ATMEGA644P-20MU - 8-bit AVR MCU 20MHz 64KB Flash | Microchip
料号： ATMEGA644P-20MU ✗ 停产| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $6.86 | $6.86 |
| 10 | $6.35 | $63.50 |
| 100 | $5.9 | $590.00 |
| 500 | $5.45 | $2,725.00 |
| 1,000 | $5.02 | $5,020.00 |
ATMEGA644P-20MU 概述
A microcontroller unit (MCU) is a single-chip computer that integrates a processor core, program memory, data memory, and peripherals. In the hierarchy of embedded semiconductors, the ATmega644P sits in the 8-bit microcontroller class of the AVR family, a predecessor to modern AVR DA/DB parts and a sibling to the ATmega328P and ATmega1284P.
Key features include 2KB of EEPROM for non-volatile data storage, two USARTs (the P variant adds a second serial port versus the standard ATmega644), a 10-bit ADC with up to 8 channels, an SPI interface, a two-wire I2C-compatible interface, and a JTAG interface for on-chip debug and boundary scan. The device operates at 5V (Vcc range 4.5V to 5.5V at 20MHz per the industrial temperature, green variant), making it robust for noisy environments where 3.3V MCUs are less tolerant.
Technically, the AVR core uses a Harvard architecture with separate program and data buses and 32 general-purpose working registers directly connected to the ALU. This single-cycle execution model allows deterministic timing that remains popular in bit-banged protocols, motor control loops, and legacy firmware maintenance. Low-voltage capability down to 1.8V is supported by family members at reduced clock rates, per AVR505 application note on migration between ATmega16/32 and ATmega164P/324P/644P.
Typical applications include industrial control panels, sensor acquisition nodes, embedded instrumentation, serial-protocol bridges using the dual USART, and hobby/education platforms that keep large installed firmware bases alive.
A key design consideration: Microchip lists the ATmega644P as a mature product not recommended for new designs, replaced by the pin-compatible ATmega644PA; new boards should target the PA while service designs can continue with this part.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
直接替换替代料： ATMEGA644P-20MU ——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-20MU （相同外形与封装尺寸） ——差异在于 EEPROM, SRAM, Flash Memory, Package, Core Architecture.
快速对比工具——选择替代料号进行并排对比：
ATMEGA644PA-20MU
✅ 直接替换📋 参考替代料（不在目录中）
ATMEGA644P-20MQ
✅ 直接替换✓ 有现货
$2.48 / 个
查看数据手册 →ATMEGA644-20MU
✅ 直接替换📋 参考替代料（不在目录中）
ATMEGA1284P-20MU
✅ 直接替换📋 参考替代料（不在目录中）
ATMEGA644P-20MU 最大额定值与电气特性
| Core Architecture | AVR 8-bit enhanced RISC |
| 最大时钟频率 | 20 MHz |
| Flash Memory | 64 KB (32K x 16) |
| SRAM | 4 KB |
| EEPROM | 2 KB |
| 电源电压 | 4.5 V to 5.5 V (at 20 MHz) |
| USART Count | 2 |
| ADC | 10-bit, up to 8 channels |
| Interfaces | SPI, TWI (I2C-compatible), USART, JTAG |
| 封装 | 44-VQFN (7x7 mm) exposed pad |
| 安装类型 | Surface Mount |
| 工作温度 | Industrial range |
| MIPS Rating | Up to 20 MIPS (1 MIPS/MHz) |
| RoHS 状态 | Green / RoHS compliant |
| Product Status | Mature product; not recommended for new designs, replaced by ATmega644PA |
ATMEGA644P-20MU 44-vqfn (7x7 mm) exposed pad 引脚配置指南
ATMEGA644P-20MU（44-vqfn (7x7 mm) exposed pad 封装）的引脚配置。 该数字 IC 包含 GPIO、通信接口（UART、SPI、I2C）和电源引脚。请参阅制造商数据手册以了解复用引脚功能和配置选项。对嵌入式系统设计和 PCB 布局至关重要。
暂无详细引脚数据： ATMEGA644P-20MU.
请参阅 数据手册 以查看完整引脚配置。
典型应用
ATMEGA644P-20MU 适用于 6 应用s: Industrial Control Panels, Dual-Port Serial Protocol Bridges, Sensor Acquisition Nodes, Embedded Instrumentation, Legacy Firmware Maintenance, Motor and Actuator Control.
Industrial Control Panels
The ATMEGA644P-20MU fits industrial control panels because its 5V supply domain (4.5V to 5.5V at 20MHz) tolerates the electrically noisy environment around relays, contactors, and motor starters far better than 3.3V MCUs. Its 32 general-purpose I/O lines drive front-panel indicators, keypads, and discrete sensor inputs directly, while the 10-bit ADC with 8 channels reads potentiometers, shunt-based current signals, and analog setpoints. The two independent USARTs allow simultaneous connection of an RS-485 Modbus RTU network and a local HMI or debug console. JTAG enables boundary-scan production testing and on-chip debugging of state-machine firmware. Deterministic single-cycle-per-instruction AVR execution simplifies timing-critical scan loops in the millisecond range.
推荐
Dual-Port Serial Protocol Bridges
The defining advantage of the ATMEGA644P-20MU for protocol bridges is its pair of hardware USARTs, absent from the standard ATmega644 and many smaller AVR parts. A bridge can translate RS-232 field traffic to RS-485 or USB-serial backhaul without software USART bit-banging overhead. With 64KB Flash there is ample room for protocol stacks, buffering tables, and firmware update code, while 4KB SRAM provides generous ring buffers: for example, 1KB per port still leaves room for the stack and static state. The 20MHz clock yields up to 20 MIPS, sustaining baud rates up to 115200 on both ports simultaneously with timing margin. Hardware flow control and interrupt-driven reception keep latency deterministic.
推荐
Sensor Acquisition Nodes
For multi-channel sensor acquisition, the ATMEGA644P-20MU combines an 8-channel, 10-bit ADC with 4KB SRAM, enabling storage of moderate sample windows and averaging filters on-chip before transmission. The AVR core's single-cycle ALU makes FIR/IIR filtering math predictable, and the two USARTs let one node stream data upstream while a second port services a local display or configuration terminal. The 2KB EEPROM retains calibration coefficients and sensor offsets across power cycles without external memory. Operating at 5V gives a full-scale ADC input range suited to industrial 0-5V sensors without level shifting. SPI and TWI interfaces connect external precision ADCs or digital sensors such as humidity and pressure devices when higher resolution is required.
推荐
Embedded Instrumentation
Bench instruments, encoders, and test fixtures benefit from the ATMEGA644P-20MU's JTAG interface, which provides in-system debugging and boundary scan - features the popular ATmega328P lacks. The 64KB Flash holds complex measurement routines, lookup tables, and menus, while hardware SPI drives DACs, precision ADCs, and graphical LCD modules. The 20MHz maximum clock supports time-interval measurements with microsecond-class resolution using the 16-bit timers with input capture. Five-volt logic directly drives legacy TTL-level I/O common on older test equipment. The 44-VQFN exposed pad sinks heat from continuous ADC sampling, and the industrial temperature rating suits unconditioned lab and factory environments.
推荐
Legacy Firmware Maintenance
A significant share of ATmega644P demand comes from maintaining installed firmware bases that cannot justify redesign. The ATMEGA644P-20MU keeps binary compatibility with code written for the original ATmega644 while adding the second USART the P variant introduced. Because the ATmega644P family shares the peripheral map described in Microchip application note AVR505 (migration between ATmega16/32 and ATmega164P/324P/644P), code can also be consolidated across family members with minimal changes. Heisener's stock of over 100,000 units provides a practical last-buy window; engineers should pair immediate buys with a validated ATMEGA644PA migration path so spares and production do not depend on NRND inventory indefinitely.
推荐
Motor and Actuator Control
The ATMEGA644P-20MU drives DC and stepper motors using its 16-bit timers with output-compare PWM channels, delivering phase-accurate or fast-PWM waveforms for H-bridge and chopper drivers. Interrupt-driven quadrature decoding on external-interrupt-capable port pins provides closed-loop position feedback, and the 10-bit ADC samples back-EMF or current shunts for torque limiting. The 5V domain directly interfaces common gate-driver and optocoupler inputs, and 32 GPIO lines handle limit switches, enable signals, and status outputs. Flash headroom of 64KB accommodates trapezoidal profiles, acceleration ramps, and fieldbus command parsing on the second USART. Deterministic AVR instruction timing keeps ISR jitter low for smooth low-speed motion.
推荐
推荐产品汇总
工程参考数据： ATMEGA644P-20MU ——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 | ATMEGA644PA-20MU | ATMEGA644P-20MQ | ATMEGA644-20MU | ATMEGA1284P-20MU |
|---|---|---|---|---|---|
| Package | 44-VQFN (7x7 mm) exposed pad | 44-VQFN (7x7 mm) - same | 44-VQFN (7x7 mm) - same | 44-VQFN/MLF-44 - 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 | 64 KB | 64 KB | 128 KB |
| SRAM | 4 KB | 4 KB | 4 KB | 4 KB | 16 KB |
| USART Count | 2 | 2 | 2 | 1 | 2 |
| Max Clock Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Lifecycle Status | Mature / NRND (replaced by ATmega644PA) | Active (recommended) | Mature / NRND | Mature / NRND | Mature family, active sourcing |
关键差异点
- Dual hardware USARTs （对比 ATMEGA644-20MU)
- Higher integration than ATMEGA328P （对比 ATMEGA328P-MU)
- Memory growth path on same footprint （对比 ATMEGA1284P-20MU)
设计说明
The 44-VQFN (7x7 mm) exposed pad is the primary ground and thermal connection. Per Microchip MLF/VQFN package application guidance, the center pad must be soldered to a grounded copper keep-out with a 4x4 via array of 0.3 mm vias to stitch to the internal ground plane. Skipping the exposed-pad connection is a common cause of intermittent ADC noise and reset glitches. Keep the VCC/GND pairs (three of each) each decoupled with 100 nF ceramics placed within 2 mm of the pins.
This 20MHz variant specifies operation in the 5V domain (4.5V to 5.5V at 20MHz per Microchip speed-grade tables); do not clock it at 20MHz below 4.5V, as the family's speed-versus-voltage curve does not guarantee it. Estimated: with 20 mA typical active I/O plus core load at 5V, budget a 100 mA regulator such as an LDO with at least 0.5W dissipation margin when dropping from a 12V rail. Power AVCC separately through an LC filter from VCC to keep ADC noise low.
The ATmega644P is NRND per Microchip - design new boards with the ATMEGA644PA-20MU, which is pin-compatible. Do not confuse 44-VQFN pin numbering with 40-pin DIP ATmega diagrams from hobby documentation; the MLF/VQFN pin map differs. When migrating to the PA, re-verify brown-out detector thresholds and power-consumption margins against the PA datasheet, and confirm that any clock-frequency-dependent timing loops calibrated on the P variant still meet timing after supply-voltage changes.
合规信息
Listed as a green, industrial-temperature QFN/MLF device (green = RoHS/halogen-free per Microchip convention). Formal REACH and conflict-minerals declarations were not found in the provided data.