ATMEGA644-20AU - 8-Bit AVR MCU 64KB Flash 20MHz | Microchip
Артикул: ATMEGA644-20AU ✗ Снят с производства| Кол-во | Цена за ед. | Итого |
|---|---|---|
| 1 | $7.75 | $7,75 |
| 10 | $6.98 | $69,80 |
| 100 | $6.21 | $621,00 |
| 500 | $5.59 | $2.795,00 |
| 1.000 | $4.96 | $4.960,00 |
ATMEGA644-20AU Обзор
An AVR microcontroller is a Harvard-architecture 8-bit MCU family that executes most instructions in a single clock cycle using on-chip Flash program memory, SRAM data memory, and EEPROM non-volatile storage. Within the product taxonomy, the ATmega644 sits at AVR MCU -> 8-bit microcontroller -> embedded microcontroller -> integrated circuit, and it is the 64 KB Flash member of the ATmega164/324/644 pin-compatible family.
Key features include 64 KB ISP Flash with read-while-write, 4 KB SRAM, 2 KB EEPROM, two USARTs, a byte-oriented two-wire serial interface, an 8-channel 10-bit ADC, three flexible timer/counters with compare and PWM modes, a programmable watchdog timer, and an internal calibrated RC oscillator. The JTAG interface supports IEEE 1149.1 boundary scan plus on-chip debug and programming.
The device uses a low-power CMOS process with six sleep modes (Idle, ADC Noise Reduction, Power-save, Power-down, Standby, and Extended Standby), enabling battery-powered designs to trade throughput for microamp-level current consumption. The 20 MHz speed grade (-20) supports 2.7 V to 5.5 V operation, while the 10 MHz and 16 MHz grades are restricted to lower supply ranges.
Typical applications include industrial control panels, building automation nodes, motor control front-ends, battery chargers, handheld instruments, and legacy ATmega644 replacement in existing designs. The 32 I/O lines and dual USARTs make it well suited to multi-sensor data acquisition and serial gateway roles.
When designing with this device, decouple every VCC pin with a 100 nF ceramic capacitor placed close to the pin, and keep the AREF pin bypassed with 100 nF plus a 10 uF bulk capacitor when using the ADC. Note that Microchip lists the ATmega644 as a mature product not recommended for new designs, with the ATmega644PA recommended as the successor.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, giving engineers a single reference for procurement and second-source decisions.
Аналоги без доработки для ATMEGA644-20AU — тот же корпус, pin-to-pin совместимость. Компоненты в других корпусах, требующие переработки PCB, исключены.
Варианты в этой серии
Модели той же серии, совместимые без доработки с ATMEGA644-20AU (тот же форм-фактор и посадочное место) — отличается по ADC, Operating Temperature, Serial Interfaces, Timer/Counters, Package.
Инструмент быстрого сравнения — выберите альтернативные компоненты для сравнения бок о бок:
ATMEGA644PA-AU
✅ Прямая замена✓ В наличии
$4.61 / шт.
Открыть даташит →ATMEGA644P-20AU
✅ Прямая замена✓ В наличии
$3.95 / шт.
Открыть даташит →ATMEGA644-20AUR
✅ Прямая замена📋 Справочный аналог (нет в каталоге)
ATMEGA644A-AU
✅ Прямая замена✓ В наличии
$5.4 / шт.
Открыть даташит →ATMEGA1284P-AU
✅ Прямая замена✓ В наличии
$4.65 / шт.
Открыть даташит →ATMEGA644-20AU Максимальные параметры и электрические характеристики
| Core Architecture | 8-bit AVR RISC |
| Program Memory | 64 KB In-System Programmable Flash (32K x 16) |
| SRAM | 4 KB |
| EEPROM | 2 KB |
| Максимальная тактовая частота | 20 MHz |
| Throughput | Up to 20 MIPS at 20 MHz |
| Operating Voltage Range | 2.7 V to 5.5 V |
| General Purpose I/O Pins | 32 |
| General Purpose Working Registers | 32 |
| ADC | 8-channel, 10-bit successive approximation |
| USART Interfaces | 2 |
| Timer/Counters | 2 x 8-bit, 1 x 16-bit with compare and PWM modes |
| Two-Wire Serial Interface | 1 (byte-oriented, I2C compatible) |
| SPI Interface | 1 (master/slave) |
| Корпус | 44-TQFP (10x10 mm) |
| Тип монтажа | Surface Mount |
| Диапазон рабочих температур | -40C to +85C |
| Debug Interface | JTAG (IEEE 1149.1) with on-chip debug |
| Sleep Modes | 6 (Idle, ADC Noise Reduction, Power-save, Power-down, Standby, Extended Standby) |
| Статус RoHS | Compliant |
Конфигурация выводов ATMEGA644-20AU
| Контакт 1 | PB0 — Port B, bit 0 (also XCK0/T0) |
| Контакт 2 | PB1 — Port B, bit 1 (also T1/CLKO) |
| Контакт 3 | PB2 — Port B, bit 2 (also INT2/AIN0) |
| Контакт 4 | PB3 — Port B, bit 3 (also OC0/AIN1) |
| Контакт 5 | PB4 — Port B, bit 4 (also SS/OC0B) |
| Контакт 6 | PB5 — Port B, bit 5 (also MOSI/OC1A) |
| Контакт 7 | PB6 — Port B, bit 6 (also MISO/OC1B) |
| Контакт 8 | PB7 — Port B, bit 7 (also SCK/OC2A) |
| Контакт 9 | RESET — Reset input (active low) |
| Контакт 10 | VCC — Digital supply voltage |
| Контакт 11 | GND — Ground |
| Контакт 12 | XTAL2 — Crystal oscillator output |
| Контакт 13 | XTAL1 — Crystal oscillator input / external clock |
| Контакт 14 | PD0 — Port D, bit 0 (also RXD0) |
| Контакт 15 | PD1 — Port D, bit 1 (also TXD0) |
| Контакт 16 | PD2 — Port D, bit 2 (also RXD1/INT0) |
| Контакт 17 | PD3 — Port D, bit 3 (also TXD1/INT1) |
| Контакт 18 | PD4 — Port D, bit 4 (also OC1B) |
| Контакт 19 | PD5 — Port D, bit 5 (also OC1A) |
| Контакт 20 | PD6 — Port D, bit 6 (also OC2B) |
| Контакт 21 | PD7 — Port D, bit 7 (also OC2A) |
| Контакт 22 | PC0 — Port C, bit 0 (also SCL/ADC0) |
| Контакт 23 | PC1 — Port C, bit 1 (also SDA/ADC1) |
| Контакт 24 | PC2 — Port C, bit 2 (also TCK/ADC2) |
| Контакт 25 | PC3 — Port C, bit 3 (also TMS/ADC3) |
| Контакт 26 | PC4 — Port C, bit 4 (also TDO/ADC4) |
| Контакт 27 | PC5 — Port C, bit 5 (also TDI/ADC5) |
| Контакт 28 | PC6 — Port C, bit 6 (also TOSC1/ADC6) |
| Контакт 29 | PC7 — Port C, bit 7 (also TOSC2/ADC7) |
| Контакт 30 | AVCC — Analog supply voltage for ADC |
| Контакт 31 | GND — Ground |
| Контакт 32 | AREF — Analog reference voltage for ADC |
| Контакт 33 | PA7 — Port A, bit 7 (also ADC7) |
| Контакт 34 | PA6 — Port A, bit 6 (also ADC6) |
| Контакт 35 | PA5 — Port A, bit 5 (also ADC5) |
| Контакт 36 | PA4 — Port A, bit 4 (also ADC4) |
| Контакт 37 | PA3 — Port A, bit 3 (also ADC3) |
| Контакт 38 | PA2 — Port A, bit 2 (also ADC2) |
| Контакт 39 | PA1 — Port A, bit 1 (also ADC1) |
| Контакт 40 | PA0 — Port A, bit 0 (also ADC0) |
| Контакт 41 | VCC — Digital supply voltage |
| Контакт 42 | GND — Ground |
| Контакт 43 | GND — Ground |
| Контакт 44 | GND — Ground |
Типичное применение
ATMEGA644-20AU подходит для 6 применениеs: Industrial Control Panels, Building Automation Nodes, Motor Control Front-Ends, Battery Chargers and Power Management, Handheld Instruments and Data Loggers, Legacy ATmega644 Replacement.
Industrial Control Panels
The ATMEGA644-20AU fits industrial control panels because its 32 general-purpose I/O lines, 8-channel 10-bit ADC, and three timer/counters with PWM can directly drive relays, read analog sensors, and generate control waveforms without external glue logic. Operating from 2.7 V to 5.5 V over -40C to +85C, it interfaces natively with 5 V industrial signaling. In a typical panel controller, the MCU scans digital inputs on ports A-D, samples 4-20 mA loop sensors through the ADC with AREF bypassed by 100 nF plus 10 uF, and updates outputs at a 1 kHz control loop rate. The 64 KB Flash holds the control state machine and Modbus stack, while the 2 KB EEPROM stores calibration constants across power cycles. The trade-off versus a 32-bit MCU is lower math throughput, but the 20 MIPS AVR core is sufficient for deterministic ladder-logic replacement.
Рекомендуется
Building Automation Nodes
The ATMEGA644-20AU suits building automation nodes because its two USARTs and byte-oriented two-wire serial interface allow simultaneous connection to a host bus and local sensor peripherals. A typical node uses one USART for an RS-485 HVAC network and the second for a wireless module, while the I2C-compatible interface reads temperature and humidity sensors. The 8-channel 10-bit ADC monitors occupancy and light-level sensors, and the 16-bit timer provides a real-time counter for scheduling. With 64 KB Flash and 4 KB SRAM, the device hosts a protocol stack plus application logic without external memory. Six sleep modes, including Power-save and Power-down, let the node drop to microamp-level current between polling intervals, extending battery life in wireless installations. The 44-TQFP package keeps the node compact for DIN-rail or wall-box mounting.
Рекомендуется
Motor Control Front-Ends
The ATMEGA644-20AU works as a motor control front-end because its three timer/counters with compare and PWM modes generate complementary drive signals for H-bridge and three-phase inverter stages, while the 8-channel 10-bit ADC samples current-shunt and back-EMF feedback. At 20 MHz the AVR core executes most instructions in one cycle, giving up to 20 MIPS for a field-oriented-control loop running in the low-kilohertz range. The 32 I/O lines accommodate gate-driver enables, fault inputs, and encoder interfaces without port expanders. In a typical implementation, Timer1 produces a 20 kHz center-aligned PWM, the ADC triggers synchronously at the PWM trough to reject switching noise, and the 16-bit timer captures encoder pulses. The main trade-off is that the 10-bit ADC limits current-loop resolution compared with a dedicated motor-control SoC, so oversampling is often used.
Рекомендуется
Battery Chargers and Power Management
The ATMEGA644-20AU is used in battery chargers because its 10-bit ADC monitors cell voltage, charge current, and temperature, while PWM outputs from the 8-bit and 16-bit timers regulate charge current in buck or linear topologies. The 2 KB EEPROM stores battery chemistry profiles and charge-cycle counters without external memory, and the programmable watchdog timer provides a safe shutdown path if firmware hangs. Operating from 2.7 V to 5.5 V, the MCU can be powered directly from the regulated rail of a multi-cell charger. In a typical design, the ADC samples a current-sense amplifier at 1 kHz, the firmware runs a constant-current/constant-voltage state machine, and a USART reports charge status to a host. The trade-off versus an analog charger IC is higher firmware complexity, offset by flexible charge profiles.
Рекомендуется
Handheld Instruments and Data Loggers
The ATMEGA644-20AU fits handheld instruments and data loggers because its 64 KB Flash, 4 KB SRAM, and 2 KB EEPROM provide enough non-volatile storage for sample buffers and calibration tables without external memory devices. The 8-channel 10-bit ADC digitizes sensor signals, the two USARTs stream data to a PC or wireless module, and the JTAG interface allows field firmware updates and debug. Six sleep modes, including ADC Noise Reduction, let the logger sleep between samples at microamp-level current, which is critical for multi-month battery life. In a typical design, the MCU wakes on a timer interrupt, samples four differential channels, stores records in EEPROM, and returns to Power-down. The main trade-off is that the 10-bit ADC and 20 MHz core limit high-speed or high-resolution acquisition compared with a 32-bit instrument MCU.
Рекомендуется
Legacy ATmega644 Replacement
The ATMEGA644-20AU serves as the direct replacement part for legacy ATmega644 designs in industrial and consumer equipment, because it is pin-compatible and functionally identical to the original ATmega644 in the 44-TQFP package. Engineers maintaining long-lifecycle products can substitute it without PCB changes, provided the operating voltage and 20 MHz clock requirements are matched. The device retains the same 64 KB Flash, 4 KB SRAM, 2 KB EEPROM, 32 I/O lines, dual USARTs, and JTAG debug interface as the original family. In practice, replacement requires only firmware re-verification of fuse settings and clock source configuration. Because Microchip lists the ATmega644 as mature and not recommended for new designs, designers should plan a migration path to the ATmega644PA for future builds while using the -20AU to sustain current production.
Рекомендуется
Сводка рекомендуемых товаров
Справочные инженерные данные для ATMEGA644-20AU — сравнение, рекомендации по проектированию и информация о соответствии.
Руководство по выбору
Сравнение с аналогами
| Параметр | Этот товар | ATMEGA644PA-AU | ATMEGA644P-20AU | ATMEGA644-20AUR | ATMEGA1284P-AU |
|---|---|---|---|---|---|
| Package | 44-TQFP (10x10 mm) | 44-TQFP (10x10 mm) - same | 44-TQFP (10x10 mm) - same | 44-TQFP (10x10 mm) - same | 44-TQFP (10x10 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 64 KB | 64 KB | 64 KB | 64 KB | 128 KB |
| SRAM | 4 KB | 4 KB | 4 KB | 4 KB | 16 KB |
| EEPROM | 2 KB | 2 KB | 2 KB | 2 KB | 4 KB |
| Maximum Clock Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Operating Voltage Range | 2.7 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 2.7 V to 5.5 V | 1.8 V to 5.5 V |
| General Purpose I/O Pins | 32 | 32 | 32 | 32 | 32 |
| picoPower Low-Current Technology | No | Yes | Yes | No | Yes |
| Lifecycle Status | Mature / not recommended for new designs | Active (recommended successor) | Active | Mature / not recommended for new designs | Active |
Ключевые отличия
- Mature, widely second-sourced 44-TQFP AVR footprint (против ATMEGA1284P-AU)
- 20 MHz operation across the full 2.7 V to 5.5 V range (против ATMEGA644P-20AU)
- Direct replacement for legacy ATmega644 sockets (против ATMEGA644PA-AU)
Заметки по проектированию
Decouple every VCC pin (pins 10 and 41) with a 100 nF ceramic capacitor placed within a few millimeters of the pin, and add a 10 uF bulk capacitor at the board entry. The AVCC pin (pin 30) must be connected to the same supply through a separate low-pass filter, typically a 10 uH inductor or ferrite bead plus 100 nF, to keep digital switching noise out of the ADC. AREF (pin 32) should be bypassed with 100 nF in parallel with 10 uF when the internal reference is not used. Estimated: at 20 MHz and 5 V, core current is on the order of 10-15 mA, so a 100 nF decoupling network per supply pin is sufficient for the transient currents involved.
Keep the crystal or resonator loop between XTAL1 (pin 13) and XTAL2 (pin 12) as short as possible, with the load capacitors returned to a local ground plane directly beneath the device. Route the RESET line (pin 9) away from switching nodes and add a 100 nF capacitor to ground close to the pin to prevent noise-induced resets. For the 44-TQFP, use a solid ground plane under the package and connect all four GND pins (11, 31, 42, 43) plus the exposed thermal pad area with multiple vias to minimize ground bounce during ADC conversions.
The JTAG pins TCK, TMS, TDO, and TDI are multiplexed with ADC channels on port C (PC2-PC5), so enabling JTAG disables those ADC inputs. If both JTAG debug and all eight ADC channels are required, disable JTAG via the fuse bits after production programming and use the debugWIRE interface instead. Also verify the clock source fuse settings before first power-up: an incorrect CKSEL configuration can leave the device running from the internal RC oscillator at an unexpected frequency, which is a frequent cause of UART baud-rate errors in new designs.
The 44-TQFP package has a low thermal resistance and the ATMEGA644-20AU dissipates well under 100 mW at 20 MHz and 5 V, so no heatsinking is required in normal operation. Estimated: at 5 V and approximately 15 mA core current, power dissipation is about 75 mW, giving a junction temperature rise of only a few degrees Celsius above ambient in still air. Ensure the exposed pad area, if present on the land pattern, is soldered to a ground plane for mechanical robustness rather than thermal reasons.
Информация о соответствии
Distributor listings and comparison data indicate RoHS compliance and lead-free construction for the ATMEGA644-20AU. AEC-Q100 automotive qualification is not applicable to this industrial-grade device. Halogen-free status was not stated in the retrieved data and is marked unknown.