ATMEGA644P-20MQ - 8-bit AVR MCU 64KB 20MHz VQFN-44 | Microchip
MPN： ATMEGA644P-20MQ ✗ 停產ATMEGA644P-20MQ 概覽
An 8-bit microcontroller is an integrated circuit that combines a processor core, memory, and peripherals such as UARTs, timers, and ADCs on a single chip, forming the lowest tier of the embedded-computing hierarchy (MCU -> embedded processor -> system-on-chip). AVR MCUs like the ATmega644P use an enhanced RISC Harvard architecture in which most of the 131 instructions execute in a single clock cycle, yielding throughput close to 1 MIPS per MHz.
Key features of the ATMEGA644P-20MQ include dual UARTs (2-USART digital communication peripherals), picoPower low-power technology for sleep-current-sensitive designs, an internal RC oscillator that eliminates external crystals in many designs, and 32 general-purpose I/O lines organized as four 8-bit ports (PA-PD). The P suffix denotes the two-USART variant of the ATmega644 family.
The AVR core pairs the RISC engine with peripherhals including 8/16-bit timers with PWM, a 10-bit ADC with multiplexed inputs on port A, TWI (I2C-compatible) and SPI serial interfaces, brown-out detection, and in-circuit serial programming (ICSP) via the reset line using only two device I/O pins. The exposed-pad VQFN-44 package improves thermal performance and grounding over the TQFP variant.
Typical applications include industrial automation nodes, sensor acquisition systems, motor control front-ends, and embedded controllers where 64KB of flash, dual serial ports, and 5V noise immunity are required.
Design consideration: the manufacturer has marked the ATmega644P as a mature product not recommended for new designs; new boards should target the ATmega644PA, which is a pin-compatible drop-in with lower active and sleep current.
This page synthesizes verified distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
直接替換替代品，適用於 ATMEGA644P-20MQ — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： ATMEGA644P-20MQ （相同外形與佔位） — 差異在於 SRAM, Flash Memory, EEPROM, Package, RoHS Status.
ATMEGA644PA-MQ
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
ATMEGA1284P-MQ
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
ATMEGA324P-20MQ
✅ 直接替換 ⚠️ 規格未經驗證聯絡詢價
查看資料表 →ATMEGA164P-20MQ
✅ 直接替換聯絡詢價
查看資料表 →ATMEGA644P-20MQ 最大額定值與電氣特性
| Core Architecture | AVR 8-bit RISC |
| CPU Speed | 20 MHz |
| Throughput | Up to 20 MIPS (1 MIPS per MHz) |
| Flash Program Memory | 64 KB (32K x 16) |
| SRAM | 4 KB (4,096 bytes) |
| EEPROM | 2 KB (2,048 bytes) |
| Operating Voltage | 5 V |
| Number of I/O | 32 |
| Digital Communication Peripherals | 2 UART |
| Oscillator Type | Internal |
| Instructions | 131 powerful instructions, most single-cycle |
| 封裝 | 44-VQFN (7x7 mm) with exposed pad |
| 安裝類型 | Surface Mount |
| Temperature Grade | Industrial, extended temperature |
| Packaging | Tape & Reel (TR) |
| Technology Feature | picoPower low-power, green/RoHS |
| Programming | ICSP via 2 I/O pins + reset, MPLAB SNAP compatible |
| Lifecycle | Mature; NRND - replaced by ATmega644PA |
ATMEGA644P-20MQ 44-vqfn (7x7 mm) with exposed pad 腳位配置指南
ATMEGA644P-20MQ（44-vqfn (7x7 mm) with exposed pad 封裝）的腳位配置。 此數位 IC 包含 GPIO、通訊介面（UART、SPI、I2C）與電源腳位。替代腳位功能與配置選項請參閱製造商資料表。對嵌入式系統設計與 PCB 佈局至關重要。
無詳細腳位定義資料： ATMEGA644P-20MQ.
請參閱 資料表 以查看完整腳位配置。
典型應用
ATMEGA644P-20MQ 適用於 6 應用s: Industrial Automation Nodes, Sensor Acquisition and Data Logging, Embedded Motor Control Front-Ends, 5V Industrial Communication Converters, Hobbyist and Educational Development Boards, Building Automation and Smart Home Controllers.
Industrial Automation Nodes
The ATMEGA644P-20MQ fits industrial automation nodes because its extended industrial temperature grade, 5V noise immunity, and dual UART support robust Modbus RTU and sensor-bus links on noisy factory floors. With 64KB FLASH, 4KB SRAM, and 32 I/O lines, it can host a communication stack plus local control logic without an external memory chip. Used as the main controller of an I/O expansion node or HMI front-end, the two USARTs allow simultaneous connection of a field bus and a diagnostic/debug port; hardware PWM timers drive actuators directly. The trade-off is the lack of Ethernet/CAN - add external converters for those protocols.
推薦
Sensor Acquisition and Data Logging
For battery-powered and line-powered data loggers, the ATMEGA644P-20MQ pairs a 10-bit ADC (8 channels on port A) with picoPower sleep modes that cut standby current dramatically. The 2KB EEPROM retains calibration constants and event counters across power cycles without external NVM, while 64KB FLASH stores logging firmware plus OTA-style bootloaders over either UART. Typical use: place the MCU between the sensor array and an SD or serial memory, sampling at kHz rates; sleep between samples to extend battery life. Because it is NRND, design in the pin-identical ATMEGA644PA-MQ for the same function with lower active current.
推薦
Embedded Motor Control Front-Ends
The ATMEGA644P-20MQ serves as a motor control front-end where its hardware PWM outputs, input-capture timers, and 5V operating margin are decisive. The 16-bit timer with input capture measures encoder feedback with 62.5ns resolution at 16MHz, while multiple PWM channels drive MOSFET half-bridges or servo outputs. Four 8-bit I/O ports give 32 lines for direction relays, limit switches, and status LEDs without expansion. Typical topology: MCU PWM to gate drivers, ADC channels reading current-shunt amplifiers for overcurrent detection. Trade-off: for FOC-grade control, the 20MHz AVR is modest - choose DSP-class MCUs when phase-current loops exceed 10kHz bandwidth.
推薦
5V Industrial Communication Converters
Dual UARTs make the ATMEGA644P-20MQ a natural fit for protocol converter boxes - for example RS232-to-RS485 bridges, sensor-to-Modbus gateways, and printer-interface adapters. With two independent hardware USARTs, the device buffers and translates full-duplex traffic in both directions without bit-banging, and 4KB SRAM provides generous FIFO/ring-buffer headroom for bursty links. The SPI and TWI peripherals add I2C or SPI slave ports so one converter can serve mixed-field devices. At 20MHz it sustains multi-hundred-kbaud links comfortably; above 1Mbaud, verify buffer sizing under worst-case interrupt latency before committing.
推薦
Hobbyist and Educational Development Boards
The ATmega644P family is a mainstay of open-source dev boards (notably Sanguino-class Arduino-compatible boards) because of its 64KB FLASH headroom, Arduino IDE support via AVR cores, and simple ICSP programming through MPLAB SNAP or USBasp tools. Educational designs benefit from the 5V logic that tolerates student wiring mistakes better than 3.3V parts, 32 I/O for experiments, and the internal oscillator that lets boards run crystal-less. The exposed-pad VQFN-44 keeps layouts compact, though hand-soldering the MLF pad is harder than TQFP - prototype with the TQFP ATMEGA644P-20AU before moving to the MQ for production.
推薦
Building Automation and Smart Home Controllers
In building automation, the ATMEGA644P-20MQ acts as a zone controller driving relays, reading wall-unit ADC inputs, and speaking TWI/I2C to displays and RTC modules. The 5V supply matches legacy 12/24V sensor ecosystems through simple dividers, and picoPower sleep modes support always-on occupancy sensing with low average draw. The two UARTs simultaneously handle an RS485 backbone and a service port, while 64KB FLASH leaves room for future firmware features such as scheduling and PID loops. Since the part is NRND, new smart-home designs should adopt the pin-compatible ATMEGA644PA-MQ to secure supply and gain lower sleep current.
推薦
推薦產品摘要
工程參考資料，適用於 ATMEGA644P-20MQ — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | ATMEGA644PA-MQ | ATMEGA1284P-MQ | ATMEGA324P-20MQ | ATMEGA164P-20MQ |
|---|---|---|---|---|---|
| Package | 44-VQFN (7x7 mm) exposed pad | 44-VQFN (7x7 mm) - same | 44-VQFN (7x7 mm) - same | 44-VQFN (7x7 mm) - same | 44-VQFN (7x7 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 64 KB (32K x 16) | 64 KB | 128 KB | 32 KB | 16 KB |
| SRAM | 4 KB | 4 KB | 8 KB | 2 KB | 1 KB |
| EEPROM | 2 KB | 2 KB | 4 KB | 1 KB | 512 B |
| Max CPU Speed | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| UARTs | 2 | 2 | 2 | 2 | 1 |
| Power Efficiency | picoPower (NRND - superseded) | picoPower - lowest current (best) | picoPower | picoPower | picoPower |
| Lifecycle Status | NRND (replaced by ATmega644PA) | Active (recommended for new designs) | Active | Mature | Mature |
主要差異化特點
- Dual UART in the ATmega644P family (對比ATMEGA644-20AU (non-P variant))
- Exposed-pad VQFN for better grounding (對比ATMEGA644P-20AU (TQFP))
- Larger memory than the ATmega324 tier at lower cost than 128KB (對比ATMEGA324P-20MQ)
設計說明
This part is officially NRND: Microchip's datasheet states it is a mature product replaced by the ATmega644PA. Do not start new PCB designs with ATMEGA644P-20MQ; specify ATMEGA644PA-MQ instead, which is pin-to-pin identical and firmware-compatible. For boards already using the 644P, qualify the PA as a second source now, before lead times force an unplanned migration.
The 44-VQFN (7x7 mm) package has an exposed center pad that must be soldered to a ground via array for reliable grounding and thermal performance - it also removes heat and anchors the die. Use 4-6 via connections to the ground plane under the pad and follow the datasheet land pattern exactly. If your assembly house cannot reliably reflow QFN packages, prototype with the pin-compatible TQFP version (ATMEGA644P-20AU) which is easier to inspect and rework.
Operating at 5V is required for the full 20MHz clock; attempting lower supply voltages derates maximum frequency. Decouple both VCC pins and AVCC with 100nF ceramics placed within a few millimeters of each pin, and keep the analog supply (AVCC) filtered via an LC network when ADC accuracy matters. Enable the brown-out detector via fuses so EEPROM writes are protected during supply dips - a corrupted EEPROM during power-down is a common field failure in AVR designs.
ICSP/ISP programming shares the SPI pins (SCK, MOSI, MISO) and reset with application circuitry. Insert series resistors (typically 1k ohm) on these nets so the programmer can drive them without fighting peripheral loads, and avoid using the reset pin as a general I/O (disable with fuses) or in-circuit debugging will be impossible. Keep the ISP header traces short and away from switching loads such as relay coils or PWM motor lines.
合規資訊
Verified web data describes the part as Green/RoHS for the ATmega644P MLF device (FindIC listing: 'Ext Temp, Green, 5V'). REACH, halogen-free, and conflict-minerals status not explicitly stated in provided data.