | 512 B | 2 KB |
| Maximum Clock Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Operating Voltage | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V |
| GPIO Lines | 32 | 32 | 32 | 32 | 32 |
| Packaging | Tape & Reel | Tray | Tray | Tape & Reel | Tape & Reel |
| Temperature Range | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
Key Differentiators
- Dual USART plus TWI and SPI in a 44-pin footprint (vs ATMEGA164P-20AUR)
- Newer PA revision available for long-life designs (vs ATMEGA324PA-AU)
- Tape-and-reel delivery for automated assembly (vs ATMEGA324P-20AU)
- Extended temperature option in the same footprint (vs ATMEGA324P-20AQR)
Design Notes
Decouple every VCC pin (pins 10 and 30) with a 100 nF ceramic capacitor placed within a few millimeters of the pin, and add a 10 uF bulk capacitor near the regulator output. When the ADC is used, bypass AREF (pin 32) with 100 nF in parallel with 10 uF to keep the reference quiet. Estimated: at 20 MHz and 5 V the core draws on the order of 10-15 mA, so a 100 mA LDO provides ample margin for the MCU plus I/O loading.
Keep the crystal and its two load capacitors as close as possible to XTAL1 (pin 13) and XTAL2 (pin 12), with a solid ground plane beneath and no traces routed under the crystal. Guard the analog supply and AREF traces away from the SPI and USART lines. Route the 44-pin TQFP escape with 0.25 mm traces and 0.5 mm vias to preserve the 0.80 mm pad pitch clearance.
The JTAG interface shares pins with Port C (PC2-PC5), so designs that use those pins as GPIO must disable JTAG via the fuse bits or reserve them for programming. Also verify the clock fuse selection: the ATmega324P ships with the internal 8 MHz oscillator divided by 8, so an external 20 MHz crystal requires correct CKSEL and CKDIV8 fuse programming before the device will run at full speed.
The 44-pin TQFP has no exposed thermal pad, so heat is conducted through the leads into the PCB copper. Estimated: at 5 V and 15 mA the device dissipates roughly 75 mW, giving a negligible junction rise in still air; no thermal relief is required. If the MCU sinks significant I/O current, keep total port current within the datasheet absolute maximum and provide copper area on the ground pins.
Compliance Information
RoHS compliance is stated on the Microchip ATmega324P product page. REACH, halogen-free, lead-free finish, and conflict-minerals status were not present in the retrieved web data and are therefore marked unknown rather than assumed. The device is not AEC-Q100 qualified; the industrial temperature grade is -40C to +85C.
