ATMEGA128-16AC - 8-bit AVR MCU 16MHz 128KB Flash | Microchip
MPN: ATMEGA128-16AC β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $11.9 | $11.90 |
| 10 | $10.71 | $107.10 |
| 100 | $9.04 | $904.00 |
| 500 | $8.15 | $4,075.00 |
| 1,000 | $7.34 | $7,340.00 |
ATMEGA128-16AC Overview
An 8-bit microcontroller is an integrated circuit that contains a processor core, memory, and programmable input/output peripherals on a single chip, executing control and data-processing tasks in embedded systems. Within the product hierarchy, the ATmega128 sits in the AVR ATmega family of enhanced RISC MCUs, which belongs to the broader class of general-purpose microcontrollers within semiconductor-based embedded processing. The AVR architecture executes most instructions in a single clock cycle, achieving throughput approaching 1 MIPS per MHz.
Key features of the ATMEGA128-16AC include 133 powerful AVR instructions with mostly single-cycle execution, 32 general-purpose working registers, 128KB of ISP Flash with 10,000 write-cycle endurance, 4KB EEPROM rated for 100,000 write cycles, and a rich peripheral set: two 8-bit and two 16-bit timers with PWM, two USARTs, SPI, TWI (I2C-compatible), an 8-channel 10-bit ADC, analog comparator, watchdog timer, and JTAG boundary-scan/on-chip-debug support.
Architecturally, the AVR uses a Harvard structure with separate program and data buses, allowing simultaneous Flash instruction fetch and data access. In-system programmability permits firmware updates after board assembly, and the boot Flash section supports self-programming for field upgrades.
Typical applications include industrial control and automation nodes, embedded instrumentation and test equipment, motor-control and power-supervision systems, and legacy embedded designs requiring extended 128KB program memory with 5V-tolerant I/O.
When designing with this part, remember the -16AC is the commercial temperature grade (0C to +70C); select the -16AI industrial grade for -40C to +85C environments, and budget for a 4.5V to 5.5V supply since 16MHz operation is not supported at 3.3V.
This page synthesizes distributor pricing, drop-in alternatives, complete 64-pin pinout data, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for ATMEGA128-16AC 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 ATMEGA128-16AC (same form factor and footprint) β differing in Package, Communication Interfaces, Core Architecture, Operating Temperature, Supply Voltage Range.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA128A-16AU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA128-16AUR
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA128-16AI
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$5.9 / Unit
View Datasheet βATMEGA128-16ML
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA1281-16MUR
β Drop-Inβ In Stock
$8.78 / Unit
View Datasheet βATMEGA128-16AC Maximum Ratings & Electrical Characteristics
| Core Architecture | AVR 8-bit enhanced RISC |
| Core Size | 8-bit |
| Maximum Clock Frequency | 16 MHz |
| Program Memory Size | 128 KB (64K x 16) Flash |
| Program Memory Type | In-System Programmable Flash |
| EEPROM Size | 4 KB |
| RAM Size | 4 KB SRAM |
| Number of I/O | 53 I/O lines |
| Supply Voltage Range | 4.5 V to 5.5 V |
| Operating Temperature | 0C to +70C (commercial grade) |
| Timers | 2 x 8-bit, 2 x 16-bit with PWM |
| Communication Interfaces | 2 x USART, SPI, TWI (I2C-compatible) |
| ADC Resolution | 10-bit, 8 channels |
| Debug Interface | JTAG (boundary scan and on-chip debug) |
| Package | 64-TQFP (14x14 mm) |
| Mounting Type | Surface Mount |
| Data Converter | A/D 8x10-bit |
ATMEGA128-16AC Pin Configuration
| Pin 1 | PEN β Programming Enable (low during programming) |
| Pin 2 | PE0 (RXD0/PDI) β Port E bit 0 / USART0 receive |
| Pin 3 | PE1 (TXD0/PDO) β Port E bit 1 / USART0 transmit |
| Pin 4 | PE2 (XCK0/AIN0) β Port E bit 2 / USART0 clock / analog comparator input |
| Pin 5 | PE3 (OC3A/AIN1) β Port E bit 3 / Timer3 PWM output A / comparator input |
| Pin 6 | PE4 (OC3B/INT4) β Port E bit 4 / Timer3 PWM output B / external interrupt 4 |
| Pin 7 | PE5 (OC3C/INT5) β Port E bit 5 / Timer3 PWM output C / external interrupt 5 |
| Pin 8 | PE6 (T3/INT6) β Port E bit 6 / Timer3 clock input / external interrupt 6 |
| Pin 9 | PE7 (ICP3/INT7/CLKO) β Port E bit 7 / Timer3 input capture / interrupt 7 / clock out |
| Pin 10 | PB0 (SS) β Port B bit 0 / SPI slave select |
| Pin 11 | PB1 (SCK) β Port B bit 1 / SPI serial clock |
| Pin 12 | PB2 (MOSI) β Port B bit 2 / SPI master data out |
| Pin 13 | PB3 (MISO) β Port B bit 3 / SPI master data in |
| Pin 14 | PB4 (OC0/PWM0) β Port B bit 4 / Timer0 PWM output |
| Pin 15 | PB5 (OC1A) β Port B bit 5 / Timer1 PWM output A |
| Pin 16 | PB6 (OC1B) β Port B bit 6 / Timer1 PWM output B |
| Pin 17 | PB7 (OC2/OC1C) β Port B bit 7 / Timer2 PWM / Timer1 PWM output C |
| Pin 18 | PG3 (TOSC2) β Port G bit 3 / Timer oscillator output (32kHz RTC crystal) |
| Pin 19 | PG4 (TOSC1) β Port G bit 4 / Timer oscillator input |
| Pin 20 | RESET β Reset input (active low) |
| Pin 21 | VCC β Digital supply voltage |
| Pin 22 | GND β Ground |
| Pin 23 | XTAL2 β Crystal oscillator output |
| Pin 24 | XTAL1 β Crystal oscillator input / external clock input |
| Pin 25 | PD0 (SCL/INT0) β Port D bit 0 / TWI clock / external interrupt 0 |
| Pin 26 | PD1 (SDA/INT1) β Port D bit 1 / TWI data / external interrupt 1 |
| Pin 27 | PD2 (TXD1/INT2) β Port D bit 2 / USART1 transmit / interrupt 2 |
| Pin 28 | PD3 (RXD1/INT3) β Port D bit 3 / USART1 receive / interrupt 3 |
| Pin 29 | PD4 (ICP1) β Port D bit 4 / Timer1 input capture |
| Pin 30 | PD5 (XCK1) β Port D bit 5 / USART1 external clock |
| Pin 31 | PD6 (T1) β Port D bit 6 / Timer1 external clock input |
| Pin 32 | PD7 (T2) β Port D bit 7 / Timer2 external clock input |
| Pin 33 | PG0 (WR) β Port G bit 0 / external memory write strobe |
| Pin 34 | PG1 (RD) β Port G bit 1 / external memory read strobe |
| Pin 35 | PC0 (A8) β Port C bit 0 / external memory address bit 8 |
| Pin 36 | PC1 (A9) β Port C bit 1 / external memory address bit 9 |
| Pin 37 | PC2 (A10) β Port C bit 2 / external memory address bit 10 |
| Pin 38 | PC3 (A11) β Port C bit 3 / external memory address bit 11 |
| Pin 39 | PC4 (A12) β Port C bit 4 / external memory address bit 12 |
| Pin 40 | PC5 (A13) β Port C bit 5 / external memory address bit 13 |
| Pin 41 | PC6 (A14) β Port C bit 6 / external memory address bit 14 |
| Pin 42 | PC7 (A15) β Port C bit 7 / external memory address bit 15 |
| Pin 43 | PG2 (ALE) β Port G bit 2 / external memory address latch enable |
| Pin 44 | VCC β Digital supply voltage |
| Pin 45 | GND β Ground |
| Pin 46 | PA7 (AD7) β Port A bit 7 / external memory address/data bit 7 |
| Pin 47 | PA6 (AD6) β Port A bit 6 / external memory address/data bit 6 |
| Pin 48 | PA5 (AD5) β Port A bit 5 / external memory address/data bit 5 |
| Pin 49 | PA4 (AD4) β Port A bit 4 / external memory address/data bit 4 |
| Pin 50 | PA3 (AD3) β Port A bit 3 / external memory address/data bit 3 |
| Pin 51 | PA2 (AD2) β Port A bit 2 / external memory address/data bit 2 |
| Pin 52 | PA1 (AD1) β Port A bit 1 / external memory address/data bit 1 |
| Pin 53 | PA0 (AD0) β Port A bit 0 / external memory address/data bit 0 |
| Pin 54 | PF0 (ADC0) β Port F bit 0 / ADC channel 0 |
| Pin 55 | PF1 (ADC1) β Port F bit 1 / ADC channel 1 |
| Pin 56 | PF2 (ADC2) β Port F bit 2 / ADC channel 2 |
| Pin 57 | PF3 (ADC3) β Port F bit 3 / ADC channel 3 |
| Pin 58 | PF4 (ADC4/TCK) β Port F bit 4 / ADC channel 4 / JTAG test clock |
| Pin 59 | PF5 (ADC5/TMS) β Port F bit 5 / ADC channel 5 / JTAG test mode select |
| Pin 60 | PF6 (ADC6/TDO) β Port F bit 6 / ADC channel 6 / JTAG test data out |
| Pin 61 | PF7 (ADC7/TDI) β Port F bit 7 / ADC channel 7 / JTAG test data in |
| Pin 62 | AREF β ADC reference voltage |
| Pin 63 | AGND β Analog ground |
| Pin 64 | AVCC β Analog supply voltage for port F and ADC |
Typical Applications
ATMEGA128-16AC is suitable for 6 applications: Industrial Control and Automation, Embedded Instrumentation and Test Equipment, Legacy AVR Design Maintenance, Motor Control and Actuator Systems, Communication Gateways and Serial Concentrators, Education and Hobbyist Development Platforms.
Industrial Control and Automation
The ATMEGA128-16AC fits industrial control nodes because its 53 I/O lines, four PWM-capable timers, and dual USARTs allow simultaneous sensor polling, actuator drive, and Modbus-style serial communication without external expanders. Its 128KB ISP Flash accommodates large state machines and field-updatable firmware via the boot-loader section, while the 4KB EEPROM retains calibration constants through power cycles. Operating from a 4.5V to 5.5V rail matches legacy 5V industrial signal levels, giving noise margin that 3.3V MCUs lack on long cable runs. The commercial 0C to +70C rating suits panel-mounted controllers; specify the -16AI grade for outdoor or unconditioned enclosures.
Recommended
Embedded Instrumentation and Test Equipment
Bench instruments, data loggers, and custom test fixtures benefit from the ATMEGA128-16AC's 8-channel 10-bit ADC for multi-sensor acquisition and its JTAG port for in-circuit debugging during development. The 16MHz AVR core delivers roughly 16 MIPS, sufficient for local averaging, threshold comparison, and menu-driven user interfaces on character LCDs via TWI or parallel buses. The external memory interface (ports A, C, and PG0-PG2 ALE/WR/RD pins) can address external SRAM beyond the internal 4KB when long acquisition buffers are required. Its 100,000-cycle EEPROM endurance suits measurement calibration storage in instruments recalibrated periodically.
Recommended
Legacy AVR Design Maintenance
Thousands of shipping products were built around the original ATmega128 and now need continued sourcing as the original die becomes harder to buy in volume. The ATMEGA128-16AC and its drop-in successor ATMEGA128A-16AU keep such boards serviceable without any PCB change: same 64-TQFP footprint, same pinout, same register map, and same ISP programming flow through SPI. Rochester Electronics also supplies original-die parts for long-tail programs. Engineering teams maintaining legacy firmware should validate the boot-loader flash procedure on the ATmega128A, whose boot section timing is marginally faster on the new process, then standardize on the A-variant for future builds.
Recommended
Motor Control and Actuator Systems
With two 8-bit and two 16-bit timers offering multiple PWM outputs (OC0, OC1A/B/C, OC2, OC3A/B/C), the ATMEGA128-16AC can drive brushed DC, stepper, and small three-phase actuator stages directly at 5V logic. The external interrupt pins INT0-INT7 plus the analog comparator support encoder feedback and over-current trip logic with hardware latency below one timer clock. Running at 16MHz gives 1 MIPS-per-MHz throughput for executing PID loops at multi-kilohertz rates in C. Gate-driver ICs on the SPI bus extend the MCU to power MOSFET half-bridges, while the watchdog timer enforces fail-safe shutdown if firmware hangs.
Recommended
Communication Gateways and Serial Concentrators
The two independent hardware USARTs on the ATMEGA128-16AC make it a natural protocol bridge: for example, translating RS-485 Modbus RTU on one port to RS-232 diagnostics on the other, or combining multiple field devices into a single upstream link. Hardware SPI and TWI add two more simultaneous buses for sensors, RTCs, and EEPROMs without software bit-banging overhead. The 128KB Flash holds generous protocol stacks, and the boot section permits field firmware updates over the serial link, minimizing maintenance trips. The 5V I/O directly drives optocoupler-based RS-485 front ends commonly used in industrial networks.
Recommended
Education and Hobbyist Development Platforms
The ATmega128 remains popular in university embedded-systems courses and hobbyist platforms because AVR toolchains (AVR-GCC, avrdude, and Arduino-compatible cores such as MegaCore for ATmega128) are free and mature. The JTAG port allows students to set breakpoints and inspect registers in real hardware, a capability many modern MCUs gate behind proprietary debuggers. Its through-documented 5V operation tolerates wiring mistakes better than 3.3V parts, and the 64-pin TQFP on adapter boards is approachable for breadboard prototyping. The 133-instruction RISC set is small enough to teach assembly fundamentals yet powerful enough for term projects spanning displays, sensors, and motors.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA128-16AC β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA128A-16AU | ATMEGA128-16AUR | ATMEGA128-16AI | ATMEGA128-16ML | ATMEGA1281-16MUR |
|---|---|---|---|---|---|---|
| Package | 64-TQFP (14x14) | 64-TQFP (14x14) - same | 64-TQFP (14x14) - same | 64-TQFP (14x14) - same | 64-TQFP (14x14) - same | 64-TQFP (14x14) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Max Clock Frequency | 16 MHz | 16 MHz | 16 MHz | 16 MHz | 16 MHz | 16 MHz |
| Flash Memory | 128 KB | 128 KB | 128 KB | 128 KB | 128 KB | 128 KB |
| SRAM | 4 KB | 4 KB | 4 KB | 4 KB | 4 KB | 8 KB |
| Pin Compatibility | Reference (ATmega128 pinout) | Pin-to-pin compatible | Pin-to-pin compatible | Pin-to-pin compatible | Pin-to-pin compatible | Different peripheral mapping - verify before reuse |
Key Differentiators
- Lower power consumption on the newer process (vs ATMEGA128-16AC (baseline))
- Extended temperature range for harsh environments (vs ATMEGA128-16AUR)
- Legacy-silicon sourcing continuity (vs ATMEGA1281-16MUR)
Design Notes
Supply the ATMEGA128-16AC from a clean 4.5V to 5.5V rail; 16MHz operation is only qualified at 5V-class voltages per the Microchip datasheet speed-versus-voltage curve. Place 100nF ceramic decoupling capacitors at both VCC pins (21 and 44) within 5 mm of each pin, plus a 10uF bulk capacitor near the regulator. Tie AVCC (pin 64) to VCC through a 10uH LC filter when ADC accuracy matters, and never leave AVCC below VCC - the datasheet warns AVCC must not exceed VCC by more than 0.3V.
Connect AGND (pin 63) to a star-ground point shared with the ADC reference return path to keep switching currents out of the analog domain. Use AREF (pin 62) with a 100nF capacitor to AGND; do not connect an external reference while the internal reference is enabled. Keep the XTAL1/XTAL2 crystal traces short and ring them with a ground guard. Because JTAG shares PF4-PF7 with ADC4-ADC7, plan pin usage early: program the JTAGEN fuse off only after confirming no debugger access is needed.
Do not attempt 16MHz operation below 4.5V - overclocking below the datasheet voltage curve causes marginal Flash execution and intermittent resets. PEN (pin 1) must be pulled high through a 10k resistor for normal operation; only pull it low during high-voltage parallel programming. RESET is active low with an internal pull-up, but add an external 10k pull-up and 100nF cap for noisy environments. When migrating to ATMEGA128A-16AU, re-verify boot-loader flash timing since the newer die writes marginally faster.
Compliance Information
Compliance status not stated in the provided Verified Web Data; confirm RoHS/REACH/lead-free status on the Microchip product page or certificate of conformance before procurement.