ATMEGA324P-20AQR - 8-bit AVR MCU, 32KB Flash, 20MHz | Microchip
MPN: ATMEGA324P-20AQR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.9 | $5.90 |
| 10 | $5.31 | $53.10 |
| 100 | $4.72 | $472.00 |
| 500 | $4.25 | $2,125.00 |
| 1,000 | $3.78 | $3,780.00 |
ATMEGA324P-20AQR Overview
An 8-bit AVR microcontroller is a single-chip computing device that integrates a Harvard-architecture RISC processor core, program Flash memory, data SRAM, nonvolatile EEPROM, and a rich set of peripherals (timers, USARTs, SPI, ADC) on one die. Within the power-management hierarchy, microcontrollers such as the ATmega324P sit at the top of embedded control systems, replacing discrete MCU-plus-logic combinations in cost- and power-sensitive designs.
Key features of this device include 131 powerful instructions with most executing in a single clock cycle, 32 general-purpose working registers, and read-while-write Flash that allows firmware self-programming. The picoPower technology provides aggressive sleep modes - power-down, power-save, and standby - for battery applications. Two USARTs, one SPI, one two-wire (I2C) interface, an 8-channel 10-bit ADC, and a JTAG boundary-scan/debug port round out the peripheral set.
Architecturally, the advanced RISC core is fully static, allowing clock frequencies down to DC without state loss. Hardware multipliers and single-cycle ALU operations let the ATMEGA324P-20AQR sustain up to 16-20 MIPS, while the pipelined fetch achieves near one-MIPS-per-MHz efficiency. In-system programmability via SPI (ICSP) and JTAG on-chip debugging simplify development and field updates.
Typical applications include industrial automation nodes and sensor hubs (extended temperature rating supports harsh environments), consumer appliances and HVAC controllers that leverage the 10-bit ADC, and battery-powered meters where picoPower sleep currents extend battery life for years.
Design consideration: the 44-pin TQFP requires careful decoupling - place 100 nF ceramic capacitors at both VCC pins and AVCC close to the die, and route the reset trace short with an external 10 kOhm pull-up for reliable ICSP programming.
This page synthesizes verified distributor data, drop-in alternative MPNs, pinout detail, and practical design notes not consolidated in the manufacturer datasheet.
Drop-in alternatives for ATMEGA324P-20AQR — 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-20AQR (same form factor and footprint) — differing in Package, Program Memory Size, Serial Interfaces, RoHS Status, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA324PA-AUR
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.98 / Unit
View Datasheet →ATMEGA324P-20AUR
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$4.52 / Unit
View Datasheet →ATMEGA324A-AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.09 / Unit
View Datasheet →ATMEGA644P-20AUR
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
ATMEGA164P-20AUR
✅ Drop-In📋 Reference alternative (not in catalog)
ATMEGA32-16AUR
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$3.41 / Unit
View Datasheet →ATMEGA324P-20AQR Maximum Ratings & Electrical Characteristics
| Core Processor | AVR |
| Core Size | 8-bit |
| Speed | 20 MHz |
| Flash Memory | 32 KB (16K x 16) |
| EEPROM Size | 1 KB |
| RAM Size | 2 KB |
| Supply Voltage (Vcc/Vdd) | 2.7 V to 5.5 V |
| GPIO Count | 32 |
| Number of USARTs | 2 |
| Peripherals | SPI, TWI (I2C), JTAG, WDT, Brown-out Detect/Reset, PWM |
| ADC Resolution | 10-bit, 8 channels |
| MIPS Throughput | Up to 16-20 MIPS (1 MIPS/MHz) |
| Package | 44-TQFP (10x10 mm) |
| Mounting Type | Surface Mount |
| Operating Temperature | Extended (A-variant), per Microchip extended range |
| Oscillator Type | Internal |
| Program Memory Type | ISP FLASH, read-while-write |
| RoHS Status | Compliant (GREEN package) |
| Packaging | Tape & Reel (T&R) |
ATMEGA324P-20AQR Pin Configuration
| Pin 1 | PA0 (ADC0) — Port A bit 0 / ADC channel 0 |
| Pin 2 | PA1 (ADC1) — Port A bit 1 / ADC channel 1 |
| Pin 3 | PA2 (ADC2) — Port A bit 2 / ADC channel 2 |
| Pin 4 | PA3 (ADC3) — Port A bit 3 / ADC channel 3 |
| Pin 5 | PA4 (ADC4) — Port A bit 4 / ADC channel 4 |
| Pin 6 | PA5 (ADC5) — Port A bit 5 / ADC channel 5 |
| Pin 7 | PA6 (ADC6) — Port A bit 6 / ADC channel 6 |
| Pin 8 | PA7 (ADC7) — Port A bit 7 / ADC channel 7 |
| Pin 9 | PB0 (SS) — Port B bit 0 / SPI slave select |
| Pin 10 | PB1 (T1) — Port B bit 1 / Timer1 external clock |
| Pin 11 | PB2 (INT2/AIN0) — Port B bit 2 / external interrupt 2 / analog comparator input |
| Pin 12 | PB3 (AIN1/INT0/MOSI) — Port B bit 3 / comparator input / interrupt 0 / SPI MOSI |
| Pin 13 | PB4 (OC0A/MISO) — Port B bit 4 / Timer0 output compare A / SPI MISO |
| Pin 14 | PB5 (OC1A/SCK) — Port B bit 5 / Timer1 output compare A / SPI clock |
| Pin 15 | PB6 (OC1B/XTAL1) — Port B bit 6 / Timer1 output compare B / crystal input 1 |
| Pin 16 | PB7 (OC2A/XTAL2) — Port B bit 7 / Timer2 output compare A / crystal output 2 |
| Pin 17 | VCC — Digital supply voltage |
| Pin 18 | GND — Ground |
| Pin 19 | PC0 (SCL) — Port C bit 0 / TWI clock |
| Pin 20 | PC1 (SDA) — Port C bit 1 / TWI data |
| Pin 21 | PC2 (TCK) — Port C bit 2 / JTAG test clock |
| Pin 22 | PC3 (TMS) — Port C bit 3 / JTAG test mode select |
| Pin 23 | PC4 (TDO) — Port C bit 4 / JTAG test data out |
| Pin 24 | PC5 (TDI) — Port C bit 5 / JTAG test data in |
| Pin 25 | PC6 (TOSC1) — Port C bit 6 / Timer oscillator input 1 |
| Pin 26 | PC7 (TOSC2) — Port C bit 7 / Timer oscillator output 2 |
| Pin 27 | PD0 (RXD0) — Port D bit 0 / USART0 receive |
| Pin 28 | PD1 (TXD0) — Port D bit 1 / USART0 transmit |
| Pin 29 | PD2 (RXD1/INT0) — Port D bit 2 / USART1 receive / external interrupt 0 |
| Pin 30 | PD3 (TXD1/INT1) — Port D bit 3 / USART1 transmit / external interrupt 1 |
| Pin 31 | PD4 (OC1B) — Port D bit 4 / Timer1 output compare B |
| Pin 32 | PD5 (XCK1) — Port D bit 5 / USART1 external clock |
| Pin 33 | PD6 (XCK0) — Port D bit 6 / USART0 external clock |
| Pin 34 | PD7 (OC2A) — Port D bit 7 / Timer2 output compare A |
| Pin 35 | AVCC — ADC supply voltage |
| Pin 36 | AREF — ADC reference voltage |
| Pin 37 | GND — Ground |
| Pin 38 | PE0 (XCK0/AIN0) — Port E bit 0 / USART0 clock / comparator input |
| Pin 39 | PE1 (OC0B/AIN1) — Port E bit 1 / Timer0 output compare B / comparator input |
| Pin 40 | PE2 (T0) — Port E bit 2 / Timer0 external clock |
| Pin 41 | PE3 (T1) — Port E bit 3 / Timer1 external clock |
| Pin 42 | VCC — Digital supply voltage |
| Pin 43 | GND — Ground |
| Pin 44 | RESET — Reset input (active low) |
Typical Applications
ATMEGA324P-20AQR is suitable for 6 applications: Industrial Automation Nodes, Battery-Powered Metering, HVAC and Appliance Control, Sensor Hubs and Data Loggers, Embedded Networking and Gateways, Motor Control and PWM Systems.
Industrial Automation Nodes
The ATMEGA324P-20AQR fits industrial automation nodes such as PLC I/O satellites, motor-control panels, and sensor concentrators because its extended-temperature AQR grade sustains operation in hot cabinets, and its 20 MHz core delivers up to 16-20 MIPS for deterministic control loops. The two USARTs let one channel run RS-485 Modbus RTU while the second services debugging or an HMI, and the 8-channel 10-bit ADC digitizes potentiometers, current-shunt signals, and thermistors directly. Placed on a 5V industrial rail with brown-out detection enabled and a watchdog running, the MCU tolerates noisy power environments. The JTAG port supports boundary-scan production test and in-circuit debugging, reducing field-service iterations.
Recommended
Battery-Powered Metering
In battery-powered electricity, water, and heat meters, the ATMEGA324P-20AQR's picoPower sleep architecture keeps average drain near the sleep-mode floor: the MCU wakes on RTC or sensor interrupts, samples the 10-bit ADC or pulses a reed input, and returns to a deep sleep mode. The 32 KB Flash stores calibration tables, multi-tariff firmware, and logging algorithms, while 1 KB EEPROM retains accumulated registers and calibration data through battery swaps. Running from 3V lithium cells within the 2.7V-5.5V supply range, the device avoids a boost converter in many designs. For designs pushing multi-year life, the pin-compatible ATMEGA324PA revision lowers active and sleep currents further without PCB change.
Recommended
HVAC and Appliance Control
The ATMEGA324P-20AQR is a strong fit for HVAC controllers, boilers, and white-goods appliance boards. Its 32 general-purpose I/O lines drive relays, triac gates, stepper valves, and seven-segment displays without port expanders, while the 8-channel 10-bit ADC reads NTC thermistors, pressure sensors, and user potentiometers at 10-bit resolution adequate for ±1C temperature control. The 20 MHz core executes PID loops and communications with headroom, and the hardware PWM channels generate zero-cross-synchronized triac or fan-control waveforms. Extended-temperature qualification handles compressor-bay ambient conditions, and the internal oscillator option removes the crystal from cost-sensitive appliance BOMs where timing accuracy requirements are modest.
Recommended
Sensor Hubs and Data Loggers
As a sensor-hub MCU, the ATMEGA324P-20AQR aggregates SPI and I2C sensors while streaming data over one of its two USARTs to a radio or host. The hardware TWI master drives multiple I2C devices on one bus, the SPI port services high-rate ADCs or SD-card media at several MHz, and 2 KB SRAM buffers sample bursts. With 32 KB of read-while-write Flash, firmware stores logged records in unused Flash pages or the 1 KB EEPROM, surviving power loss without external NVRAM. The picoPower modes suit duty-cycled loggers that sleep between acquisition windows, and the JTAG debug interface shortens bring-up of multi-sensor timing-critical code.
Recommended
Embedded Networking and Gateways
With two independent hardware USARTs, the ATMEGA324P-20AQR bridges serial protocols in embedded gateways - for example translating RS-485 Modbus on one port to RS-232 or a wireless module's AT-command interface on the other. The 20 MHz clock sustains sustained 115.2 kbaud full-duplex traffic with interrupt-driven buffering in the 2 KB SRAM, while the SPI or TWI port manages MAC/PHY companion chips for Ethernet add-ons. Hardware flow-control-capable USARTs and a watchdog timer give the robustness expected of always-on network devices. The 44-TQFP footprint also leaves routed GPIO for status LEDs, configuration DIP switches, and reset supervision of attached modules.
Recommended
Motor Control and PWM Systems
The ATMEGA324P-20AQR suits DC and stepper motor control boards: hardware PWM outputs from its timers generate speed-control waveforms, the 10-bit ADC reads back current via shunt amplifiers and position via potentiometers, and external interrupts on INT0/INT1 capture quadrature encoder edges. At 20 MHz the core closes PID loops in the tens-of-microseconds range, fast enough for most hobby-scale and light-industrial drives. Brown-out reset and a watchdog protect against latch-up during stall currents, and the extended-temperature grade suits motor-adjacent mounting where ambient temperatures climb. Firmware can implement fault curves and soft-start sequences entirely on-chip with no external supervisor logic.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA324P-20AQR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA324PA-AUR | ATMEGA324A-AU | ATMEGA644P-20AUR | ATMEGA164P-20AUR | ATMEGA32-16AUR |
|---|---|---|---|---|---|---|
| Package | 44-TQFP (10x10 mm) | 44-TQFP (10x10 mm) - same | 44-TQFP (10x10 mm) - same | 44-TQFP (10x10 mm) - same | 44-TQFP (10x10 mm) - same | 44-TQFP (10x10 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 32 KB | 32 KB | 32 KB | 64 KB | 16 KB | 32 KB |
| SRAM | 2 KB | 2 KB | 2 KB | 4 KB | 1 KB | 2 KB |
| Max Speed | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 16 MHz |
| Supply Voltage | 2.7 V to 5.5 V | 1.8 V to 5.5 V (speed-graded) | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 4.5 V to 5.5 V at 16 MHz |
| USART Count | 2 | 2 | 2 | 2 | 1 | 1 |
| Low Power Technology | picoPower (P) | picoPower PA (lowest) | standard process | picoPower (P) | picoPower (P) | standard process |
| Temperature Grade | Extended (AQR) | Industrial (AUR) | Industrial (AU) | Industrial (AUR) | Industrial (AUR) | Industrial (AUR) |
Key Differentiators
- Extended temperature grade (AQR suffix) (vs ATMEGA324PA-AUR)
- Two hardware USARTs (vs ATMEGA32-16AUR)
- picoPower process with memory upgrade path (vs ATMEGA164P-20AUR)
- Trade-off: not the lowest-power family member (vs ATMEGA324PA-AUR)
Design Notes
Decouple every supply pin individually: place 100 nF X7R ceramic capacitors within 2 mm of VCC (pins 17, 42) and AVCC (pin 35), each returning to a solid ground plane via short vias. Tie AVCC to VCC through a low-pass LC filter (10 uH ferrite + 100 nF + 10 uF) when ADC accuracy matters, and connect AREF to ground through a 100 nF capacitor when using the internal reference. The 44-TQFP thermal pad is small, but the die dissipates under 100 mW typically - no heatsinking is required.
Reset and ICSP: route the RESET line (pin 44) short with a 10 kOhm pull-up to VCC; long reset traces pick up ESD and cause spurious resets in industrial environments. Keep the ICSP header (MOSI/MISO/SCK/RESET) routed directly to a 2x3 header so field firmware updates remain possible after assembly. Do not remap PB6/PB7 away from the crystal unless using the internal RC oscillator - switching oscillator sources at runtime requires careful fuse settings; wrong fuse configuration (especially clock and JTAGEN) is the most common cause of a bricked ATmega.
Estimated: at 5 V and 20 MHz full activity, an ATmega-class core draws roughly 10-15 mA, dissipating about 50-75 mW - trivial thermally. For battery designs, disable unused peripherals in PRR, use sleep modes between tasks, and prefer the pin-compatible ATMEGA324PA-AUR which lowers both active and power-down currents relative to this P-variant. Enable brown-out detection at the fuse level matching your worst-case VCC droop so EEPROM writes never occur below the minimum safe voltage.
If a crystal is fitted on PB6/PB7, keep the crystal, two 22 pF load capacitors, and return traces within 5 mm of the pins, guarded by ground; route fast SPI and USART1 signals away from the crystal loop. For RS-485 links on the USARTs, add TVS protection and series resistors at the transceiver side, not at the MCU pins. Unused GPIO should be configured as inputs with internal pull-ups or outputs driving low - floating inputs increase supply current and EMI susceptibility.
Compliance Information
Distributor listings (FindIC, DigiKey) describe the ATMEGA324P-20AQR as a GREEN package part, indicating RoHS compliance and lead-free construction. REACH and conflict-minerals status should be confirmed on Microchip's product compliance portal.
