ATMEGA8A-MNR - 8KB Flash 16MHz AVR MCU | Microchip
部品番号: ATMEGA8A-MNR ✓ 生産中| 数量 | 単価 | 小計 |
|---|---|---|
| 1 | $2.37 | $2.37 |
| 10 | $2.25 | $22.50 |
| 100 | $2.08 | $208.00 |
| 500 | $1.92 | $960.00 |
| 1,000 | $1.78 | $1,780.00 |
ATMEGA8A-MNR 概要
A microcontroller is a single-chip embedded computer that integrates a processor core, program memory, data memory, and peripherals such as timers and communication interfaces. The ATmega8A belongs to the AVR ATmega family, which sits within the broader microcontroller hierarchy alongside 32-bit MCUs and application processors. AVR cores use a Harvard architecture with mostly single-cycle instruction execution, delivering roughly 1 MIPS per MHz of clock.
Key features include 32 general-purpose 8-bit working registers directly connected to the ALU, three flexible timer/counters with compare modes, and read-while-write Flash that supports safe in-system bootloader updates. On-chip peripherals include a programmable serial USART, an SPI interface, and a two-wire (I2C-compatible) TWI interface, covering most common embedded connectivity needs.
Technical depth: the device integrates a 10-bit ADC with up to 8 multiplexed single-ended channels in the QFN package, an internal calibrated RC oscillator (1/2/4/8 MHz) that can eliminate the external crystal in tolerant designs, an analog comparator, a watchdog timer, and power-reduction sleep modes. Programming is via SPI (ISP) or a boot-loader section in Flash, supported by mature toolchains such as Microchip Studio, avr-gcc, and the Arduino IDE-compatible cores.
Typical applications include industrial sensor nodes and small automation controllers that use the 105C extended temperature rating, motor-control and appliance boards using the timer PWM outputs, and hobby/legacy embedded designs where the ubiquitous ATmega8 ecosystem simplifies firmware maintenance.
Design consideration: at 5V the maximum guaranteed clock is 16 MHz, but at reduced VCC the fmax derates per the datasheet frequency-voltage curve, so verify clock speed against supply tolerance when running below 4.5V.
This page synthesizes distributor pricing, drop-in alternatives, pinout data, and practical design notes not consolidated in the manufacturer datasheet. Pricing shown is as of 2026-09-19.
ドロップイン代替品: ATMEGA8A-MNR — 同一パッケージでピン互換。PCBの作り直しが必要な異なるパッケージの部品は除外されています。
このシリーズのバリエーション
同一シリーズでドロップイン互換のモデル: ATMEGA8A-MNR （同一形状・フットプリント） — 相違点: Supply Voltage Range, Timers/Counters, Flash Memory, General Purpose I/O, Maximum Clock Frequency.
クイック比較ツール — 並列比較する代替部品を選択:
ATMEGA8A-MN
✅ ドロップイン✓ 在庫あり
$2.95 / 個
データシートを見る →ATMEGA88PA-MU
✅ ドロップイン✓ 在庫あり
$1.26 / 個
データシートを見る →ATMEGA88A-MU
✅ ドロップイン📋 参考代替品（カタログ未掲載）
ATMEGA88-20MU
✅ ドロップイン ⚠️ 仕様未検証✓ 在庫あり
価格はお問い合わせください
データシートを見る →ATMEGA328P-MNR
✅ ドロップイン📋 参考代替品（カタログ未掲載）
ATMEGA8A-MNR 最大定格＆電気的特性
| Core Processor | AVR |
| Core Size | 8-bit |
| Max Clock Frequency | 16 MHz |
| Flash Memory Size | 8 KB (4K x 16) |
| EEPROM Size | 512 B |
| SRAM Size | 1 KB (1K x 8) |
| Number of I/O | 23 |
| General Purpose Working Registers | 32 x 8-bit |
| Timers/Counters | Two 8-bit, one 16-bit with compare modes |
| Connectivity | USART, SPI, I2C (TWI) |
| ADC Resolution | 10-bit |
| ADC Channels | 8 (TQFP/QFN packages) |
| 動作温度 | -40C to +105C |
| パッケージ / ケース | 32-VFQFN Exposed Pad (MLF), 5x5 mm |
| 実装タイプ | Surface Mount |
| Packaging | Tape & Reel |
| RoHS ステータス | Compliant (Green MLF) |
ATMEGA8A-MNR ピン構成
| ピン 1 | PC6 (RESET) — Reset input / GPIO port C bit 6 |
| ピン 2 | PD0 (RXD) — Port D bit 0 / USART receive |
| ピン 3 | PD1 (TXD) — Port D bit 1 / USART transmit |
| ピン 4 | PD2 (INT0) — Port D bit 2 / external interrupt 0 |
| ピン 5 | PD3 (INT1) — Port D bit 3 / external interrupt 1 |
| ピン 6 | PD4 (T0/XCK) — Port D bit 4 / timer0 clock or USART external clock |
| ピン 7 | VCC — Digital supply voltage |
| ピン 8 | GND — Ground |
| ピン 9 | PB6 (XTAL1/TOSC1) — Port B bit 6 / crystal oscillator input |
| ピン 10 | PB7 (XTAL2/TOSC2) — Port B bit 7 / crystal oscillator output |
| ピン 11 | PD5 (T1/OC0B) — Port D bit 5 / timer1 clock or timer0 output compare B |
| ピン 12 | PD6 (ICP1/AIN0) — Port D bit 6 / timer1 input capture or comparator positive input |
| ピン 13 | PD7 (OC2/AIN1) — Port D bit 7 / timer2 output compare or comparator negative input |
| ピン 14 | PB0 (ICP1/CLKO) — Port B bit 0 / timer1 input capture or clock output |
| ピン 15 | PB1 (OC1A) — Port B bit 1 / timer1 output compare A (PWM) |
| ピン 16 | PB2 (SS/OC1B) — Port B bit 2 / SPI slave select or timer1 output compare B |
| ピン 17 | PB3 (MOSI/OC2) — Port B bit 3 / SPI master out or timer2 output compare |
| ピン 18 | PB4 (MISO) — Port B bit 4 / SPI master in |
| ピン 19 | PB5 (SCK) — Port B bit 5 / SPI clock |
| ピン 20 | AVCC — ADC supply voltage |
| ピン 21 | AREF — ADC reference voltage |
| ピン 22 | GND — Ground |
| ピン 23 | PC0 (ADC0) — Port C bit 0 / ADC channel 0 |
| ピン 24 | PC1 (ADC1) — Port C bit 1 / ADC channel 1 |
| ピン 25 | PC2 (ADC2) — Port C bit 2 / ADC channel 2 |
| ピン 26 | PC3 (ADC3) — Port C bit 3 / ADC channel 3 |
| ピン 27 | PC4 (ADC4/SDA) — Port C bit 4 / ADC channel 4 or TWI data |
| ピン 28 | PC5 (ADC5/SCL) — Port C bit 5 / ADC channel 5 or TWI clock |
| ピン 29 | ADC6 — ADC channel 6 (QFN/MLF packages only) |
| ピン 30 | ADC7 — ADC channel 7 (QFN/MLF packages only) |
| ピン 31 | VCC — Digital supply voltage (second supply pad) |
| ピン 32 | GND — Ground (second ground pad) |
主な用途
ATMEGA8A-MNR の用途: 6 件s: Industrial Sensor Nodes, Small Motor Control and PWM Drives, USBasp Programmers and Hobby Embedded, Home Appliance Control Panels, Battery-Powered IoT Sensor Devices, Legacy AVR Firmware Maintenance and EOL Refresh.
Industrial Sensor Nodes
The ATMEGA8A-MNR's -40C to +105C operating range and integrated 10-bit, 8-channel ADC make it well suited for industrial sensor acquisition nodes such as temperature, pressure, and level transmitters. The ADC pairs with the internal 2.56V reference option or the AREF pin for ratiometric measurement of bridge and NTC sensors, while the USART or TWI bus forwards readings to a PLC gateway. Placed near the sensor front end with the internal 1/2/4/8 MHz RC oscillator, the design eliminates crystals and BOM cost; the trade-off is RC clock accuracy of about +/-2%, so use a crystal when UART timing at high baud rates must be precise.
おすすめ
Small Motor Control and PWM Drives
With two 8-bit timer/counters and one 16-bit timer featuring compare and PWM modes, the ATMEGA8A-MNR generates up to three independent PWM channels for driving small DC motors, fans, and brushless ESC stages through external MOSFET drivers. The 16 MHz clock provides 8-bit PWM resolution at roughly 62.5 kHz, fast enough for quiet, filterless motor control. The 23 GPIO lines handle Hall or limit-switch inputs and status LEDs, while the input-capture-capable timer measures feedback. Keep the MCU ground return separate from motor power returns to the exposed pad to prevent PWM switching noise corrupting ADC readings - a star-ground or split-plane layout is recommended.
おすすめ
USBasp Programmers and Hobby Embedded
The ATMEGA8A-MNR is the standard MCU of the open-source USBasp in-circuit programmer, and its legacy ATmega8 register compatibility keeps thousands of community schematics and firmware builds directly usable. The 8KB Flash stores the USB bit-banged stack plus firmware, and read-while-write Flash allows field updates of the programmer itself. The 5x5 mm QFN suits compact dongle PCBs, and the 16 MHz crystal ties to PB6/PB7 for USB timing. Builders should note that hand-soldering the QFN exposed pad demands a hot-air station or generous via-and-paste pad design; the cut-tape ATMEGA8A-MN variant eases prototype placement.
おすすめ
Home Appliance Control Panels
Appliance user interfaces - oven timers, fan controllers, coffee machines - use the ATMEGA8A-MNR for its low BOM cost, 5V direct drive of LEDs and seven-segment displays, and watchdog timer for autonomous recovery from lockups. The three timer/counters multiplex display segments and debounce keys without CPU-intensive software loops, and the internal RC oscillator removes the crystal, improving vibration reliability. The 105C rating survives enclosed warm environments near heating elements. Because appliances demand long service life, budget the 8KB Flash conservatively for firmware growth; if UI complexity increases, migrate to the pin-compatible ATMEGA88PA-MU or ATMEGA328P-MNR without PCB redesign.
おすすめ
Battery-Powered IoT Sensor Devices
The ATMEGA8A-MNR's six power-reduction sleep modes, including power-down at microamp-level current, suit battery-powered devices such as remote sensor tags and door/window monitors. A typical duty cycle wakes the MCU via watchdog or external interrupt, samples the 10-bit ADC, transmits a short UART or TWI packet to a radio module, then re-enters power-down, yielding multi-year battery life from two AA cells. The 23 GPIOs directly bit-bang sub-GHz or 433 MHz transmitter modules. For best battery life, run from 2.7-3.0V where dynamic power scales quadratically with VCC, and verify the clock-versus-voltage derating curve in the datasheet since 16 MHz operation is not guaranteed at reduced VCC.
おすすめ
Legacy AVR Firmware Maintenance and EOL Refresh
Many shipping products still run ATmega8 firmware, and the ATMEGA8A-MNR is the actively manufactured refresh of the original ATmega8 die, keeping legacy designs in production without code changes. Designs originally built around ATMEGA8-16Mx MLF parts can drop in the ATMEGA8A-MNR with identical pinout, fuses, and register map, refreshing date codes and supply continuity. For supply-chain resilience, qualify the ATMEGA88PA-MU in parallel: it is footprint-identical and provides 25% more clock headroom, but requires the AVR094 migration effort. Maintain ISP programming pads (MOSI/MISO/SCK/RESET) on the PCB so field firmware updates remain possible for the product lifetime.
おすすめ
おすすめ製品の概要
エンジニアリング参考データ: ATMEGA8A-MNR — 比較、設計ガイダンス、コンプライアンス情報。
選定ガイド
代替品との比較
| パラメータ | この製品 | ATMEGA8A-MN | ATMEGA88PA-MU | ATMEGA88A-MU | ATMEGA328P-MNR |
|---|---|---|---|---|---|
| Package | VQFN-32 (5x5 mm) exposed pad | VQFN-32 (5x5 mm) - same | VQFN-32 (5x5 mm) - same | VQFN-32 (5x5 mm) - same | VQFN-32 (5x5 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 8 KB | 8 KB | 8 KB | 8 KB | 32 KB |
| SRAM | 1 KB | 1 KB | 1 KB | 1 KB | 2 KB |
| EEPROM | 512 B | 512 B | 512 B | 512 B | 1 KB |
| Max Clock Frequency | 16 MHz | 16 MHz | 20 MHz | 20 MHz | 20 MHz |
| Firmware Compatibility | Legacy ATmega8 register map | Identical (same die) | ATmega88 map - porting required (AVR094) | ATmega88 map - porting required (AVR094) | ATmega328 map - porting required |
| Operating Temperature | -40C to +105C | -40C to +105C | -40C to +105C | -40C to +85C | -40C to +85C |
主な差別化要因
- Zero-code-change legacy ATmega8 compatibility （vs ATMEGA88PA-MU)
- Extended 105C temperature rating （vs ATMEGA88A-MU)
- Lowest cost for 8KB-class designs （vs ATMEGA328P-MNR)
- Clock headroom when migrating （vs ATMEGA8A-MN)
設計ノート
The 32-pad QFN exposes a central die pad that must be soldered to a PCB ground island for mechanical attachment and thermal dissipation; a solder-mask-defined pad with 4-5 thermal vias to the ground plane is standard practice for hand and reflow assembly. Keep the crystal within 10 mm of PB6/PB7 with short return traces, and place 100 nF decoupling capacitors at each VCC/AVCC pad within 3 mm of the pin. Extend the ISP programming pads (PB3-PB5, PC6) to test points so production programming does not require bed-of-nails access to fine-pitch pads.
ATmega8A maximum clock derates with supply voltage - the datasheet frequency-vs-VCC curve must be consulted when running below 4.5V. Estimated: at 3.3V the safe maximum is approximately 13-14 MHz per the classic AVR derating rule (roughly 1.8 MHz/V above 2.7V); running 16 MHz at 3.3V is out of specification and causes marginal timing failures that appear only over temperature. If a 3.3V design needs full speed, step down to 8 MHz via CLKPR-equivalent fuse settings or choose the picoPower ATMEGA88PA. Decouple AVCC separately with an LC or RC filter (10 ohm + 100 nF) when ADC accuracy matters.
Migrating from ATmega8 to ATmega88-family pin-compatible parts is NOT a firmware drop-in: Microchip application note AVR094 documents changed interrupt vectors, relocated timer control registers, a redesigned ADC mux, and a different EEPROM write sequence. Designs qualified on the ATmega8A should treat ATMEGA88* parts as second sources requiring full re-verification. Also note RESET on PC6 shares the ADC port - if PC6 is configured as GPIO, in-circuit ISP programming is lost unless a reset-delay/timeout fuse strategy is planned. Always verify lock-bit and BOD fuse settings before production flashing.
コンプライアンス情報
FindIC lists the part as Green MLF, tape and reel, indicating RoHS-compliant, lead-free, halogen-free packaging. REACH and conflict-minerals status not stated in provided data.
