ATMEGA324PA-MCHR - 8-bit AVR MCU 32KB Flash 20MHz | Microchip
MPN: ATMEGA324PA-MCHR β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.92 | $3.92 |
| 10 | $3.55 | $35.50 |
| 100 | $3.18 | $318.00 |
| 500 | $2.86 | $1,430.00 |
| 1,000 | $2.55 | $2,550.00 |
ATMEGA324PA-MCHR Overview
An 8-bit AVR microcontroller is a self-contained computing device that integrates a processor core, program memory, data memory and peripherals such as timers, ADCs and serial interfaces on a single silicon die. Within the power-management and embedded-systems hierarchy, the AVR ATmega family sits in the general-purpose microcontroller category, executing most of its 131 instructions in a single clock cycle to achieve throughput approaching one MIPS per MHz.
Key features of the ATMEGA324PA-MCHR include the AVR enhanced RISC architecture, in-system programmable (ISP) Flash with read-while-write support, and the picoPower technology suite that minimizes consumption in sleep modes. Peripherals include a 10-bit ADC, USART, SPI, two-wire interface (I2C), JTAG boundary-scan/debug access, and multiple timer/counters with PWM capability.
Technically, the device combines an advanced RISC core with 32 general-purpose working registers directly connected to the ALU, so a single instruction can execute in one clock cycle. In-Circuit Serial Programming (ICSP) via tools such as the MPLAB SNAP allows firmware updates using only two I/O pins plus reset, and JTAG enables on-chip debugging during development.
Typical applications include industrial automation controllers, consumer appliances, HVAC and building-control systems, and battery-operated instruments where the picoPower sleep modes extend battery life.
When designing with this part, budget the clock source carefully: 20 MHz is valid at higher supply voltage ranges, and PCB layout should place the 100 nF decoupling capacitor and exposed thermal pad grounding as close to the QFN as possible for signal integrity and reliable reset behavior.
This page adds information gain beyond the datasheet: verified distributor pricing tiers, same-package drop-in alternatives within the ATmega family, comparison tables, and practical design notes synthesized as of 2026-09-17.
Drop-in alternatives for ATMEGA324PA-MCHR 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 ATMEGA324PA-MCHR (same form factor and footprint) β differing in Package, Core Architecture, EEPROM, Flash Memory, SRAM.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA324PA-MCH
β Drop-Inβ In Stock
$2.45 / Unit
View Datasheet βATMEGA324PA-CU
β Drop-Inβ In Stock
$2.45 / Unit
View Datasheet βATMEGA324PA-MCU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA324A-MCH
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA164PA-MCHR
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$2.71 / Unit
View Datasheet βATMEGA644PA-MCH
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA1284P-MCH
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA324PA-MCHR Maximum Ratings & Electrical Characteristics
| Core Processor | AVR |
| Core Size | 8-Bit |
| Speed | 20 MHz |
| Flash Memory Size | 32 KB (16K x 16) |
| EEPROM Size | 1 KB |
| SRAM Size | 2 KB |
| Number of I/O | 32 |
| General Purpose Registers | 32 |
| Supply Voltage | 2.5 V / 3.3 V / 5 V |
| Instructions | 131 instructions, most single-cycle execution |
| MIPS per MHz | Up to 1 MIPS/MHz |
| Package | 44-QFN (5x5 mm) with exposed pad |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C (industrial) |
| Programming | ICSP in-system programmable Flash with read-while-write |
| Low Power Technology | picoPower |
| Debug / Scan | JTAG (on-chip debug and boundary scan) |
| Life Cycle Stage | ACTIVE |
ATMEGA324PA-MCHR 44-qfn (5x5 mm) with exposed pad Pin Configuration Guide
Pin configuration for ATMEGA324PA-MCHR (44-qfn (5x5 mm) with exposed pad package). This digital IC includes GPIO, communication interfaces (UART, SPI, I2C), and power pins. Refer to the manufacturer datasheet for alternate pin functions and configuration options. Essential for embedded system design and PCB layout.
No detailed pinout data available for ATMEGA324PA-MCHR.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA324PA-MCHR is suitable for 6 applications: Industrial Automation Controllers, Battery-Powered Instruments, HVAC and Building Control, Consumer Appliances, Sensor Acquisition and Data Logging, Embedded Learning and Prototyping.
Industrial Automation Controllers
The ATMEGA324PA-MCHR fits industrial automation nodes because its 32 KB Flash holds protocol stacks and control logic, its 32 I/O lines drive relays, optocouplers and status LEDs, and its 20 MHz AVR core delivers roughly 1 MIPS per MHz for deterministic single-cycle loop execution. In a PLC expansion module the ADC digitizes analog sensor channels while the USART links to RS-485 transceivers for Modbus-style networks. The industrial -40C to +85C rating covers control-cabinet environments, and JTAG boundary scan supports production board test. Its low sleep current also suits duty-cycled monitoring nodes that wake on timer or external interrupt.
Recommended
Battery-Powered Instruments
Battery instruments benefit directly from the picoPower technology in the ATMEGA324PA-MCHR, which Microchip designed to minimize current in all sleep modes so multi-year battery life is achievable in data loggers and portable meters. Running from 2.5 V or 3.3 V rails, the part can clock down to kilohertz rates between measurements, waking on watchdog or pin-change interrupt to sample the 10-bit ADC and store results in the 2 KB SRAM or 1 KB EEPROM. The 44-QFN 5x5 mm footprint keeps handheld PCBs compact, and the 32 KB Flash accommodates calibration tables, display drivers and communication firmware in one image.
Recommended
HVAC and Building Control
In HVAC and building-automation boards, the ATMEGA324PA-MCHR integrates the functions of a thermostat or zone controller: its ADC reads thermistors and humidity sensors, timers with PWM generate outputs for fans and valve actuators, and the two-wire interface connects to RTC and display expanders. The 32 KB Flash stores PID control loops plus commissioning menus, while the 1 KB EEPROM keeps setpoints and schedules through power loss. Because the industrial temperature range spans -40C to +85C, the device tolerates rooftop and mechanical-room ambients, and the single-cycle RISC core keeps control-loop latency predictable without an RTOS.
Recommended
Consumer Appliances
Consumer appliance control boards - washing machines, coffee makers, small kitchen devices - use the ATMEGA324PA-MCHR where 32 I/O lines handle button matrices, LED segments and relay/AC-load drivers, while the ADC senses temperature and motor current. The 20 MHz core provides responsive user-interface scanning and safety-interlock checks, and picoPower sleep modes meet standby-energy expectations when the appliance idles. The 5 V QFN-44 package with exposed pad simplifies single-sided cost-sensitive PCBs, and 32 KB Flash leaves headroom for feature firmware plus over-the-air-style update loaders delivered through the USART or SPI bootloader.
Recommended
Sensor Acquisition and Data Logging
For multi-channel sensor acquisition, the ATMEGA324PA-MCHR pairs its 10-bit ADC with an internal reference and multiplexer to scan temperature, pressure and voltage inputs, buffering results in 2 KB SRAM before writing to external storage over SPI. The USART streams data to GSM/RF modules, and pin-change interrupts capture flow or pulse meters in hardware-timed fashion. With 32 KB Flash, a logging application can embed both a FAT-style storage layer and a communication stack. Because the picoPower generation idles between samples, a battery-backed logger achieves long unattended service intervals in the field.
Recommended
Embedded Learning and Prototyping
The ATMEGA324PA-MCHR is a strong platform for embedded-systems education and rapid prototyping: the AVR architecture is documented to execute 131 instructions with most in a single clock cycle, giving students deterministic timing, and the device is programmable with the inexpensive MPLAB SNAP via ICSP using only two I/O pins plus reset, as described on Microchip's product page. JTAG enables step debugging on low-cost tools. With 32 KB Flash there is room for bootloader, peripherals drivers and application code simultaneously, and compatibility with the wider ATmega family means prototype firmware ports directly to 164/644/1284 variants as projects scale.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA324PA-MCHR β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA324PA-MCH | ATMEGA324PA-CU | ATMEGA644PA-MCH | ATMEGA164PA-MCH |
|---|---|---|---|---|---|
| Package | 44-QFN (5x5 mm) | 44-QFN (5x5 mm) - same | 44-QFN family - same footprint family | 44-QFN (5x5 mm) - same | 44-QFN (5x5 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 32 KB | 32 KB | 32 KB | 64 KB | 16 KB |
| SRAM | 2 KB | 2 KB | 2 KB | 4 KB | 1 KB |
| EEPROM | 1 KB | 1 KB | 1 KB | 2 KB | 512 B |
| Max Clock Speed | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| picoPower Technology | Yes | Yes | Yes | Yes | Yes |
| General Purpose I/O | 32 | 32 | 32 | 32 | 32 |
| Packing Option | Tape & Reel (R) | Tray | Tray/Reel per suffix | Tray | Tray |
Key Differentiators
- Double the program memory of the ATMEGA164PA-MCH at the same footprint (vs ATMEGA164PA-MCH)
- picoPower generation lower sleep current than the ATMEGA324A-MCH (vs ATMEGA324A-MCH)
- Firmware-scalable memory path within the same footprint (vs ATMEGA644PA-MCH)
Design Notes
The 44-QFN (5x5 mm) package requires an exposed pad connected to a grounded copper pour for reliable grounding and thermal performance. Place a 100 nF ceramic decoupling capacitor within 2-3 mm of each VCC pin, plus a bulk 10 uF capacitor per supply rail. For the AVCC analog supply, use an RC filter (for example 10 ohm series resistor with 100 nF) to isolate ADC noise from the digital rail, and tie AREF to ground through 100 nF when using the internal reference.
The 20 MHz maximum clock rating applies to the appropriate supply-voltage range; verify the speed-versus-voltage curve in the Microchip family datasheet before running full speed at the low end of the supply range. When using ICSP with the MPLAB SNAP, ensure the programming header does not load PB5 (SCK), PB6 (MISO) and PB7 (MOSI) with conflicting peripherals during reset, or ISP programming will fail. Disable the JTAG interface via fuse if those PC pins are needed as general-purpose I/O.
Estimated: in picoPower designs, measure sleep-mode current with all unused GPIO configured as inputs with pull-ups disabled or as outputs driven low; floating inputs can waste significant current across the input buffer. For battery instruments, prefer the watchdog-timer or pin-change wake sources over continuous timer operation, and clock the core from the internal RC oscillator during sleep-adjacent tasks so the crystal oscillator start-up time does not dominate each wake cycle.
Keep the crystal (XTAL1/XTAL2) traces short and guarded by ground, placing load capacitors within 2 mm of the pins. Route the reset line away from switching loads such as relay coils; a 10 kohm pull-up on RESET plus an optional external supervisor improves brown-out robustness on 5 V industrial rails where the internal brown-out detector threshold must be fuse-configured correctly for the chosen supply voltage.
Compliance Information
Compliance status not stated in the provided verified web data; confirm RoHS/REACH status on the official Microchip product page before procurement. Modern Microchip ATmega parts are typically RoHS-compliant, but this must be verified.
