ATMEGA8A-PN - AVR 8-bit MCU 16MHz 8KB Flash | Microchip
MPN: ATMEGA8A-PN ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.56 | $3.56 |
| 10 | $3.25 | $32.50 |
| 100 | $2.95 | $295.00 |
| 500 | $2.7 | $1,350.00 |
| 1,000 | $2.45 | $2,450.00 |
ATMEGA8A-PN Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a processor core, program memory, data memory, and peripherals on one die. The ATmega family is built on the AVR enhanced RISC architecture, which executes most instructions in a single clock cycle, achieving throughput close to 1 MIPS per MHz. This makes it a member of the broader hierarchy: MCU -> embedded microcontroller -> integrated circuit -> semiconductor.
Key features include 8KB of self-programmable Flash with Read-While-Write support, three flexible Timer/Counters with compare modes, a hardware serial programmable USART, I2C (TWI) and SPI interfaces for connectivity, internal and external interrupt sources, and a 6-channel 10-bit ADC. Operating voltage spans 2.7V to 5.5V, and the PN suffix denotes the industrial temperature grade of -40C to +105C per distributor listings, giving headroom above the typical industrial spec.
Architecturally, the AVR core provides 32 general-purpose working registers directly connected to the ALU, allowing two independent registers to be accessed in one instruction executed in one cycle. This single-cycle execution model is the reason AVR parts deliver near-linear MIPS-per-MHz efficiency compared with older 8051-class cores that need 6 to 12 cycles per instruction.
Typical applications include hobbyist and educational boards (it is the classic Arduino-compatible target), small appliance and industrial control panels, sensor nodes reading analog inputs through its 10-bit ADC, and low-cost motor or relay control using the timer PWM outputs.
Design consideration: because the PDIP package is through-hole, keep crystal traces short and decouple VCC/AVCC pins with 100nF ceramics; also note that migrating firmware to an ATmega88-class pin-compatible part requires interrupt vector remapping per Microchip application note AVR094.
This page adds value beyond the datasheet by synthesizing distributor pricing history, pin-compatible ATmega alternatives, drop-in replacement guidance, and practical design notes in one citable reference.
Drop-in alternatives for ATMEGA8A-PN — 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 ATMEGA8A-PN (same form factor and footprint) — differing in Timers, ADC, Operating Voltage Range, Mounting Type, Package.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA8-16PI
✅ Drop-In✓ In Stock
$1.85 / Unit
View Datasheet →ATMEGA88PA-PN
✅ Drop-In✓ In Stock
$2.02 / Unit
View Datasheet →ATMEGA88-20PI
✅ Drop-In✓ In Stock
$1.85 / Unit
View Datasheet →ATMEGA88V-10PU
✅ Drop-In✓ In Stock
$1.3 / Unit
View Datasheet →ATMEGA88A-PU
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
ATMEGA8A-PN Maximum Ratings & Electrical Characteristics
| Core Processor | AVR |
| Core Size | 8-Bit |
| Architecture | AVR enhanced RISC |
| Maximum Clock Speed | 16 MHz |
| Program Memory (Flash) | 8 KB (4K x 16) |
| EEPROM | 512 B |
| SRAM | 1 KB (1K x 8) |
| Number of I/O | 23 |
| Operating Voltage Range | 2.7 V to 5.5 V |
| Connectivity | I2C (TWI), SPI, UART/USART |
| ADC Resolution | 10-bit |
| Timers | 3 Timer/Counters with compare modes |
| Package / Case | 28-DIP (0.300 in, 7.62 mm) |
| Mounting Type | Through Hole |
| Operating Temperature | -40C to +105C |
| MIPS per MHz | up to 1 (approx.) |
| Product Status | Active |
ATMEGA8A-PN Pin Configuration
| Pin 1 | PC6 (RESET) — Reset input (active low) |
| Pin 2 | PD0 (RXD) — Port D bit 0 / USART receive |
| Pin 3 | PD1 (TXD) — Port D bit 1 / USART transmit |
| Pin 4 | PD2 (INT0) — Port D bit 2 / external interrupt 0 |
| Pin 5 | PD3 (INT1) — Port D bit 3 / external interrupt 1 |
| Pin 6 | PD4 (T0) — Port D bit 4 / Timer0 external clock |
| Pin 7 | VCC — Digital supply voltage |
| Pin 8 | GND — Ground |
| Pin 9 | PB6 (XTAL1/TOSC1) — Port B bit 6 / crystal oscillator input |
| Pin 10 | PB7 (XTAL2/TOSC2) — Port B bit 7 / crystal oscillator output |
| Pin 11 | PD5 (T1) — Port D bit 5 / Timer1 external clock |
| Pin 12 | PD6 (AIN0) — Port D bit 6 / analog comparator positive input |
| Pin 13 | PD7 (AIN1) — Port D bit 7 / analog comparator negative input |
| Pin 14 | PB0 (ICP1) — Port B bit 0 / Timer1 input capture |
| Pin 15 | PB1 (OC1A) — Port B bit 1 / Timer1 PWM output A |
| Pin 16 | PB2 (SS/OC1B) — Port B bit 2 / SPI slave select / Timer1 PWM output B |
| Pin 17 | PB3 (MOSI/OC2) — Port B bit 3 / SPI master out / Timer2 PWM output |
| Pin 18 | PB4 (MISO) — Port B bit 4 / SPI master in |
| Pin 19 | PB5 (SCK) — Port B bit 5 / SPI clock |
| Pin 20 | AVCC — ADC supply voltage |
| Pin 21 | AREF — ADC analog reference |
| Pin 22 | GND — Ground (analog) |
| Pin 23 | PC0 (ADC0) — Port C bit 0 / ADC channel 0 |
| Pin 24 | PC1 (ADC1) — Port C bit 1 / ADC channel 1 |
| Pin 25 | PC2 (ADC2) — Port C bit 2 / ADC channel 2 |
| Pin 26 | PC3 (ADC3) — Port C bit 3 / ADC channel 3 |
| Pin 27 | PC4 (ADC4/SDA) — Port C bit 4 / ADC4 / TWI data |
| Pin 28 | PC5 (ADC5/SCL) — Port C bit 5 / ADC5 / TWI clock |
Typical Applications
ATMEGA8A-PN is suitable for 6 applications: Hobbyist and Educational Boards, Industrial Control Panels, Sensor Nodes and Data Loggers, Motor and Relay Control, Home Automation and IoT Peripherals, Test Fixtures and Legacy Equipment Repair.
Hobbyist and Educational Boards
ATMEGA8A-PN is the classic through-hole target for Arduino-compatible and educational microcontroller boards. Its 16MHz AVR core delivers about 1 MIPS per MHz, and the 28-pin PDIP package is socketed and hand-solderable, so students can swap chips without hot-air tools. The 8KB Flash is enough for bootloader plus modest sketches controlling LEDs, buttons, and serial terminals via the hardware USART. Its 10-bit ADC lets beginners read potentiometers and sensors directly. Performance consideration: modern Arduino core libraries consume several KB, so keep sketches lean or move to a pin-compatible ATMEGA328P when code exceeds roughly 6KB. Bootloader flashing requires an ISP programmer such as USBasp on the MOSI/MISO/SCK pins PB3-PB5.
Recommended
Industrial Control Panels
In industrial control panels, ATMEGA8A-PN drives relays, reads limit switches, and supervises simple processes at low cost. The -40C to +105C PN industrial temperature grade exceeds typical factory ambient requirements, and the 5.5V maximum supply matches standard 5V logic rails derived from 24V industrial supplies via a small buck or linear regulator. Its three timers with compare modes generate PWM for heater or fan control, while the external interrupt pins INT0/INT1 capture switch inputs. Use optocoupler isolation on all field wiring and a watchdog timer (available on-chip) to recover from upsets. The 23 I/O lines cover panel button matrices and status LEDs without port expanders in most small panels.
Recommended
Sensor Nodes and Data Loggers
For low-cost sensor nodes, ATMEGA8A-PN combines a 6-channel 10-bit ADC with 512B EEPROM, enabling calibration constants and small logs to persist across power cycles without external memory. The I2C (TWI) and SPI interfaces connect temperature, pressure, or humidity sensors, and the USART streams readings to a GSM/Wi-Fi module or PC. At 2.7V operation it runs directly from a lithium coin cell or two AA cells, though maximum clock must be derated at low voltage per the datasheet frequency-voltage curve. Performance consideration: 1KB SRAM limits buffering to small sample windows; store raw data to EEPROM in 512B pages or stream continuously. Sleep modes cut consumption to microamps between samples.
Recommended
Motor and Relay Control
ATMEGA8A-PN suits small motor and actuator control thanks to its Timer/Counter PWM outputs (OC1A on PB1, OC1B on PB2, OC2 on PB3) and 23 GPIO for direction and enable lines. The 16MHz clock gives 8-bit PWM resolution up to roughly 15.6kHz with Timer1 in fast PWM mode, above audible range for fan and pump control. Hardware dead-time must be implemented in software for H-bridges, so keep switching frequency moderate. The 10-bit ADC reads current shunts or potentiometer speed commands for closed-loop control. Drive external MOSFET gate drivers rather than the GPIO directly, since port pin current is limited, and always freewheel inductive loads with flyback diodes to protect the MCU pins.
Recommended
Home Automation and IoT Peripherals
ATMEGA8A-PN acts as an inexpensive node controller in home automation systems, handling keypad scanning, relay outputs, and serial links to a central hub. The hardware USART at 16MHz supports reliable 115200 baud communication with ESP or RS-485 transceiver modules for wired multi-drop networks, and the TWI interface chains multiple ATmega nodes or sensors on two shared lines. The internal RC oscillator option frees the XTAL pins for I/O in cost-sensitive nodes, at reduced clock accuracy. Performance consideration: with no native radio, wireless connectivity must be delegated to a companion module; budget the 1KB SRAM carefully when parsing received frames, using fixed-length buffers to avoid stack overflow in 8KB-Flash-class designs.
Recommended
Test Fixtures and Legacy Equipment Repair
Because ATMEGA8A-PN is socketed through-hole and still in active production, it is a standard replacement CPU for legacy equipment repair and bench test fixtures. Equipment originally designed around ATmega8 or even older parts can be reworked by dropping an ATmega8A into the same 28-pin socket with binary-compatible firmware; Microchip positions the ATmega8A as the direct successor die. In custom test fixtures, its timers generate precise stimulus frequencies and the ADC captures analog responses, while the SPI port dumps results to a PC. Keep spare chips pre-programmed with fixture firmware to minimize downtime. Verify fuse bits (clock source, brown-out) match the original socketed part after replacement.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA8A-PN — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA8-16PI | ATMEGA88PA-PN | ATMEGA88-20PI | ATMEGA88V-10PU | ATMEGA88A-PU |
|---|---|---|---|---|---|---|
| Package | 28-DIP (0.300 in) | 28-DIP (0.300 in) - same | 28-DIP (0.300 in) - same | 28-DIP (0.300 in) - same | 28-DIP (0.300 in) - same | 28-DIP (0.300 in) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Max Clock Speed | 16 MHz | 16 MHz | 20 MHz | 20 MHz | 10 MHz | 20 MHz |
| Flash | 8 KB | 8 KB | 8 KB | 8 KB | 8 KB | 8 KB |
| SRAM | 1 KB | 1 KB | 1 KB | 1 KB | 1 KB | 1 KB |
| Operating Voltage | 2.7 V to 5.5 V | 4.5 V to 5.5 V (16MHz grade) | 1.8 V to 5.5 V | 4.5 V to 5.5 V | 1.8 V to 5.5 V | 2.7 V to 5.5 V |
| Firmware Compatibility with ATmega8 | Native (same family) | Binary compatible | Port required (AVR094) | Port required (AVR094) | Port required (AVR094) | Port required (AVR094) |
| Temperature Grade | -40C to +105C (per distributor) | -40C to +85C (I grade) | -40C to +85C (I grade) | -40C to +85C (I grade) | -40C to +85C (I grade) | -40C to +85C (I grade) |
Key Differentiators
- Through-hole PDIP package (vs ATMEGA8A-MUR (VQFN surface-mount sibling))
- 105C industrial temperature grade (vs ATMEGA8-16PI)
- Native ATmega8 firmware compatibility (vs ATMEGA88PA-PN)
- Cost floor for small code (vs ATMEGA328P (32KB Flash, 28-DIP))
Design Notes
On a PDIP through-hole layout, place 100nF ceramic decoupling capacitors directly across VCC (pin 7)-GND (pin 8) and AVCC (pin 20)-GND (pin 22), with traces under 10mm. Tie AVCC to VCC through a 10uH ferrite or 100-ohm resistor when the ADC is used, and decouple AREF (pin 21) with 100nF to GND only - never place a capacitor directly from AREF to a reference voltage source. Keep the 16MHz crystal within 15mm of pins 9-10 with 22pF load capacitors per crystal specification.
The 2.7V-5.5V supply range interacts with maximum frequency: the full 16MHz rating applies at 4.5V-5.5V. Estimated: for a 3.3V design, derate maximum safe clock to approximately 13.5MHz per the AVR frequency-vs-voltage curve, or use the internal 8MHz RC oscillator. Estimated current draw is on the order of a few mA active at 16MHz/5V, dropping to microamps in power-down sleep - size the regulator for active current plus all driven loads on the 23 I/O pins (40mA absolute max per pin, per datasheet limits).
Two pitfalls dominate ATmega8A projects. First, migrating to ATmega88-class pin-compatible parts silently breaks firmware: interrupt vectors relocate and register names change (Microchip app note AVR094 documents every change) - recompile and re-test rather than re-flashing the old binary. Second, forget to set fuse bits and the chip may run on the 1MHz internal RC instead of the external 16MHz crystal; after ISP programming, verify low fuse for the external crystal setting and enable brown-out detection (BOD) for supply-glitch robustness in industrial environments.
Compliance Information
RoHS/lead-free status per Microchip policy for active ATmega parts as listed by distributors; REACH, halogen-free, and conflict-minerals declarations not found in the provided data - verify via Microchip compliance portal.
