ATMEGA324PA-MCH - 8-bit AVR MCU, 20MHz, 32KB Flash | Microchip
MPN: ATMEGA324PA-MCH β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.85 | $3.85 |
| 10 | $3.46 | $34.60 |
| 100 | $3.05 | $305.00 |
| 500 | $2.74 | $1,370.00 |
| 1,000 | $2.45 | $2,450.00 |
ATMEGA324PA-MCH Overview
An 8-bit AVR microcontroller is a Harvard-architecture RISC processor that executes most instructions in a single clock cycle, sitting in the embedded control hierarchy between tiny 8-pin AVRs and the larger ATmega644/1284 family. MCUs of this class integrate CPU, flash program memory, SRAM, EEPROM, and peripherals on a single die, forming the core of a power management and control system in embedded products.
Key differentiating features include Microchip picoPower technology for ultra-low sleep-mode consumption, an advanced RISC core with 131 instructions and 32x8 general-purpose working registers, an on-chip 2-cycle hardware multiplier, and full in-system programmability (ISP) with read-while-write flash capability. Two 8-bit timers, one 16-bit timer, a 10-bit ADC, USART, SPI, and two-wire interface (I2C) peripherals round out the feature set.
Architecturally, the device achieves CPU throughput approaching one million instructions per second (MIPS) per megahertz, allowing designers to optimize power consumption versus processing speed. The picoPower variant (the P-suffix die) supports multiple sleep modes including Idle, ADC Noise Reduction, Power-save, Power-down, Standby, and Extended Standby.
Typical applications include industrial automation sensors and actuators, consumer appliance control boards, battery-powered instrumentation, and building-control or HVAC systems, where the 32 KB flash provides ample headroom for protocol stacks and the VQFN-44 footprint saves board area versus TQFP.
For reliable operation, provide a stable 2.7V to 5.5V supply, decouple VCC and AVCC with 100 nF ceramics placed close to the pads, and keep the reset line properly pulled up. Flash endurance of 10,000 write cycles should be respected in data-logging designs.
This page synthesizes distributor availability, drop-in alternatives, comparison tables, and practical design notes not found in the manufacturer datasheet, with pricing as of 2026-09-17.
Drop-in alternatives for ATMEGA324PA-MCH 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-MCH (same form factor and footprint).
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA324PA-MCHR
β Drop-Inβ In Stock
$2.55 / Unit
View Datasheet βATMEGA324P-20MU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA324A-MU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA324PA-MCH Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Flash Memory | 32 KB (16K x 16) ISP Flash |
| EEPROM | 1 KB |
| SRAM | 2 KB |
| Maximum Clock Frequency | 20 MHz |
| Throughput | Up to 20 MIPS at 20 MHz |
| Operating Voltage Range | 2.5 V to 5.5 V |
| General Purpose I/O | 32 I/O lines |
| Package | 44-QFN (5x5 mm) with exposed pad |
| Mounting Type | Surface Mount |
| Instruction Set | 131 instructions, most single-cycle |
| Working Registers | 32 x 8 general purpose |
| Multiplier | On-chip 2-cycle multiplier |
| Low Power Technology | picoPower |
| Programmability | In-System Programmable (ISP), read-while-write |
| Supply Voltage Options | 2.5 V / 3.3 V / 5 V |
ATMEGA324PA-MCH Pin Configuration
| Pin 1 | PB0 β Port B bit 0 (XCK/T0) |
| Pin 2 | PB1 β Port B bit 1 (T1) |
| Pin 3 | PB2 β Port B bit 2 (AIN0/INT2) |
| Pin 4 | PB3 β Port B bit 3 (AIN1/OC0) |
| Pin 5 | PB4 β Port B bit 4 (SS) |
| Pin 6 | PB5 β Port B bit 5 (MOSI) |
| Pin 7 | PB6 β Port B bit 6 (MISO) |
| Pin 8 | PB7 β Port B bit 7 (SCK/OC2) |
| Pin 9 | RESET β Active-low reset input |
| Pin 10 | VCC β Digital supply voltage |
| Pin 11 | GND β Ground |
| Pin 12 | XTAL2 β Oscillator output |
| Pin 13 | XTAL1 β Oscillator input |
| Pin 14 | PD0 β Port D bit 0 (RXD) |
| Pin 15 | PD1 β Port D bit 1 (TXD) |
| Pin 16 | PD2 β Port D bit 2 (INT0) |
| Pin 17 | PD3 β Port D bit 3 (INT1/OC2B) |
| Pin 18 | PD4 β Port D bit 4 (XCK/T0) |
| Pin 19 | PD5 β Port D bit 5 (OC1A) |
| Pin 20 | PD6 β Port D bit 6 (ICP1) |
| Pin 21 | PD7 β Port D bit 7 (OC2A) |
| Pin 22 | PC0 β Port C bit 0 (SCL) |
| Pin 23 | PC1 β Port C bit 1 (SDA) |
| Pin 24 | PC2 β Port C bit 2 (TCK) |
| Pin 25 | PC3 β Port C bit 3 (TMS) |
| Pin 26 | PC4 β Port C bit 4 (TDO) |
| Pin 27 | PC5 β Port C bit 5 (TDI) |
| Pin 28 | PC6 β Port C bit 6 (TOSC1) |
| Pin 29 | PC7 β Port C bit 7 (TOSC2) |
| Pin 30 | AVCC β Analog supply voltage (ADC power) |
| Pin 31 | GND β Ground |
| Pin 32 | AREF β Analog reference voltage for ADC |
| Pin 33 | PA0 β Port A bit 0 (ADC0) |
| Pin 34 | PA1 β Port A bit 1 (ADC1) |
| Pin 35 | PA2 β Port A bit 2 (ADC2) |
| Pin 36 | PA3 β Port A bit 3 (ADC3) |
| Pin 37 | PA4 β Port A bit 4 (ADC4) |
| Pin 38 | PA5 β Port A bit 5 (ADC5) |
| Pin 39 | PA6 β Port A bit 6 (ADC6) |
| Pin 40 | PA7 β Port A bit 7 (ADC7) |
| Pin 41 | VCC β Digital supply voltage (MLF center pad ring) |
| Pin 42 | GND β Ground (MLF center pad ring) |
| Pin 43 | GND β Ground (exposed pad - must be soldered to ground plane) |
| Pin 44 | VCC β Digital supply voltage (MLF center pad ring) |
Typical Applications
ATMEGA324PA-MCH is suitable for 6 applications: Industrial Automation Control, Battery-Powered Instruments, Consumer Appliance Control Boards, Building Automation and HVAC, Sensor and Data-Acquisition Nodes, Hobbyist and Educational Embedded Platforms.
Industrial Automation Control
The ATMEGA324PA-MCH fits industrial automation nodes because its 32 GPIO lines and 20 MHz AVR core handle sensor scanning, relay sequencing, and Modbus-style serial protocols within a single chip. The USART with hardware flow control links directly to RS-485 transceivers, while the TWI interface services I2C sensors and EEPROM expansion. Its industrial-grade 44-QFN package with exposed pad provides solid ground integrity on electrically noisy factory floors, and the 32 KB flash leaves headroom for firmware updates. Running the core at 8-16 MHz with the picoPower sleep modes between scan cycles reduces average board power, valuable in always-on monitoring cabinets where passive cooling is the norm.
Recommended
Battery-Powered Instruments
Because this is a picoPower device supporting Power-down and Power-save sleep modes from a 2.5 V to 5.5 V supply, the ATMEGA324PA-MCH is well suited to portable meters, data loggers, and handheld test tools. The 10-bit ADC samples battery voltage, thermistors, or bridge sensors directly, and the 1 KB EEPROM stores calibration constants across 100,000 write cycles. Designers typically clock the part from a 32.768 kHz crystal in Power-save mode between measurements, waking via timer or watchdog interrupt. The 44-QFN 5x5 mm footprint keeps the PCB compact for enclosure-constrained instruments while the exposed pad simplifies thermal and ground design on two-layer boards.
Recommended
Consumer Appliance Control Boards
White-goods and small-appliance control boards benefit from the ATMEGA324PA-MCH's balance of memory and cost: 32 KB flash hosts display drivers, touch-debounce logic, and communication stacks simultaneously, while the 2 KB SRAM buffers menu structures and state machines. TWI (I2C) drives remote display or capacitive-touch controllers, and the 16-bit timer generates precise PWM for motor or heater triac control. The 5 V tolerant architecture eliminates level-shifting in classic appliance supplies. The 44-QFN package withstands the vibration and thermal cycling typical of appliance environments better than fine-pitch leadless alternatives, and Microchip's long-lifecycle MCU policy supports multi-year production programs.
Recommended
Building Automation and HVAC
Thermostats, damper controllers, and zone valve actuators use the ATMEGA324PA-MCH for its combination of low standby power and robust peripherals. The picoPower sleep modes keep wall-battery-backed thermostats alive through outages, while TWI links to humidity and temperature sensors and the USART to occupancy-network backbones. Its 20 MHz performance executes PID loops for motorized dampers with ample margin at reduced clock rates. Designers exploit the 10-bit ADC for NTC thermistor networks and the 16-bit timer for precise blower PWM. The exposed-pad QFN-44 dissipates modest drive-stage heat and its 32 GPIO directly drive LCD segments, keypads, and triac drivers without port expanders.
Recommended
Sensor and Data-Acquisition Nodes
Distributed sensing installations leverage the ATMEGA324PA-MCH's 10-bit ADC, 32 GPIO, and serial interfaces to digitize up to eight differential analog channels and stream results over USART, SPI, or TWI. The ADC Noise Reduction sleep mode suppresses digital-core jitter during conversions, improving effective resolution on slow-moving signals such as weight, pressure, and level. The 2 KB SRAM supports ring buffers for burst capture, and 1 KB EEPROM logs calibration and configuration across power cycles. Flash read-while-write allows field firmware updates without host downtime, and the picoPower die extends battery or energy-harvesting node lifetime in remote deployments.
Recommended
Hobbyist and Educational Embedded Platforms
The ATmega324 family remains popular in education and maker platforms because AVR tools are free, well documented, and Arduino-compatible via third-party cores. The ATMEGA324PA-MCH offers the same familiar AVR instruction set as the ATmega328P but doubles the I/O to 32 pins and adds richer timers, letting students build multi-peripheral projects such as robots, instrument clusters, and small CNC controllers on one chip. ISP programming through the SPI header requires only a low-cost programmer. The 5 V operation keeps lab power supplies simple, and the exposed-pad QFN teaches professional SMT assembly practice for advanced coursework.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA324PA-MCH β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA324PA-MCHR | ATMEGA324P-20MU | ATMEGA324A-MU |
|---|---|---|---|---|
| Package | 44-QFN (5x5 mm) | 44-QFN (5x5 mm) - same | 44-QFN (5x5 mm) - same | 44-QFN (5x5 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology (Atmel legacy) | Microchip Technology (Atmel legacy) |
| Flash Memory | 32 KB | 32 KB | 32 KB | 32 KB |
| SRAM | 2 KB | 2 KB | 2 KB | 2 KB |
| EEPROM | 1 KB | 1 KB | 512 B | 1 KB |
| Max Clock | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| picoPower Low-Power Technology | Yes | Yes | No | No |
| Operating Voltage | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 4.5 V to 5.5 V | 2.5 V to 5.5 V |
| Automotive Grade | No | No | No | No |
Key Differentiators
- picoPower ultra-low sleep-mode consumption (vs ATMEGA324P-20MU)
- 1 KB EEPROM vs 512 B (vs ATMEGA324P-20MU)
- Exposed-pad 5x5 mm QFN saves 60% board area vs TQFP (vs ATMEGA324PA-CU)
- Trade-off: QFN soldering difficulty (vs ATMEGA324PA-AUR)
Design Notes
The 44-QFN package includes an exposed pad (pin 43 region) that must be soldered to a grounded thermal land. Follow the IPC-recommended pattern: an array of thermal vias (typically 4-5) connecting the pad to internal ground planes, with solder-paste apertures reduced 20-30% to avoid voiding and die float during reflow. Under-volumed exposed-pad joints are the most common assembly defect on QFN AVRs, causing intermittent ground faults that mimic firmware bugs. Per the Microchip datasheet mechanical drawings, the 5x5 mm body has 0.5 mm pitch perimeter pads requiring no-clean SAC305 solder with optimized stencil apertures.
Decouple VCC (pins 10 and 41/44) and AVCC (pin 30) each with 100 nF ceramic capacitors placed within 2-3 mm of the pads, plus one bulk 4.7-10 uF capacitor per supply rail. Tie AVCC to VCC through an RC filter (10 ohm resistor plus 100 nF) when ADC accuracy matters, and keep AREF (pin 32) decoupled with a 100 nF capacitor when using the internal reference. Estimated: at 5 V and 20 MHz, active-mode supply current of roughly 10-15 mA (typical class figure - verify against datasheet electrical characteristics) produces only 50-75 mW dissipation, so no heatsinking is needed.
Three frequent mistakes with this device: (1) leaving RESET (pin 9) un-pulled - always add a 10k pull-up to VCC, because the reset pin is sensitive and ISP programming fails without it; (2) exceeding the flash 10,000 write-cycle endurance by self-programming in data-logging loops - move frequent data to the 1 KB EEPROM or external memory instead; (3) assuming maximum 20 MHz is available at 2.7 V - the AVR speed/voltage curve derates maximum frequency at low VCC, so consult the speed-grade graph in the Microchip family data sheet (DS40002070) before finalizing the clock source.
Route the XTAL1/XTAL2 crystal traces (pins 12-13) as short as possible - under 10 mm - and guard them with a ground ring, since the AVR Pierce oscillator is sensitive to capacitive pickup that causes startup failures at cold temperatures. Use load capacitors matched to the crystal specification (typically 12-22 pF) and place the crystal on the same PCB layer as the MCU. Keep ISP-programming header traces (PB5-PB7, RESET) under 100 mm and series-terminate SPI clocks over 20 cm to prevent programming corruption.
Compliance Information
Compliance status not explicitly stated in the provided web data. Microchip standard production parts are typically RoHS-compliant, but verify against the official Microchip product page certificate before procurement.
