ATMEGA128-16AI - 8-bit AVR MCU 16MHz 128KB Flash | Microchip
MPN: ATMEGA128-16AI β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.5 | $8.50 |
| 10 | $7.75 | $77.50 |
| 100 | $6.9 | $690.00 |
| 500 | $6.35 | $3,175.00 |
| 1,000 | $5.9 | $5,900.00 |
ATMEGA128-16AI Overview
An 8-bit AVR microcontroller is a Harvard-architecture processor that fetches instructions and data over separate buses, allowing most of its 133 powerful instructions to execute in a single clock cycle. Within the product hierarchy, the ATmega128 sits in the ATmega family of flash-based microcontrollers - below the ATmega1280/1281 mega-AVR devices and above the ATmega64 - and functions as a complete embedded system-on-chip integrating CPU, memory, timers, communication peripherals, and an ADC.
Key features include 128KB of self-programmable flash with a boot loader section, dual USARTs, SPI, TWI (I2C), an 8-channel 10-bit ADC, two 8-bit and two 16-bit timers with PWM, and an on-chip JTAG interface for boundary-scan and on-chip debugging. The device operates from 4.5V to 5.5V at 16MHz (per the -16 speed grade), delivering deterministic single-cycle execution without pipelining penalties.
Architecturally, the ATmega128 combines 32 general-purpose working registers directly connected to the ALU, enabling true single-cycle arithmetic in one clock. XMEM interface support expands external memory addressing up to 64KB, useful for data-logging and legacy 8051-style designs migrating to AVR. Power management includes six sleep modes, allowing current consumption optimization from active operation down to microamp levels in power-down.
Typical applications include industrial control and factory automation nodes, legacy ATmega103 PCB upgrades (the ATmega128 is 100% pin compatible with the ATmega103), embedded instrumentation, motor control panels, and building automation controllers where a mature, well-documented 5V MCU simplifies design.
Design consideration: the -16 grade requires 4.5V to 5.5V operation; for 3.3V systems use the 8MHz ATmega128L variant instead, and budget JTAG pin sharing (PF4-PF7) when planning ADC channel allocation.
This page synthesizes distributor pricing context, drop-in alternatives, pin-level design notes, and comparison data not found in a single manufacturer datasheet.
Drop-in alternatives for ATMEGA128-16AI 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 ATMEGA128-16AI (same form factor and footprint) β differing in Timers/Counters, Instructions, Operating Temperature, Package, Core Architecture.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA128-16AU
β Drop-Inβ In Stock
$14.3 / Unit
View Datasheet βATMEGA1281-16MUR
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$8.78 / Unit
View Datasheet βAT90CAN128-16AU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA64-16AI
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA103-16AI
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA128-16AI Maximum Ratings & Electrical Characteristics
| Core Architecture | AVR 8-bit RISC |
| CPU Speed | 16 MHz |
| Flash Memory | 128 KB (64K x 16) In-System Programmable |
| SRAM | 4 KB |
| EEPROM | 4 KB |
| Operating Voltage | 4.5 V to 5.5 V |
| MIPS Throughput | 16 MIPS at 16 MHz |
| ADC | 8-channel 10-bit |
| Timers/Counters | Two 8-bit, Two 16-bit |
| Communication Interfaces | SPI, TWI (I2C), 2x USART |
| JTAG | On-chip JTAG for debugging and boundary scan |
| Instructions | 133 instructions, most single-cycle |
| Package | 64-TQFP (14x14 mm) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C (industrial, per AI suffix) |
| External Memory Interface | XMEM up to 64 KB |
| RoHS Status | unknown |
ATMEGA128-16AI 64-tqfp (14x14 mm) Pin Configuration Guide
Pin configuration for ATMEGA128-16AI (64-tqfp (14x14 mm) package). This digital IC includes GPIO, communication interfaces (UART, SPI, I2C), and power pins. Refer to the manufacturer datasheet for alternate pin functions and configuration options. Essential for embedded system design and PCB layout.
No detailed pinout data available for ATMEGA128-16AI.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA128-16AI is suitable for 6 applications: Industrial Control and Automation, Legacy ATmega103 PCB Upgrade, Embedded Data Logging and Instrumentation, Building Automation Controllers, Motor Control with PWM, Secure Access and Embedded Security Nodes.
Industrial Control and Automation
The ATMEGA128-16AI fits industrial control nodes because its 4.5V-5.5V supply matches legacy 5V industrial I/O standards, providing direct 5V-tolerant inputs for limit switches, encoders, and sensor banks without level translators. In a typical PLC-style node, the two 16-bit timers generate PWM for actuator or motor control while the 8-channel 10-bit ADC samples 0-5V analog feedback at up to 15 kSPS. Dual USARTs allow simultaneous Modbus RTU on one port and a local HMI link on the other, and TWI handles EEPROM or RTC expansion. The industrial -40C to +85C rating and JTAG boundary-scan support cabinet-level production test, making this a low-risk workhorse for control-cabinet retrofits and new machine controllers.
Recommended
Legacy ATmega103 PCB Upgrade
Because the ATmega128 is 100% pin compatible with the ATmega103 per the Microchip datasheet, it is the standard drop-in replacement for extending the life of ATmega103-based printed circuit boards. Engineers solder the ATMEGA128-16AI into the existing 64-TQFP footprint, then use Microchip's 'Replacing ATmega103 by ATmega128' application note to set the M103C compatibility fuse for immediate legacy-code operation or clear it to unlock the full enhanced instruction set and added peripherals. The migration typically doubles usable flash headroom for feature growth while requiring zero PCB rework, which is decisive for certified medical or industrial products where board requalification cost far exceeds the component cost.
Recommended
Embedded Data Logging and Instrumentation
In data-logging instruments, the ATMEGA128-16AI combines an 8-channel 10-bit ADC (approximately 15 kSPS at full resolution) with the XMEM external-memory interface that addresses up to 64KB of additional SRAM, solving the classic problem of buffering measurement data between uploads. One USART streams results to a host or modem while the TWI bus reads a real-time clock and calibration EEPROM. The 4KB internal SRAM holds ring buffers for mid-rate acquisition, and six sleep modes allow battery-backed loggers to idle in power-down at microamp-level currents between timed wakeups from the asynchronous Timer/Counter2 oscillator on TOSC1/TOSC2, which keeps an accurate timebase while the main clock is stopped.
Recommended
Building Automation Controllers
Building automation panels benefit from the ATmega128's dual USARTs (one for BACnet-MS/TP or Modbus RS-485 field bus via a transceiver, one for a local service port), the TWI bus for I/O expanders and sensors, and four timers generating PWM for damper and valve actuators. The 5V-rated operating range tolerates noisy cabinet power rails better than 3.3V MCUs, and the industrial temperature grade covers rooftop and mechanical-room environments. The 128KB flash accommodates a full protocol stack plus OTA-style field-update bootloader in the boot section, enabling firmware updates over the existing field bus without opening the panel - a key maintenance advantage in large deployed estates.
Recommended
Motor Control with PWM
The ATMEGA128-16AI drives DC and stepper motors using PWM from its two 8-bit timers (Timer0 and Timer2, with OC0/OC2 outputs) and the 16-bit Timer1 providing phase-correct or fast PWM with input-capture for encoder timing at up to 16MHz resolution. The 8-channel 10-bit ADC reads shunt-current and back-EMF feedback, while the external interrupt pins on Ports D and E handle quadrature or hall inputs. Because the AVR executes most instructions in one cycle, current-loop algorithms run deterministically without interrupt-latency jitter, delivering clean PWM spectra. Pairing the MCU with an isolated gate driver and a 5V supply creates a compact, low-cost servo or pump controller for industrial equipment.
Recommended
Secure Access and Embedded Security Nodes
The ATmega128 supports AES and DES cryptographic computations via an optional on-chip AES accelerator in certain family variants and provides lock bits plus boot-block protection that form the basis of firmware IP protection and secure bootloader designs. In access-control readers, the dual USARTs interface with a host panel and a contactless reader module, the TWI bus reads keypads or RTC modules, and general-purpose ports drive relays and LEDs directly at 5V logic levels. JTAG can be disabled and locked after production via the JTAGEN fuse, closing the main debug attack surface. The large 128KB flash leaves ample room for future credential-format updates without a hardware change.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA128-16AI β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA128-16AU | ATMEGA1281-16MUR | ATMEGA64-16AI | AT90CAN128-16AU |
|---|---|---|---|---|---|
| Package | 64-TQFP (14x14 mm) | 64-TQFP (14x14 mm) - same | 64-TQFP (14x14 mm) - same | 64-TQFP (14x14 mm) - same | 64-TQFP (14x14 mm) - same |
| Brand | Microchip Technology (Atmel) | Microchip Technology (Atmel) | Microchip Technology | Microchip Technology (Atmel) | Microchip Technology |
| Flash Memory | 128 KB | 128 KB | 128 KB | 64 KB | 128 KB |
| SRAM | 4 KB | 4 KB | 8 KB | 2 KB | 4 KB |
| CPU Speed / Max Frequency | 16 MHz (16 MIPS) | 16 MHz | 16 MHz | 16 MHz | 16 MHz |
| Operating Voltage | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V |
| Special Feature | JTAG debug + boundary scan, 100% ATmega103 pin compatible | Same, RoHS lead-free finish | Doubled SRAM, mega1280-family peripherals | Lower cost, reduced memory | Integrated CAN 2.0A/B controller |
| RoHS / Lead Finish | Leaded (-AI suffix) | RoHS lead-free | RoHS lead-free | Leaded (-AI suffix) | RoHS lead-free |
| Lifecycle Status | Active (mature, in production) | Active | Active | Active (mature) | Active (mature) |
Key Differentiators
- RoHS-compliant drop-in exists on identical silicon (vs ATMEGA128-16AU)
- Double the SRAM on the same footprint (vs ATMEGA1281-16MUR)
- JTAG on-chip debug and boundary scan (vs ATMEGA103-16AI)
- CAN networking without changing footprint (vs AT90CAN128-16AU)
Design Notes
The -16 speed grade requires a 4.5V-5.5V supply; measure the rail under worst-case load with peak ADC and port switching active. Estimate: with roughly 25mA typical active current (datasheet typical at 16MHz/5V) plus up to 40mA total port sink/source loading, budget the 5V regulator for at least 100mA margin. Decouple VCC/AVCC pairs with 100nF ceramics at each pair of supply pins plus a 10uF bulk capacitor. Do not power AVCC from a noisy digital rail - the 10-bit ADC needs a clean AVCC within 0.3V of VCC for specified accuracy.
Route the 16MHz crystal on XTAL1/XTAL2 (pins 12/13) with short traces and guard with a ground ring; program the CKOPT fuse for the >8MHz crystal range to ensure reliable oscillation. Keep AGND (pin 41) and AREF (pin 40) on a quiet analog island: connect AREF to AVCC through an LC filter or decouple to AGND with 100nF, and never drive AREF externally while using the internal reference. Bring the ISP/JTAG header (TCK/TMS/TDO/TDI on PF4-PF7 plus RESET pin 9) to a production header before finalizing layout.
The most frequent field failure mode is incorrect fuse programming: selecting the wrong clock source can render the chip unprogrammable over SPI, requiring a parallel or JTAG rescue. Second, JTAG shares PF4-PF7 with ADC channels 4-7 - clear JTD in MCUCSR (twice in four cycles, per datasheet) or blow the JTAGEN fuse if you need all eight ADC inputs. Third, when using the M103 compatibility mode for legacy code, note that memory maps and enhanced instructions differ; use M103C mode only for direct ATmega103 code migration.
Compliance Information
The -AI suffix historically denotes the leaded (non-RoHS) industrial temperature version; the lead-free RoHS equivalent in the same package is ATMEGA128-16AU. Verify current compliance certificates with Microchip before final purchase.
