ATMEGA8-16AI - 8-Bit AVR MCU 16MHz 8KB Flash | Microchip
MPN: ATMEGA8-16AI β End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.85 | $3.85 |
| 10 | $3.46 | $34.60 |
| 100 | $3.08 | $308.00 |
| 500 | $2.77 | $1,385.00 |
| 1,000 | $2.46 | $2,460.00 |
ATMEGA8-16AI Overview
An AVR microcontroller is a single-chip computer built around the AVR enhanced RISC architecture, a Harvard-architecture 8-bit core that executes most instructions in a single clock cycle from 32 general-purpose working registers. Within the semiconductor taxonomy, the ATmega8 sits at the entry level of the AVR ATmega family, which itself belongs to the broader class of 8-bit microcontrollers, embedded processors, and finally integrated circuits. The ATmega8 was the original device that popularized the AVR platform in hobbyist and industrial designs, and its register map and instruction set remain the reference point for later ATmega parts.
Key differentiators of the ATMEGA8-16AI include 8 KB self-programming Flash with an endurance rating of 10,000 write/erase cycles, 130 powerful instructions with most executing in a single clock cycle, 32 programmable I/O lines, and a wide 2.7 V to 5.5 V operating range. The 16 MHz maximum frequency at 4.5 V to 5.5 V makes it suitable for timing-sensitive control loops, while the 10-bit ADC with 15 kSPS conversion rate supports direct analog sensor interfacing without external converters.
The device uses Atmel's high-density nonvolatile memory process technology and a fully static core that can be clocked down to DC, enabling aggressive power reduction in battery-powered designs. Six sleep modes, including Idle, ADC Noise Reduction, Power-save, Power-down, Standby, and Extended Standby, allow the MCU to trade throughput for current consumption, with Power-down current in the low microampere range.
Typical applications include industrial motor and relay control, battery chargers and power supplies, handheld instrumentation, home automation nodes, and legacy embedded control boards. The integrated USART, SPI, and TWI interfaces make it a natural fit for designs that must bridge analog sensors to a host processor or field bus.
When designing with the ATMEGA8-16AI, note that the TQFP-32 package requires careful decoupling of AVCC and VCC, and that the internal RC oscillator should be calibrated if used as the system clock. The device is obsolete per distributor lifecycle data, so designs should plan for a migration path to the pin-compatible ATmega8A or the ATmega88 family.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, giving engineers a single reference for replacement planning and layout decisions.
Drop-in alternatives for ATMEGA8-16AI β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with ATMEGA8-16AI (same form factor and footprint) β differing in EEPROM, General Purpose Working Registers, Maximum Clock Frequency, Package, Throughput.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA8A-AU
β Drop-Inβ In Stock
$1.31 / Unit
View Datasheet βATMEGA8-16AU
β Drop-Inβ In Stock
$1.78 / Unit
View Datasheet βATMEGA8-16AUR
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA88-20AU
β Drop-Inβ In Stock
$2.33 / Unit
View Datasheet βATMEGA88-20AUR
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA8-16AC
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA8-16AI Maximum Ratings & Electrical Characteristics
| Core Processor | AVR 8-bit RISC |
| Program Memory Size | 8 KB (4K x 16) Flash |
| Program Memory Type | In-System Programmable Flash |
| Flash Endurance | 10,000 write/erase cycles |
| SRAM | 1 KB |
| EEPROM | 512 Bytes |
| Maximum Clock Frequency | 16 MHz |
| Throughput | Up to 16 MIPS at 16 MHz |
| Operating Voltage Range | 2.7 V to 5.5 V |
| Speed Grade Voltage | 16 MHz at 4.5 V to 5.5 V |
| Instruction Set | 130 powerful instructions, most single-clock cycle |
| General Purpose Working Registers | 32 x 8-bit |
| I/O Lines | 32 programmable I/O lines |
| ADC | 10-bit, 6 or 8 channels, 15 kSPS |
| Timers | Two 8-bit, one 16-bit with separate prescaler |
| Serial Interfaces | USART, SPI, Two-wire (I2C-compatible) |
| Internal Oscillator | Calibrated RC oscillator |
| Package | 32-TQFP (7x7 mm) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C |
| RoHS Status | Compliant |
ATMEGA8-16AI Pin Configuration
| Pin 1 | PB0 β Port B, bit 0 (ICP1 input capture) |
| Pin 2 | PB1 β Port B, bit 1 (OC1A output compare) |
| Pin 3 | PB2 β Port B, bit 2 (SS, slave select) |
| Pin 4 | PB3 β Port B, bit 3 (MOSI) |
| Pin 5 | PB4 β Port B, bit 4 (MISO) |
| Pin 6 | PB5 β Port B, bit 5 (SCK) |
| Pin 7 | PB6 β Port B, bit 6 (XTAL1) |
| Pin 8 | PB7 β Port B, bit 7 (XTAL2) |
| Pin 9 | RESET β Reset input (active low) |
| Pin 10 | VCC β Digital supply voltage |
| Pin 11 | GND β Ground |
| Pin 12 | XTAL2 β Crystal oscillator output |
| Pin 13 | XTAL1 β Crystal oscillator input |
| Pin 14 | PD0 β Port D, bit 0 (RXD) |
| Pin 15 | PD1 β Port D, bit 1 (TXD) |
| Pin 16 | PD2 β Port D, bit 2 (INT0) |
| Pin 17 | PD3 β Port D, bit 3 (INT1) |
| Pin 18 | PD4 β Port D, bit 4 (OC1B) |
| Pin 19 | PD5 β Port D, bit 5 (OC0) |
| Pin 20 | PD6 β Port D, bit 6 (OC2) |
| Pin 21 | PD7 β Port D, bit 7 |
| Pin 22 | PC0 β Port C, bit 0 (ADC0) |
| Pin 23 | PC1 β Port C, bit 1 (ADC1) |
| Pin 24 | PC2 β Port C, bit 2 (ADC2) |
| Pin 25 | PC3 β Port C, bit 3 (ADC3) |
| Pin 26 | PC4 β Port C, bit 4 (ADC4) |
| Pin 27 | PC5 β Port C, bit 5 (ADC5) |
| Pin 28 | PC6 β Port C, bit 6 (RESET) |
| Pin 29 | AVCC β Analog supply voltage for ADC |
| Pin 30 | AREF β Analog reference voltage |
| Pin 31 | GND β Ground |
| Pin 32 | ADC7 β ADC channel 7 (TQFP only) |
Typical Applications
ATMEGA8-16AI is suitable for 6 applications: Industrial Motor and Relay Control, Battery Chargers and Power Supplies, Handheld Instrumentation, Home Automation and IoT Nodes, Legacy Embedded Control Boards, Educational and Prototyping Platforms.
Industrial Motor and Relay Control
The ATMEGA8-16AI fits industrial motor and relay control because its 32 programmable I/O lines and three timer/counters (two 8-bit, one 16-bit) can generate PWM and dead-time signals directly without external logic. At 16 MHz it executes most AVR instructions in a single clock cycle, giving deterministic loop timing for commutation and soft-start ramps. The 10-bit ADC samples current-sense shunts or potentiometer feedback at up to 15 kSPS, while the USART provides a Modbus-style serial link to a supervisory controller. A typical implementation drives opto-isolated TRIAC or relay gates from PORTB and PORTC, with the 16-bit Timer1 in fast PWM mode setting duty cycle. The main trade-off is that the 8 KB Flash limits complex field-oriented control algorithms, so the device suits brushed DC, stepper, and simple induction motor drives rather than high-performance FOC.
Recommended
Battery Chargers and Power Supplies
The ATMEGA8-16AI is well suited to battery charger and switch-mode power supply control because its 10-bit ADC monitors battery voltage, charge current, and temperature while the 16-bit timer generates the PWM drive for the power stage. The 2.7 V to 5.5 V supply range allows direct operation from a regulated 5 V auxiliary rail, and the internal calibrated RC oscillator can run the control loop without an external crystal, reducing BOM cost. In a typical lithium-ion charger, the ADC samples a current-sense resistor at 15 kSPS, firmware implements CC/CV state machine logic, and the USART reports status to a host. The trade-off is that the 8 KB Flash and 1 KB SRAM constrain advanced algorithms such as digital compensation with high-order filters, so the part is best for chargers up to a few hundred watts.
Recommended
Handheld Instrumentation
Handheld instrumentation benefits from the ATMEGA8-16AI's integrated 10-bit ADC, low Power-down current, and 2.7 V operation, which allow multi-month battery life in portable measurement tools. The 6 or 8 ADC channels accept thermocouple amplifiers, strain-gauge bridges, or resistive sensors directly, and the two-wire serial interface drives small I2C OLED or LCD displays. Six sleep modes, including ADC Noise Reduction, let firmware average readings with minimal digital noise, improving effective resolution beyond the nominal 10 bits. A typical design uses Timer1 for a precise sample interval, the USART for data logging to a PC, and the internal RC oscillator to save board space. The limitation is that 1 KB SRAM restricts large sample buffers, so streaming or on-the-fly processing is preferred over block capture.
Recommended
Home Automation and IoT Nodes
The ATMEGA8-16AI serves home automation and IoT sensor nodes because its USART, SPI, and two-wire interfaces connect directly to RF transceivers, Ethernet controllers, and sensor ICs without glue logic. The 32 I/O lines handle relays, buttons, LEDs, and PIR or reed sensors, while the 10-bit ADC reads light, temperature, and humidity analog outputs. Running from 2.7 V to 5.5 V, the MCU can share a rail with 3.3 V radios when the clock is reduced to about 8 MHz, and Power-save mode keeps average current low enough for battery nodes. A common topology uses the SPI bus for an RF module, the USART for a gateway link, and Timer2 for a wake-up tick. The 8 KB Flash is adequate for protocol stacks such as simple Zigbee or proprietary sub-GHz framing, but not for full TCP/IP stacks.
Recommended
Legacy Embedded Control Boards
The ATMEGA8-16AI remains relevant for legacy embedded control boards because its register map and instruction set are the reference point for the original AVR ATmega8 platform, so existing firmware and programmers work unchanged. Boards designed around the 32-TQFP footprint can continue production using remaining stock or the pin-compatible ATMEGA8A-AU, avoiding a full PCB respin. The device's 8 KB Flash, 1 KB SRAM, and 512-byte EEPROM match the original resource budget, and the USART/SPI/TWI set supports the same peripherals as the original design. The key consideration is lifecycle: because the part is obsolete, sustaining engineers should qualify the ATmega8A or ATmega88 as a second source and validate firmware against Microchip application note AVR094 before the last-time-buy window closes.
Recommended
Educational and Prototyping Platforms
The ATMEGA8-16AI is a classic educational and prototyping MCU because its AVR core, 8 KB Flash, and 32 I/O lines map directly onto the Arduino-era learning ecosystem, and the 32-TQFP package is easy to route on two-layer boards. Students can program it through the SPI-based in-system programming interface using low-cost USB programmers, and the internal RC oscillator removes the need for an external crystal in first experiments. The 10-bit ADC, timers, and USART let learners explore analog input, PWM, and serial communication in one device. The trade-off is that the obsolete lifecycle status makes it a poor choice for new teaching kits; educators should standardize on the ATMEGA8A-AU or ATMEGA88-20AU, which are pin-compatible and remain in active production.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA8-16AI β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA8A-AU | ATMEGA8-16AU | ATMEGA88-20AU |
|---|---|---|---|---|
| Package | 32-TQFP (7x7) | 32-TQFP (7x7) - same | 32-TQFP (7x7) - same | 32-TQFP (7x7) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 8 KB (4K x 16) | 8 KB (4K x 16) | 8 KB (4K x 16) | 8 KB (4K x 16) |
| SRAM | 1 KB | 1 KB | 1 KB | 1 KB |
| EEPROM | 512 Bytes | 512 Bytes | 512 Bytes | 512 Bytes |
| Maximum Clock Frequency | 16 MHz | 16 MHz | 16 MHz | 20 MHz |
| Operating Voltage | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V |
| Lifecycle Status | Obsolete | Active | Obsolete | Active |
| ADC Resolution | 10-bit, 6/8 channels | 10-bit, 6/8 channels | 10-bit, 6/8 channels | 10-bit, 6/8 channels |
| Serial Interfaces | USART, SPI, TWI | USART, SPI, TWI | USART, SPI, TWI | USART, SPI, TWI |
Key Differentiators
- Active lifecycle status (vs ATMEGA8-16AI)
- Higher maximum clock frequency (vs ATMEGA8-16AI)
- Identical electrical core with different ordering suffix (vs ATMEGA8-16AU)
Design Notes
Decouple VCC and AVCC separately with 100 nF ceramic capacitors placed within 5 mm of the pins, and add a 10 uF bulk capacitor on the board rail. AVCC must be connected even when the ADC is unused, and AREF should be tied to a clean reference or to AVCC through a low-pass filter. Estimated: at 16 MHz and 5 V, core current is roughly 15 mA, so a 100 nF decoupling capacitor with an ESR below 100 mOhm keeps supply ripple below 10 mV.
Route the crystal or resonator as close as possible to XTAL1/XTAL2 (pins 12 and 13) with short, symmetric traces and guard them with ground. Keep the ISP header (MOSI, MISO, SCK, RESET) traces away from the ADC input pins to avoid digital coupling into analog measurements. Place the 32-TQFP thermal and ground pins on a solid ground plane to minimize return-path inductance.
Do not leave the RESET pin floating; use a 10 kOhm pull-up to VCC and a 100 nF capacitor to ground for reliable power-on reset. If the internal RC oscillator is used as the system clock, calibrate it via the OSCCAL register because its factory tolerance is several percent. Also verify that the 16 MHz speed grade is only valid from 4.5 V to 5.5 V; at 3.3 V the safe maximum is about 8 MHz per the Microchip ATmega8 datasheet.
Compliance Information
Distributor listings (DigiKey, Mouser, LCSC) indicate RoHS compliance for the ATMEGA8-16AI. AEC-Q100 qualification is not applicable to this commercial/industrial grade part. Halogen-free status is not stated in the provided data.
