ATMEGA128A-AUR - 8-Bit AVR MCU 128KB Flash 16MHz TQFP-64 | Microchip
MPN: ATMEGA128A-AUR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.2 | $5.20 |
| 10 | $4.68 | $46.80 |
| 100 | $4.16 | $416.00 |
| 500 | $3.64 | $1,820.00 |
| 1,000 | $3.12 | $3,120.00 |
ATMEGA128A-AUR Overview
An 8-bit microcontroller (MCU) is a self-contained computing device that integrates a processor core, memory, and programmable peripherals on a single silicon die. The ATmega128A belongs to the AVR family of microcontrollers, positioned within the broader hierarchy of embedded processors under the power-management and control-system category. AVR MCUs execute powerful instructions in a single clock cycle, achieving throughputs approaching 1 MIPS per MHz, allowing system designers to optimize power consumption versus processing speed.
Key features include an advanced RISC architecture with 133 powerful instructions, most of which execute in a single clock cycle; 32 general-purpose working registers; four flexible timer/counters with compare modes and PWM channels; two USARTs for serial communication; and a byte-oriented two-wire serial interface (TWI/I2C) plus SPI. The 16MHz maximum clock frequency delivers approximately 16 MIPS of throughput at 5V operation.
The device operates from a single supply of 2.7V to 5.5V, supporting both 3.3V and 5V system designs. Flash memory supports in-system programming (ISP) through the SPI port, enabling firmware updates after board assembly without removing the device. Read-while-write flash capability allows firmware execution during EEPROM or flash programming operations.
Typical applications include industrial control and factory automation, sensor and data-acquisition systems, motor and power-control nodes, building automation, and legacy embedded designs where a mature, well-documented AVR platform with ample flash is required. The 53 I/O lines and external memory interface make it well suited to designs driving keypads, displays, and multiple serial links simultaneously.
For design, note that flash programming voltage and bootloader considerations affect layout: reserve access to the SPI pins (PB0-PB3) for ISP programming headers. Decouple VCC pins with 100nF ceramics placed close to each supply pin.
This page synthesizes distributor pricing, drop-in alternatives, pinout data, and practical design notes not found in the manufacturer datasheet, providing a single reference for sourcing and design decisions.
Drop-in alternatives for ATMEGA128A-AUR — 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 ATMEGA128A-AUR (same form factor and footprint) — differing in Package, SRAM, Supply Voltage Range, Flash Memory, Timers/Counters.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA128-16AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$14.3 / Unit
View Datasheet →ATMEGA128A-AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$4.3 / Unit
View Datasheet →ATMEGA128-16MUR
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$8.4 / Unit
View Datasheet →ATMEGA1284-AUR
✅ Drop-In✓ In Stock
$4.61 / Unit
View Datasheet →ATMEGA1284P-MUR
✅ Drop-In✓ In Stock
Contact for price
View Datasheet →ATMEGA1281V-8AUR
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$4.4 / Unit
View Datasheet →ATMEGA128A-AUR Maximum Ratings & Electrical Characteristics
| Core Architecture | AVR 8-bit RISC |
| Flash Memory | 128KB (64K x 16) In-System Programmable |
| EEPROM | 4KB |
| SRAM | 4KB |
| Maximum Clock Frequency | 16 MHz |
| Supply Voltage Range | 2.7 V to 5.5 V |
| I/O Lines | 53 |
| Working Registers | 32 general purpose |
| Instruction Set | 133 powerful instructions, most single-cycle |
| Timers/Counters | 4 flexible timer/counters with compare modes and PWM |
| USARTs | 2 |
| Serial Interfaces | TWI (I2C), SPI, 2x USART |
| Package | 64-TQFP (14x14 mm) |
| Mounting Type | Surface Mount |
| Real-Time Counter | Yes |
ATMEGA128A-AUR Pin Configuration
| Pin 1 | PE0 — Port E bit 0 / RXD0 (USART0 receive) |
| Pin 2 | PE1 — Port E bit 1 / TXD0 (USART0 transmit) |
| Pin 3 | PE2 — Port E bit 2 / XCK0 / AIN0 |
| Pin 4 | PE3 — Port E bit 3 / OC3A / AIN1 |
| Pin 5 | PE4 — Port E bit 4 / OC3B / INT4 |
| Pin 6 | PE5 — Port E bit 5 / OC3C / INT5 |
| Pin 7 | PE6 — Port E bit 6 / T3 / INT6 |
| Pin 8 | PE7 — Port E bit 7 / ICP3 / INT7 |
| Pin 9 | GND — Ground |
| Pin 10 | VCC — Digital supply voltage |
| Pin 11 | PB0 — Port B bit 0 / SS (SPI slave select) |
| Pin 12 | PB1 — Port B bit 1 / SCK (SPI clock) |
| Pin 13 | PB2 — Port B bit 2 / MOSI |
| Pin 14 | PB3 — Port B bit 3 / MISO |
| Pin 15 | PB4 — Port B bit 4 / OC0 / OC2 (PWM) |
| Pin 16 | PB5 — Port B bit 5 / OC1A (PWM) |
| Pin 17 | PB6 — Port B bit 6 / OC1B (PWM) |
| Pin 18 | PB7 — Port B bit 7 / OC2 / OC1C (PWM) |
| Pin 19 | PF0 — Port F bit 0 / ADC0 |
| Pin 20 | RESET — Reset input (active low) |
| Pin 21 | PF1 — Port F bit 1 / ADC1 |
| Pin 22 | PF2 — Port F bit 2 / ADC2 |
| Pin 23 | PF3 — Port F bit 3 / ADC3 |
| Pin 24 | PF4 — Port F bit 4 / ADC4 / TCK (JTAG) |
| Pin 25 | PF5 — Port F bit 5 / ADC5 / TMS (JTAG) |
| Pin 26 | PF6 — Port F bit 6 / ADC6 / TDO (JTAG) |
| Pin 27 | PF7 — Port F bit 7 / ADC7 / TDI (JTAG) |
| Pin 28 | AREF — Analog reference voltage for ADC |
| Pin 29 | GND — Ground |
| Pin 30 | AVCC — Analog supply voltage for ADC |
| Pin 31 | PA0 — Port A bit 0 / ADC0 / external memory address/data line A0/D0 |
| Pin 32 | PA1 — Port A bit 1 / ADC1 / external memory A1/D1 |
| Pin 33 | PA2 — Port A bit 2 / ADC2 / external memory A2/D2 |
| Pin 34 | PA3 — Port A bit 3 / ADC3 / external memory A3/D3 |
| Pin 35 | PA4 — Port A bit 4 / ADC4 / external memory A4/D4 |
| Pin 36 | PA5 — Port A bit 5 / ADC5 / external memory A5/D5 |
| Pin 37 | PA6 — Port A bit 6 / ADC6 / external memory A6/D6 |
| Pin 38 | PA7 — Port A bit 7 / ADC7 / external memory A7/D7 |
| Pin 39 | PC0 — Port C bit 0 / external memory address line A8 |
| Pin 40 | PC1 — Port C bit 1 / external memory address line A9 |
| Pin 41 | PC2 — Port C bit 2 / external memory address line A10 |
| Pin 42 | PC3 — Port C bit 3 / external memory address line A11 |
| Pin 43 | PC4 — Port C bit 4 / external memory address line A12 |
| Pin 44 | PC5 — Port C bit 5 / external memory address line A13 |
| Pin 45 | PC6 — Port C bit 6 / external memory address line A14 |
| Pin 46 | PC7 — Port C bit 7 / external memory address line A15 |
| Pin 47 | GND — Ground |
| Pin 48 | VCC — Digital supply voltage |
| Pin 49 | PD0 — Port D bit 0 / SCL (TWI) / INT0 |
| Pin 50 | PD1 — Port D bit 1 / SDA (TWI) / INT1 |
| Pin 51 | PD2 — Port D bit 2 / RXD1 (USART1) / INT2 |
| Pin 52 | PD3 — Port D bit 3 / TXD1 (USART1) / INT3 |
| Pin 53 | PD4 — Port D bit 4 / ICP1 (input capture) |
| Pin 54 | PD5 — Port D bit 5 / XCK1 |
| Pin 55 | PD6 — Port D bit 6 / T1 (timer 1 external clock) |
| Pin 56 | PD7 — Port D bit 7 / T2 (timer 2 external clock) |
| Pin 57 | PG0 — Port G bit 0 / WR (external memory write strobe) |
| Pin 58 | PG1 — Port G bit 1 / RD (external memory read strobe) |
| Pin 59 | PG2 — Port G bit 2 / ALE (external memory address latch enable) |
| Pin 60 | XTAL1 — Crystal/oscillator input |
| Pin 61 | XTAL2 — Crystal/oscillator output |
| Pin 62 | PG3 — Port G bit 3 / TOSC2 (RTC crystal output) |
| Pin 63 | PG4 — Port G bit 4 / TOSC1 (RTC crystal input) |
| Pin 64 | VCC — Digital supply voltage |
Typical Applications
ATMEGA128A-AUR is suitable for 6 applications: Industrial Control and Factory Automation, Building Automation and HVAC Controllers, Data Acquisition and Sensor Systems, Legacy Design Continuation and Board Spins, Motor Control and Power Electronics Supervision, Embedded Communication and Gateway Nodes.
Industrial Control and Factory Automation
The ATMEGA128A-AUR suits industrial control nodes because its 53 general-purpose I/O lines, four timer/counters with PWM, and two USARTs can simultaneously drive relays, read limit switches, and communicate with SCADA gateways over RS-485 (via USART). Operating from 2.7V to 5.5V with industrial temperature rating, it tolerates noisy factory power rails. Its 128KB flash with bootloader section supports field firmware updates on deployed machinery without removing the device from the PCB. In a typical PLC expansion module, the 16MHz core executes control loops approaching 16 MIPS, sufficient for sequential control and monitoring tasks, while the external memory interface allows expansion when logging requires more RAM than the internal 4KB SRAM provides.
Recommended
Building Automation and HVAC Controllers
Building automation panels need many I/O, multiple serial buses, and low unit cost - the ATMEGA128A-AUR delivers all three. Its byte-oriented TWI (I2C) interface connects environmental sensors (temperature, humidity, CO2), while the two USARTs handle BACnet/Modbus front ends and an RS-485 trunk. The 4KB EEPROM retains setpoints and schedules through power outages, and the real-time counter supports time-of-day scheduling with a 32.768kHz watch crystal on the TOSC pins. The 2.7-5.5V supply range allows a single 5V rail derived from mains power. The 128KB flash comfortably hosts protocol stacks plus a bootloader for remote firmware updates over the building network.
Recommended
Data Acquisition and Sensor Systems
For multi-channel data acquisition, the ATMEGA128A-AUR's port PA doubles as the ADC input multiplex while port PC serves the external memory bus, letting one chip manage eight analog channels and parallel ADCs or external SRAM simultaneously. The four timer/counters generate precise sampling clocks and PWM excitation signals for sensor bridges. With throughput near 1 MIPS per MHz at 16MHz, DSP-light tasks such as filtering and scaling complete in real time. The industrial temperature range suits unconditioned field enclosures, and the two USARTs stream results to a host or radio module. The 2.7V floor supports 3.3V-only designs where the ADC reference and sensor front ends run at lower rails.
Recommended
Legacy Design Continuation and Board Spins
Many PCBs designed around the ATmega103 or original ATmega128 remain in production, and the ATMEGA128A-AUR is the sanctioned continuation path: Microchip documents that the ATmega128A is 100% pin compatible with the ATmega103 and directly replaces it on current printed circuit boards, and it shares the ATmega128's 64-TQFP footprint and peripheral map. Engineers refreshing EOL assemblies can drop in the ATmega128A-AUR without layout changes, revalidating only firmware errata items. Keeping the SPI ISP header on these boards preserves in-field reprogramming, and the active lifecycle status ensures long-term supply compared with sourcing older, allocation-prone dies.
Recommended
Motor Control and Power Electronics Supervision
The ATMEGA128A-AUR supervises small motor drives and power stages using its four timer/counters: two 8-bit and 16-bit timers provide complementary PWM channels with compare modes for DC motor speed control and servo positioning. The external interrupt pins (INT0-INT7 across ports D and E) capture quadrature encoder or zero-cross signals, while USART connectivity reports status to a higher-level controller. The 5V-tolerant industrial part drives MOSFET gate-driver ICs directly through its PWM outputs with appropriate buffering. Its deterministic single-cycle RISC execution keeps current-loop timing jitter low, and the 4KB EEPROM stores calibration constants such as offset, gain, and thermal limits across power cycles.
Recommended
Embedded Communication and Gateway Nodes
With two independent USARTs plus SPI plus TWI, the ATMEGA128A-AUR bridges dissimilar buses in compact gateway nodes - for example, translating Modbus RTU on RS-485 to a proprietary SPI radio link, or buffering sensor data from a TWI sensor cluster to a cellular modem. The 128KB flash hosts protocol stacks, buffers, and a boot loader for remote updates delivered over either UART. At 16MHz the core sustains sustained serial throughput at 115200 baud on both UARTs with headroom for framing and CRC computation. The 53 I/O lines handle DIP-switch address selection, status LEDs, and flow-control handshakes, consolidating gateway logic into a single low-cost MCU.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA128A-AUR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA128-16AU | ATMEGA128A-AU | ATMEGA1284-AUR | ATMEGA1281V-8AUR |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 64-TQFP (14x14 mm) | 64-TQFP - same | 64-TQFP - same | 64-TQFP - same | 64-TQFP - same |
| Flash Memory | 128KB | 128KB | 128KB | 128KB | 128KB |
| SRAM | 4KB | 4KB | 4KB | 16KB | 8KB |
| Max Clock Frequency | 16 MHz | 16 MHz | 16 MHz | 20 MHz | 8 MHz |
| Supply Voltage | 2.7 V to 5.5 V | 4.5 V to 5.5 V (16MHz grade) | 2.7 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V |
| Lifecycle Status | Active | Not recommended for new designs (superseded) | Active | Active | Active |
Key Differentiators
- Active lifecycle continuation of the ATmega128 legacy core (vs ATMEGA128-16AU)
- 100% pin compatibility with ATmega103 for board revivals (vs ATMEGA1284-AUR)
- 53 I/O lines with external memory interface (vs ATMEGA1281V-8AUR)
Design Notes
The ATMEGA128A-AUR requires supply decoupling on every VCC pin (10, 48, 64) - fit a 100nF ceramic within 5mm of each pin, plus one bulk 10uF per board. At 5V and 16MHz, active-mode current is in the tens of milliamp range (exact figure: consult the Microchip datasheet current-consumption tables). When running below 4.5V, derate the maximum clock frequency per the AVR frequency-versus-voltage curve to avoid illegal timing; a 3.3V design should target 8MHz crystals unless the datasheet curve confirms a higher safe speed.
Reserve the SPI pins (PB0-PB3, pins 11-14) for an in-circuit ISP programming header - a 6-pin or 10-pin AVR ISP layout. Ensure series resistors isolate the ISP header from peripheral loads on SCK/MOSI/MISO so programming is not disturbed during operation. Keep the XTAL1/XTAL2 crystal (pins 60-61) traces short and guard them with ground pour; the ATmega128A also supports the TOSC 32.768kHz crystal on PG3/PG4 (pins 62-63) for the real-time counter - route it away from the main crystal to prevent coupling.
Migrating from ATmega103 or original ATmega128: the ATmega128A is pin-compatible, but fuse defaults, JTAG enable state (JTAG shares PF4-PF7, pins 24-27), and certain peripheral errata differ. If PF4-PF7 are needed as ADC inputs, disable JTAG via fuse in software sequence or at programming time. Also note RESET (pin 20) must not be pulled above VCC; a 10k pull-up plus optional reset supervisor improves noise immunity in industrial environments. Verify bootloader fuse (BOOTRST) settings before field deployment.
When the external memory interface is used, ports PA (pins 31-38) and PC (pins 39-46) switch the heaviest loads; keep these bus traces under 100mm and add 22-33 ohm series resistors on ALE (PG2, pin 59), WR (PG0, pin 57), and RD (PG1, pin 58) to control ringing. Ground return paths for the bus should reference pin 47 GND, which sits directly adjacent to port PC on this pinout, minimizing loop area for address/data switching noise.
Compliance Information
Distributor listings (DigiKey/Mouser) present the ATMEGA128A-AUR as a current RoHS-compliant, lead-free industrial MCU. REACH and halogen-free status require confirmation from Microchip's material declaration documents.