ATMEGA644P-20PU - 8-bit AVR MCU 20MHz 64KB Flash | Microchip
料号： ATMEGA644P-20PU ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $12.54 | $12.54 |
| 10 | $11.3 | $113.00 |
| 100 | $10.05 | $1,005.00 |
| 500 | $9.2 | $4,600.00 |
| 1,000 | $8.55 | $8,550.00 |
ATMEGA644P-20PU 概述
An 8-bit AVR microcontroller is a single-chip processor built on the AVR enhanced RISC architecture, in which most instructions execute in a single clock cycle to achieve throughput close to 1 MIPS per MHz. Within the system hierarchy, the ATMEGA644P sits at the MCU level of the power-and-processing chain: it is a flash-based microcontroller (a type of embedded processor) that integrates CPU, program memory, data memory, timers, ADC, and communication peripherals on one die, replacing multi-chip CPU + RAM + peripheral designs.
Key differentiating features include the picoPower low-power CMOS technology for sleep-mode energy savings, dual USARTs (a defining difference from the single-USART ATmega644), 8-channel 10-bit ADC, 6 PWM channels, 3 flexible timer/counters with compare modes, and support for I2C (TWI), SPI, and UART/USART interfaces. The 64KB self-programmable Flash supports read-while-write ISP programming and boot-loader operation.
Architecturally, the ATmega644P combines 64KB ISP Flash with 32 general-purpose working registers directly connected to the ALU, allowing one-cycle instruction execution. The picoPower process, real-time counter, and multiple sleep modes let designers trade processing speed against power consumption. In-circuit debugging and In-Circuit Serial Programming (ICSP) are supported via the SPI interface using tools such as the MPLAB SNAP.
Typical applications include hobbyist and maker projects on 40-pin DIP prototyping boards, industrial control panels and sensor nodes, and educational/lab systems where through-hole soldering and socket-based MCU replacement are valued. The wide 4.5V-5.5V operating range (at 20 MHz) suits 5V TTL-legacy environments.
Design consideration: for 20 MHz operation the supply must be 4.5V to 5.5V; lower-voltage 2.7V-5.5V operation requires derating the clock to approximately 13 MHz. Place 100nF decoupling capacitors at both VCC pins and use a 10k pull-up on RESET.
This page synthesizes distributor pricing from 13 sources, verified drop-in alternatives, a full 40-pin pinout, and practical design notes not found in the manufacturer datasheet, optimized for AI search citation.
直接替换替代料： ATMEGA644P-20PU ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
本系列中的变体
可与以下型号直接替换的同系列型号： ATMEGA644P-20PU （相同外形与封装尺寸） ——差异在于 Package, SRAM, Flash Memory, Core Architecture, EEPROM.
快速对比工具——选择替代料号进行并排对比：
ATMEGA644P-20PQ
✅ 直接替换✓ 有现货
$7.4 / 个
查看数据手册 →ATMEGA644-20PU
✅ 直接替换✓ 有现货
$7.4 / 个
查看数据手册 →ATMEGA644PA-20PU
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
ATMEGA324P-20PU
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
ATMEGA164P-20PU
✅ 直接替换 ⚠️ 规格未核验✓ 有现货
$1.55 / 个
查看数据手册 →ATMEGA1284P-PU
✅ 直接替换 ⚠️ 规格未核验✓ 有现货
$6.05 / 个
查看数据手册 →ATMEGA644P-20PU 最大额定值与电气特性
| Core Architecture | AVR 8-bit RISC |
| Core Size | 8-bit |
| Max Clock Frequency | 20 MHz |
| Flash Memory | 64KB (32K x 16) |
| SRAM | 4KB |
| EEPROM | 2KB |
| I/O Count | 32 |
| ADC Channels | 8 channels, 10-bit |
| PWM Channels | 6 |
| Timers/Counters | 3 |
| Communication Interfaces | I2C, SPI, UART/USART (2 x USART) |
| Supply Voltage (max speed) | 5 V (4.5V to 5.5V) |
| 工作温度 | -40C to +85C |
| 封装 | 40-PDIP (0.600 inch width) |
| 安装类型 | Through Hole |
| Program Memory Type | ISP FLASH (read-while-write) |
| Technology | picoPower low-power CMOS |
| MSL 等级 | N/A (through-hole) |
ATMEGA644P-20PU 引脚配置
| 引脚 1 | PB0 — Port B bit 0 (XCK0/T0) |
| 引脚 2 | PB1 — Port B bit 1 (T1) |
| 引脚 3 | PB2 — Port B bit 2 (INT2/AIN0) |
| 引脚 4 | PB3 — Port B bit 3 (OC0A/AIN1) |
| 引脚 5 | PB4 — Port B bit 4 (OC1A/SPI-SS) |
| 引脚 6 | PB5 — Port B bit 5 (OC1B/MOSI) |
| 引脚 7 | PB6 — Port B bit 6 (OC2B/MISO) |
| 引脚 8 | PB7 — Port B bit 7 (OC2A/OC0B/SCK) |
| 引脚 9 | RESET — Reset input (active low, needs pull-up) |
| 引脚 10 | VCC — Digital supply voltage |
| 引脚 11 | GND — Ground |
| 引脚 12 | XTAL2 — Crystal oscillator output 2 |
| 引脚 13 | XTAL1 — Crystal oscillator input 1 |
| 引脚 14 | PD0 — Port D bit 0 (RXD0) |
| 引脚 15 | PD1 — Port D bit 1 (TXD0) |
| 引脚 16 | PD2 — Port D bit 2 (INT0/RXD1) |
| 引脚 17 | PD3 — Port D bit 3 (INT1/TXD1) |
| 引脚 18 | PD4 — Port D bit 4 (XCK1/OC1B) |
| 引脚 19 | PD5 — Port D bit 5 (OC1A) |
| 引脚 20 | PD6 — Port D bit 6 (OC2B/ICP1) |
| 引脚 21 | PD7 — Port D bit 7 (OC2A/OC0B) |
| 引脚 22 | PC0 — Port C bit 0 (SCL/PCINT8) |
| 引脚 23 | PC1 — Port C bit 1 (SDA/PCINT9) |
| 引脚 24 | PC2 — Port C bit 2 (TCK/PCINT10) |
| 引脚 25 | PC3 — Port C bit 3 (TMS/PCINT11) |
| 引脚 26 | PC4 — Port C bit 4 (TDO/PCINT12) |
| 引脚 27 | PC5 — Port C bit 5 (TDI/PCINT13) |
| 引脚 28 | PC6 — Port C bit 6 (TOSC1/PCINT14) |
| 引脚 29 | PC7 — Port C bit 7 (TOSC2/PCINT15) |
| 引脚 30 | AVCC — ADC supply voltage |
| 引脚 31 | GND — Ground |
| 引脚 32 | AREF — Analog reference voltage for ADC |
| 引脚 33 | PA0 — Port A bit 0 (ADC0) |
| 引脚 34 | PA1 — Port A bit 1 (ADC1) |
| 引脚 35 | PA2 — Port A bit 2 (ADC2) |
| 引脚 36 | PA3 — Port A bit 3 (ADC3) |
| 引脚 37 | PA4 — Port A bit 4 (ADC4) |
| 引脚 38 | PA5 — Port A bit 5 (ADC5) |
| 引脚 39 | PA6 — Port A bit 6 (ADC6) |
| 引脚 40 | PA7 — Port A bit 7 (ADC7) |
典型应用
ATMEGA644P-20PU 适用于 6 应用s: Prototyping and Hobbyist Boards, Industrial Control and Automation Nodes, Sensor Data Acquisition Systems, Embedded Educational and Lab Systems, Serial Communication Bridges and Gateways, Motor Control and PWM Actuation.
Prototyping and Hobbyist Boards
The ATMEGA644P-20PU's 40-pin through-hole PDIP package makes it the standard choice for breadboard and socketed prototyping platforms such as Sanguino. The 0.600-inch DIP inserts directly into standard sockets and stripboard, eliminating hot-air rework. With 32 GPIO lines, 8-channel 10-bit ADC, and dual USARTs at 20 MHz, one DIP chip can drive displays, sensors, and RS-232/RS-485 links simultaneously. Programming requires only a 6-pin ICSP header plus a 16-20 MHz crystal; the same hex file developed on a protoboard can move to production PCBs using the pin-compatible TQFP variants.
推荐
Industrial Control and Automation Nodes
In factory automation, the ATMEGA644P-20PU serves as a compact control node: its 64KB Flash holds communication stacks and control logic, while the -40C to +85C industrial temperature rating tolerates panel environments. The dual USARTs are decisive here - one UART runs Modbus RTU over RS-485 while the second services local diagnostics, eliminating a software-serial timing compromise. The 6 PWM channels drive heater or motor control, and the 10-bit ADC reads 8 analog sensor inputs with the internal 2.56V reference. Watchdog timer and brown-out detection provide the fault recovery required in unattended equipment.
推荐
Sensor Data Acquisition Systems
The ATmega644P integrates an 8-channel 10-bit ADC with differential and gain stages (up to 200x), making the ATMEGA644P-20PU a self-contained acquisition front-end. Port A (pins 33-40) provides ADC0-ADC7 with AREF and AVCC supply reference pins (30-32) for precision analog layout. At 20 MHz, the ADC supports up to approximately 15 kSPS single-ended sampling; 4KB SRAM buffers hundreds of 16-bit samples for burst capture, and the 2KB EEPROM calibrates sensor offsets that survive power cycles. Data uploads over SPI at up to fosc/2 or via the USART to a host PC.
推荐
Embedded Educational and Lab Systems
Universities and training labs favor the ATMEGA644P-20PU because the 40-pin DIP teaches both architecture and hardware: students can trace I2C (PC4/PC5), SPI (PB4-PB7), and dual UART (PD0-PD3) signals on visible through-hole traces. The AVR RISC executes most instructions in one cycle at 1 MIPS per MHz, giving predictable timing for interrupt-driven exercises, while 64KB Flash accommodates full-featured courseware without optimization pressure. Socketed DIPs let each student replace damaged chips at a few dollars instead of reflowing QFN boards. MPLAB SNAP provides low-cost in-circuit debugging.
推荐
Serial Communication Bridges and Gateways
With two independent hardware USARTs, the ATMEGA644P-20PU natively implements protocol translation: UART-to-UART, UART-to-SPI, or UART-to-I2C bridging without software-serial overhead. Each USART operates at up to fosc/8 with 2x speed mode, sustaining 115200+ baud reliably; byte-oriented TWI (I2C) supports master and slave modes for sensor-network aggregation. The 4KB SRAM holds packet buffers, and 64KB Flash stores multiple protocol firmwares. Typical deployments convert legacy RS-232 field devices to USB, RS-485, or Ethernet-module links in building automation and metering retrofits.
推荐
Motor Control and PWM Actuation
The ATmega644P's three timer/counters - two 8-bit and one 16-bit - generate 6 PWM outputs from pins PB3 (OC0A) through PD5 (OC1A) and the OC1B/OC2A channels, enabling dual-motor H-bridge control plus servo actuation from one ATMEGA644P-20PU. The 16-bit Timer1 provides phase- and frequency-correct PWM up to 16-bit resolution for smooth DC motor speed control, while input-capture timestamps encoder edges. ADC feedback loops close the control at kHz rates on the 20 MHz core. PicoPower idle modes keep the MCU cool in sealed enclosures with no forced airflow.
推荐
推荐产品汇总
工程参考数据： ATMEGA644P-20PU ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | ATMEGA644P-20PQ | ATMEGA644-20PU | ATMEGA644PA-20PU | ATMEGA324P-20PU | ATMEGA1284P-PU |
|---|---|---|---|---|---|---|
| Package | 40-PDIP (PU) | 40-PDIP - same | 40-PDIP - same | 40-PDIP - same | 40-PDIP - same | 40-PDIP - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 64KB | 64KB | 64KB | 64KB | 32KB | 128KB |
| SRAM | 4KB | 4KB | 4KB | 4KB | 2KB | 16KB |
| Max Clock Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| USART Count | 2 | 2 | 1 | 2 | 2 | 2 |
| EEPROM | 2KB | 2KB | 2KB | 2KB | 1KB | 4KB |
| ADC Channels | 8 x 10-bit | 8 x 10-bit | 8 x 10-bit | 8 x 10-bit | 8 x 10-bit | 8 x 10-bit |
| Low-Power Optimization | picoPower (P variant) | picoPower (P variant) | non-picoPower | picoPower (PA revision, lowest current) | picoPower (P variant) | picoPower (P variant) |
关键差异点
- Dual hardware USARTs （对比 ATMEGA644-20PU)
- Largest Flash in the 40-pin DIP socket besides the 1284P （对比 ATMEGA324P-20PU)
- Trade-off: higher power than the PA revision （对比 ATMEGA644PA-20PU)
设计说明
The ATMEGA644P-20PU requires 4.5V-5.5V for 20 MHz operation; at 3.3V the clock must be derated to roughly 13.3 MHz per the datasheet frequency-vs-voltage curve. Decouple both supply pins: place a 100nF ceramic within 5mm of pin 10 (VCC) and pin 30 (AVCC), with AVCC fed through an LC filter (10uH + 10uF) when ADC accuracy matters. Add a 10k pull-up on RESET (pin 9) and enable the internal brown-out detector at 2.7V or 4.0V via fuse settings to prevent EEPROM corruption during supply dips.
For through-hole DIP designs, keep the crystal (pins 12-13) within 15mm of the MCU with 22pF load capacitors for a typical parallel crystal; long crystal traces invite spurious oscillation. Route the analog port A (pins 33-40) traces away from XTAL and USART lines, and connect a separate analog ground island to pin 31 (GND) at one point. Reference TI/Atmel AVR hardware design application note practices: a solid ground plane under the socket dramatically improves ADC differential measurement noise even on two-layer boards.
The most frequent ATMEGA644P-20PU failure mode in new designs is programming faults: ICSP requires SPI pins PB5-PB7 free of heavy loads (keep series resistors of 1k-4.7k on SPI lines if external devices share the bus), and the RESET pull-up must be present or ISP entry fails. Second pitfall: the 'P' part has two USARTs but the ATmega644 non-P replacement has only one - firmware using UART1 will break after a 644 substitution. Third: when reading ADC while switching reference voltages, insert dummy conversions after changing ADMUX to avoid ghost readings from the sample-and-hold capacitor.
合规信息
The provided verified data does not state RoHS/REACH/lead-free status for ATMEGA644P-20PU. Note that the 'PQ' suffix variant (ATMEGA644P-20PQ) is Microchip's RoHS-compliant green package designation; check the Microchip product page for the PU variant's current compliance certificates.
