ATMEGA8-16PI - 8KB Flash, 16MHz AVR MCU, 28-PDIP | Microchip
MPN: ATMEGA8-16PI β End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.2 | $3.20 |
| 10 | $2.85 | $28.50 |
| 100 | $2.45 | $245.00 |
| 500 | $2.1 | $1,050.00 |
| 1,000 | $1.85 | $1,850.00 |
ATMEGA8-16PI Overview
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, delivering throughput near 1 MIPS per MHz. Microcontrollers of this class integrate program Flash, SRAM, EEPROM, peripherals, and a CPU core in one package, sitting between simple logic ICs and application processors in the embedded systems hierarchy.
Key features include 8KB self-programmable Flash with 10,000 write-cycle endurance, 23 programmable I/O lines, one 8-channel 10-bit ADC (6 channels in PDIP), two 8-bit and one 16-bit timer with PWM, a hardware USART, SPI, and TWI (I2C) interfaces, plus an on-chip analog comparator. These peripherals allow the ATMEGA8-16PI to replace multiple discrete components in compact embedded designs.
The AVR core uses Harvard architecture with separate program and data buses, and includes 32 general-purpose working registers directly connected to the ALU, enabling single-cycle execution and high code density. In-system programmability via SPI allows firmware updates without removing the device from the board, supported by lock bits for code protection.
Typical applications include hobby and Arduino-compatible boards, industrial control panels, appliance control, sensor interfacing with the built-in ADC, and low-cost serial communication bridges using the hardware USART. The DIP package is favored for prototyping, education, and repair of legacy through-hole designs.
Design-wise, the 4.5V to 5.5V operating range pairs naturally with 5V logic; for 2.7V to 5.5V or low-power battery designs, select the ATmega8L speed-graded variant instead. Add 0.1uF decoupling on VCC and AVCC, and keep the reset pin pulled up for reliable ISP programming.
This page synthesizes verified distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, with data verified as of 2026-09-18.
Drop-in alternatives for ATMEGA8-16PI 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 ATMEGA8-16PI (same form factor and footprint) β differing in ADC Channels, ADC Resolution, Mounting Type, Timers.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA8A-PU
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA8-16PU
β Drop-Inβ In Stock
$2.05 / Unit
View Datasheet βATMEGA8-16PC
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA8A-PI
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA48-20PI
β Drop-Inβ In Stock
$0.98 / Unit
View Datasheet βATMEGA8-16PI Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Maximum Clock Frequency | 16 MHz |
| Program Memory Size | 8 KB (4K x 16) Flash |
| Program Memory Type | In-System Programmable Flash |
| SRAM Size | 1 KB |
| EEPROM Size | 512 B |
| Operating Voltage Range | 4.5 V to 5.5 V |
| Number of I/O Lines | 23 |
| ADC Resolution | 10-bit |
| ADC Channels | 6 (in PDIP package) |
| Timers | 2 x 8-bit, 1 x 16-bit |
| Communication Interfaces | USART, SPI, TWI (I2C) |
| Operating Temperature Range | -40C to +85C (industrial) |
| Package | 28-PDIP (0.300 in, 7.62 mm) |
| Mounting Type | Through-Hole |
| MIPS Rating | Up to 16 MIPS (approx. 1 MIPS/MHz) |
| Brand / Manufacturer | Atmel (now Microchip Technology) |
ATMEGA8-16PI Pin Configuration
| Pin 1 | PC6 (RESET) β Reset input / Port C bit 6 |
| Pin 2 | PD0 (RXD) β Port D bit 0 / USART receive |
| Pin 3 | PD1 (TXD) β Port D bit 1 / USART transmit |
| Pin 4 | PD2 (INT0) β Port D bit 2 / External interrupt 0 |
| Pin 5 | PD3 (INT1) β Port D bit 3 / External interrupt 1 |
| Pin 6 | PD4 (T0/XCK) β Port D bit 4 / Timer0 counter input |
| Pin 7 | VCC β Digital supply voltage |
| Pin 8 | GND β Ground |
| Pin 9 | PB6 (XTAL1/TOSC1) β Crystal oscillator input / Timer oscillator |
| Pin 10 | PB7 (XTAL2/TOSC2) β Crystal oscillator output / Timer oscillator |
| Pin 11 | PD5 (T1/OC1B) β Port D bit 5 / Timer1 counter input |
| Pin 12 | PD6 (AIN0) β Port D bit 6 / Analog comparator positive input |
| Pin 13 | PD7 (AIN1) β Port D bit 7 / Analog comparator negative input |
| Pin 14 | PB0 (ICP1) β Port B bit 0 / Timer1 input capture |
| Pin 15 | PB1 (OC1A) β Port B bit 1 / Timer1 output compare A (PWM) |
| Pin 16 | PB2 (SS/OC1B) β Port B bit 2 / SPI slave select, Timer1 output compare B |
| Pin 17 | PB3 (MOSI/OC2) β Port B bit 3 / SPI master output, Timer2 PWM output |
| Pin 18 | PB4 (MISO) β Port B bit 4 / SPI master input |
| Pin 19 | PB5 (SCK) β Port B bit 5 / SPI clock |
| Pin 20 | AVCC β ADC supply voltage |
| Pin 21 | AREF β ADC analog reference input |
| Pin 22 | GND β Ground |
| Pin 23 | PC0 (ADC0) β Port C bit 0 / ADC channel 0 |
| Pin 24 | PC1 (ADC1) β Port C bit 1 / ADC channel 1 |
| Pin 25 | PC2 (ADC2) β Port C bit 2 / ADC channel 2 |
| Pin 26 | PC3 (ADC3) β Port C bit 3 / ADC channel 3 |
| Pin 27 | PC4 (ADC4/SDA) β Port C bit 4 / ADC channel 4 / TWI data |
| Pin 28 | PC5 (ADC5/SCL) β Port C bit 5 / ADC channel 5 / TWI clock |
Typical Applications
ATMEGA8-16PI is suitable for 6 applications: Arduino-Compatible Hobby Boards, Industrial Control Panels, Appliance and Consumer Product Control, Sensor Data Acquisition Nodes, Serial Communication Bridges, Legacy Board Repair and Service.
Arduino-Compatible Hobby Boards
The ATMEGA8-16PI powered early Arduino boards (the 2005-era Arduino NG) and remains popular for retro-compatible hobby builds. Its SPI in-system programming allows bootloader flashing directly on the board with a USBasp or Arduino-as-ISP setup, requiring only PB3/PB4/PB5 (MOSI/MISO/SCK) plus RESET routed to a 6-pin ISP header. With 16MHz crystal and 22pF capacitors on XTAL1/XTAL2, the chip delivers 16 MIPS for typical sketch workloads, while the 8KB Flash bounds sketches to roughly 7KB after bootloader overhead. The 28-PDIP through-hole package sockets directly, making chip swaps and breadboard prototyping trivial. For new hobby designs, consider the ATmega8A-PU or ATmega328P for active lifecycle support.
Recommended
Industrial Control Panels
The industrial temperature rating of -40C to +85C makes the ATMEGA8-16PI suitable for factory-floor control panels, motor start sequencers, and machine-state monitoring where ambient conditions vary widely. Operating at 5V gives robust noise margins against industrial EMI, and the 10-bit ADC (6 channels on PDIP) digitizes potentiometers, 4-20mA-conditioned sensor signals, or thermistor dividers with 10-bit resolution. Hardware timers generate PWM for heater or fan control while the USART links to RS-485 transceivers for Modbus-style networking. The 28-PDIP socketed format simplifies field firmware updates via SPI ISP. Note the part is EOL; plan ATMEGA8A-PU substitution for new industrial builds to ensure supply continuity.
Recommended
Appliance and Consumer Product Control
Home appliances such as coffee machines, fans, and small heaters use ATmega8-class MCUs for keypad scanning, relay drive, and LED indication. The ATMEGA8-16PI integrates 23 GPIO lines, enough for a 4x4 keypad matrix, three relay drivers, and indicator LEDs without port expanders, cutting bill-of-materials cost. Its 512B EEPROM stores user settings and calibration data through power cycles with 100,000-cycle endurance. The 16MHz clock executes debounce loops and PWM mixing quickly at low cost, and the watchdog timer adds fault recovery for unattended operation. The 5V-only supply range matches transformer-based appliance power supplies. For new appliance platforms, select the ATmega8A-PU to retain compatibility while gaining active production status.
Recommended
Sensor Data Acquisition Nodes
With a 10-bit successive-approximation ADC offering 6 multiplexed channels in the PDIP variant, plus an internal 2.56V reference option via AREF, the ATMEGA8-16PI serves as a compact multi-channel data acquisition node for temperature, light, and potentiometer arrays. The analog comparator (AIN0/AIN1 on PD6/PD7) provides fast threshold detection without CPU polling, useful for over-limit alarms. Sampled data streams out through the hardware USART to a PC or logger at standard baud rates clocked by a crystal for timing accuracy. Conversions at full ADC clock achieve roughly 15kSPS aggregate throughput, adequate for slow physical-process monitoring. Industrial temperature coverage suits outdoor and unheated enclosures for environmental sensing installations.
Recommended
Serial Communication Bridges
The hardware USART, SPI, and TWI (I2C) peripherals on the ATMEGA8-16PI make it an effective protocol converter between legacy 5V systems and modern peripherals. Typical designs bridge RS-232 equipment to I2C sensors, or translate SPI device streams to UART logging, with 16MHz single-cycle execution comfortably servicing interrupt-driven byte rates up to 115200 baud. TWI hardware handles address generation, ACK, and clock stretching without bit-banging, while the SPI peripheral reaches up to fosc/2 transfer rates for fast flash or display interfacing. Open-drain PB6/PB7 can serve as TOSC pins for a 32.768kHz watch crystal when precision timekeeping is needed alongside conversion tasks, and the industrial rating covers telecom closet environments.
Recommended
Legacy Board Repair and Service
A major ongoing use of ATMEGA8-16PI is repairing equipment designed in the 2000s whose BOM specifies the original ATmega8 DIP microcontroller. The socketed 28-PDIP format allows a technician to extract a failed chip and insert a pre-programmed replacement without soldering. Compatible service parts include ATMEGA8A-PU (active production, firmware-compatible) and ATMEGA8-16PU (same die). When cloning firmware from a donor board, the lock bits may prevent reading; in that case, service organizations hold archive code, or Rochester Electronics supplies authorized pre-programmed units. Always verify fuse settings (clock source, BOD level) when transplanting, as incorrect CKOPT/SUT fuses cause silent startup failures in repaired units.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA8-16PI β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA8A-PU | ATMEGA8-16PU | ATMEGA8-16PC | ATMEGA48-20PI |
|---|---|---|---|---|---|
| Package | 28-PDIP (0.300 in) | 28-PDIP - same footprint | 28-PDIP - same footprint | 28-PDIP - same footprint | 28-PDIP - same footprint |
| Brand | Atmel (Microchip Technology) | Microchip Technology | Atmel (Microchip Technology) | Atmel (Microchip Technology) | Atmel (Microchip Technology) |
| Program Memory (Flash) | 8 KB | 8 KB | 8 KB | 8 KB | 4 KB |
| SRAM | 1 KB | 1 KB | 1 KB | 1 KB | 512 B |
| Max Clock Frequency | 16 MHz | 16 MHz (up to 20 MHz full range) | 16 MHz | 16 MHz | 20 MHz |
| Operating Voltage | 4.5 V to 5.5 V | 4.5 V to 5.5 V (16 MHz grade) | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V |
| Temperature Range | -40C to +85C (industrial) | -40C to +85C | -40C to +85C | 0C to +70C (commercial) | -40C to +85C |
| Lifecycle Status | EOL | Active | EOL | EOL | EOL (ATMEGA48PA-PU active) |
| Firmware Compatibility | Baseline (ATmega8 register map) | Fully compatible | Identical die | Identical die | Different register map - rewrite required |
Key Differentiators
- Industrial temperature grade in same footprint (vs ATMEGA8-16PC)
- Double the memory of the smaller family member (vs ATMEGA48-20PI)
- Socket-friendly through-hole format (vs ATMEGA8-16AI)
Design Notes
Decouple VCC (pin 7) and AVCC (pin 20) each with a 0.1uF ceramic capacitor placed within 5mm of the pins, plus a 10uF bulk capacitor per board. AVCC must be connected to VCC even if the ADC is unused; the datasheet requires AVCC within 0.3V of VCC. Enable brown-out detection (BOD) via fuse at 2.7V or 4.0V so the MCU holds reset during supply dips - critical with EEPROM writes, which corrupt if VCC falls below VCC_MIN during a write cycle.
For through-hole DIP sockets, prefer machine-pin sockets over cheap leaf sockets for reliable long-term contact, especially in vibration-prone industrial settings. Route the crystal (16MHz) with 22pF capacitors directly adjacent to pins 9 and 10 with short returns to GND pin 8; keep the RESET line (pin 1) with a 10k pull-up to VCC and route away from noisy PWM traces. If ISP headers are fitted, add 100 ohm series resistors on SCK/MOSI to avoid loading conflict during normal operation.
Fuse misconfiguration is the top failure mode: selecting external clock when a crystal is fitted, or disabling SPI programming, can brick the chip without a high-voltage parallel programmer. Record factory fuse settings before modification. Also note the internal RC oscillator tolerances (typically +/-2-3% after calibration) are inadequate for precise UART baud rates above 9600 - use a crystal for serial links. Since the original ATmega8 is EOL, validate ATMEGA8A-PU substitutions against the migration document before mass repair orders.
Compliance Information
Compliance attributes were not stated in the provided web data; verify RoHS/lead-free status on the DigiKey or Mouser product page for the exact suffix before ordering, since legacy DIP parts were produced in both leaded and lead-free eras.
