ATMEGA128A-AN - 8-bit AVR MCU 128KB Flash 16MHz | Microchip
MPN: ATMEGA128A-AN ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.75 | $2.75 |
| 10 | $2.55 | $25.50 |
| 100 | $2.35 | $235.00 |
| 500 | $2.15 | $1,075.00 |
| 1,000 | $1.95 | $1,950.00 |
ATMEGA128A-AN Overview
An 8-bit AVR microcontroller is a Harvard-architecture RISC processor that executes most instructions in a single clock cycle. Within the power-management hierarchy, MCUs such as the ATmega128A integrate CPU, program memory, data memory, timers and peripherals on one die, replacing multi-chip solutions in embedded control systems. The ATmega128A belongs to the AVR ATmega family and the broader microcontroller unit (MCU) category.
Key features include 135 powerful RISC instructions, 32 general-purpose working registers, four flexible Timer/Counters with compare modes and PWM, a Real Time Counter, and 2 USARTs. Per the Microchip datasheet summary (Atmel-8151S), the device also provides one byte-oriented Two-Wire Interface (I2C), SPI, an 8-channel 10-bit ADC, and JTAG boundary-scan and on-chip debugging.
Architecturally, the AVR core uses single-cycle instruction execution with a deep pipeline, achieving near-1 MIPS per MHz throughput. Read-while-write Flash allows code updates during operation. The improved manufacturing process of the A-variant delivers significantly lower power consumption than the original ATmega128.
Typical applications include legacy industrial control upgrade, embedded instrumentation, motor-control front ends, and building automation nodes. Its 100% pin compatibility with ATmega103 and ATmega128 makes it ideal for PCB redesign-free refreshes.
Design consideration: at 16MHz and 5V, keep decoupling close to all VCC pins and observe XTAL1/XTAL2 layout; use the Migration application note AVR525 when replacing ATmega128.
This page adds value beyond the datasheet by synthesizing distributor pricing, drop-in alternatives, a full 64-pin pinout table, and practical design notes.
Drop-in alternatives for ATMEGA128A-AN — 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-AN (same form factor and footprint) — differing in Flash Memory, Timers/Counters, Operating Temperature, Package, ADC.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA128-16AN
✅ Drop-In✓ In Stock
$7.44 / Unit
View Datasheet →ATMEGA128A-AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$4.3 / Unit
View Datasheet →ATMEGA128L-8AN
✅ Drop-In📋 Reference alternative (not in catalog)
ATMEGA128-16AI
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$5.9 / Unit
View Datasheet →ATMEGA128A-AN Maximum Ratings & Electrical Characteristics
| Core | AVR 8-bit RISC |
| Flash Memory | 128 KB (In-System Programmable, read-while-write) |
| EEPROM | 4 KB |
| SRAM | 4 KB |
| Maximum Clock Frequency | 16 MHz |
| General Purpose I/O | 53 lines |
| Working Registers | 32 general purpose |
| Timers/Counters | 4 flexible Timer/Counters with compare modes and PWM |
| USART | 2 |
| Real Time Counter | Yes (RTC) |
| Package | TQFP-64 |
| Operating Temperature | -40C to +105C |
| Mounting Type | Surface Mount |
| RoHS Status | Green (per LCSC/Mouser listing) |
ATMEGA128A-AN Pin Configuration
| Pin 1 | PEN — Programming enable (per datasheet) |
| Pin 2 | PE0 — RXD0/PDI - USART0 receive |
| Pin 3 | PE1 — TXD0/PDO - USART0 transmit |
| Pin 4 | PE2 — XCK0/AIN0 |
| Pin 5 | PE3 — AIN1/OC3A |
| Pin 6 | PE4 — OC3B/INT4 |
| Pin 7 | PE5 — OC3C/INT5 |
| Pin 8 | PE6 — T3/INT6 |
| Pin 9 | PE7 — ICP3/INT7/CLKO |
| Pin 10 | VCC — Digital supply voltage |
| Pin 11 | GND — Ground |
| Pin 12 | PG0 — WR - external memory write strobe |
| Pin 13 | PG1 — RD - external memory read strobe |
| Pin 14 | PG2 — ALE - external memory address latch enable |
| Pin 15 | PC0 — A8 - external memory address bus |
| Pin 16 | PC1 — A9 |
| Pin 17 | PC2 — A10 |
| Pin 18 | PC3 — A11 |
| Pin 19 | PC4 — A12 |
| Pin 20 | PC5 — A13 |
| Pin 21 | PC6 — A14 |
| Pin 22 | PC7 — A15 |
| Pin 23 | AREF — ADC reference voltage |
| Pin 24 | AGND — Analog ground |
| Pin 25 | AVCC — Analog supply voltage |
| Pin 26 | PA7 — AD7 - address/data bus, ADC7 |
| Pin 27 | PA6 — AD6, ADC6 |
| Pin 28 | PA5 — AD5, ADC5 |
| Pin 29 | PA4 — AD4, ADC4 |
| Pin 30 | PA3 — AD3, ADC3 |
| Pin 31 | PA2 — AD2, ADC2 |
| Pin 32 | PA1 — AD1, ADC1 |
| Pin 33 | PA0 — AD0, ADC0 |
| Pin 34 | PB0 — SS - SPI slave select |
| Pin 35 | PB1 — SCK - SPI clock |
| Pin 36 | PB2 — MOSI - SPI master out |
| Pin 37 | PB3 — MISO - SPI master in |
| Pin 38 | PB4 — OC0/PWM0 |
| Pin 39 | PB5 — OC1A - PWM output |
| Pin 40 | PB6 — OC1B - PWM output |
| Pin 41 | PB7 — OC2/OC1C - PWM output |
| Pin 42 | PF0 — ADC0 |
| Pin 43 | PF1 — ADC1 |
| Pin 44 | PF2 — ADC2 |
| Pin 45 | PF3 — ADC3 |
| Pin 46 | PF4 — ADC4/TCK - JTAG test clock |
| Pin 47 | PF5 — ADC5/TMS - JTAG test mode select |
| Pin 48 | PF6 — ADC6/TDO - JTAG test data out |
| Pin 49 | PF7 — ADC7/TDI - JTAG test data in |
| Pin 50 | GND — Ground |
| Pin 51 | VCC — Digital supply voltage |
| Pin 52 | GND — Ground |
| Pin 53 | VCC — Digital supply voltage |
| Pin 54 | PD0 — SCL/INT0 - TWI clock, external interrupt 0 |
| Pin 55 | PD1 — SDA/INT1 - TWI data, external interrupt 1 |
| Pin 56 | PD2 — RXD1/INT2 - USART1 receive |
| Pin 57 | PD3 — TXD1/INT3 - USART1 transmit |
| Pin 58 | PD4 — ICP1 - Timer1 input capture |
| Pin 59 | PD5 — XCK1 - USART1 external clock |
| Pin 60 | PD6 — T1 - Timer1 external clock input |
| Pin 61 | PD7 — T2 - Timer2 external clock input |
| Pin 62 | RESET — Reset input |
| Pin 63 | XTAL2 — Oscillator output |
| Pin 64 | XTAL1 — Oscillator input |
Typical Applications
ATMEGA128A-AN is suitable for 6 applications: Legacy Industrial Control Board Refresh, Embedded Instrumentation and Data Loggers, Multi-Protocol Communication Nodes, Motor Control and PWM Actuator Drive, Educational and Maker Platforms, ATmega103 Replacement in Existing Designs.
Legacy Industrial Control Board Refresh
The ATMEGA128A-AN is a functionally identical drop-in replacement for the ATmega128, per Microchip application note AVR525, allowing production lines running the original ATmega128 to be refreshed without PCB redesign or firmware changes. The improved process delivers significantly lower power consumption, which reduces thermal load in sealed industrial enclosures. With 128KB read-while-write Flash, 4KB EEPROM for parameter storage and two USARTs for fieldbus links, it maintains the memory map and peripheral set legacy code expects. Verify only the minor electrical characteristic differences documented in the separate ATmega128A datasheet before mass production.
Recommended
Embedded Instrumentation and Data Loggers
Instrumentation front ends benefit from the ATMEGA128A-AN's combination of 128KB program Flash, 4KB EEPROM for calibration constants and 53 GPIO lines for multiplexed sensor interfaces. Four Timer/Counters with compare modes and PWM support precise sampling triggers and actuator drive, while the Real Time Counter keeps timestamps during low-power operation. The 16MHz AVR core provides roughly 16 MIPS, sufficient for filtering and protocol handling without an external coprocessor. JTAG on-chip debugging through PF4-PF7 shortens field-firmware validation cycles during development of measurement products.
Recommended
Multi-Protocol Communication Nodes
With two independent USARTs, an SPI port and a byte-oriented Two-Wire Interface (I2C) per the Microchip datasheet, the ATMEGA128A-AN bridges RS-232/RS-485 links with sensor buses in building automation and telemetry nodes. At 16MHz the core sustains simultaneous full-duplex UART traffic and TWI transactions while retaining headroom for application logic. 53 GPIO lines handle addressable I/O expansion, and 4KB EEPROM stores node addresses and configuration persistently. Read-while-write Flash allows field firmware updates over the communication link without halting the running application - a practical benefit for remotely deployed nodes.
Recommended
Motor Control and PWM Actuator Drive
The four flexible Timer/Counters with compare modes and PWM outputs - including OC0, OC1A/OC1B/OC1C and OC3A/OC3B/OC3C - give the ATMEGA128A-AN up to seven hardware PWM channels suitable for DC motor speed control, LED dimming and servo actuation. External memory pins PA0-PA7 and PC0-PC7 plus WR/RD/ALE (PG0-PG2) support expanded addressing in motion controllers needing external RAM or memory-mapped peripherals. INT4-INT7 external interrupts on PE4-PE7 capture quadrature encoder edges with low latency. The -40C to +105C rating supports thermally demanding drive cabinets.
Recommended
Educational and Maker Platforms
The ATmega128 family remains popular in education because the AVR RISC core executes most of its 135 instructions in a single cycle, making assembly and C timing behavior transparent to students. The open-source MegaCore Arduino hardware package explicitly supports the ATmega128 family, enabling Arduino-style development on this part. With 53 GPIO lines, on-chip 10-bit sensing via the ADC pins PF0-PF3/PA pins, and JTAG for classroom debug probes, a single TQFP-64 board covers digital, analog and communication labs. The 128KB Flash accommodates larger projects without the memory ceiling of smaller ATmega parts.
Recommended
ATmega103 Replacement in Existing Designs
According to the Microchip datasheet summary, the ATmega128A is 100% pin compatible with the ATmega103 and can replace it on current printed circuit boards, making the ATMEGA128A-AN the standard migration path for designs built around the discontinued ATmega103. The application note 'Replacing ATmega103 by ATmega128A' documents fuse, register and behavioral differences the designer must address in firmware. Because the footprint and pinout are unchanged, a soldering operation alone completes the hardware migration, while the doubled Flash and added peripherals (second USART, extra timers) become available for feature growth.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA128A-AN — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA128-16AN | ATMEGA128A-AU | ATMEGA128L-8AN | ATMEGA128-16AI |
|---|---|---|---|---|---|
| Package | TQFP-64 | TQFP-64 - same | TQFP-64 - same | TQFP-64 - same | TQFP-64 - same |
| Brand | Microchip Technology | Microchip Technology (Atmel) | Microchip Technology (Atmel) | Microchip Technology (Atmel) | Microchip Technology (Atmel) |
| Flash | 128 KB | 128 KB | 128 KB | 128 KB | 128 KB |
| SRAM | 4 KB | 4 KB | 4 KB | 4 KB | 4 KB |
| Max Clock | 16 MHz | 16 MHz | 16 MHz | 8 MHz (-50%) | 16 MHz |
| Process Generation | A (improved, lower power) | Original ATmega128 | A (improved) | L (low voltage) | Original ATmega128 |
| Drop-in Compatibility | Reference part | Functionally identical per AVR525 | Same die, pin-to-pin | Pin-compatible, clock/voltage derated | Pin-to-pin, same family |
Key Differentiators
- Lower power consumption via improved process (vs ATMEGA128-16AN)
- Full-speed 16MHz operation (vs ATMEGA128L-8AN)
- ATmega103 board compatibility (vs ATMEGA128A-AU)
Design Notes
Decouple every VCC pin (10, 51, 53) with 100nF ceramic capacitors placed within 2-3mm of the pin, plus one 4.7-10uF bulk capacitor per supply rail. Connect AVCC (pin 25) to VCC through a low-pass LC filter when using the ADC, and tie AREF (pin 23) to ground via 100nF unless an external reference is used. The A-process die draws less current than the original ATmega128, so existing designs may see slightly lower rail loading after substitution.
Keep XTAL1 (pin 64) and XTAL2 (pin 63) traces as short as possible with the crystal and load capacitors placed directly adjacent; guard them with ground pour away from switching signals. PEN (pin 1) must be handled per the datasheet programming-enable requirements - do not leave floating in production boards if ISP is used. Route the JTAG chain (PF4-PF7) to a 2x5 header for on-chip debug access; retrofitting JTAG later is difficult on dense TQFP-64 layouts.
When migrating from ATmega128 to ATmega128A, consult Microchip application note AVR525 (doc8166): although the part is a functionally identical drop-in, some electrical characteristics differ due to the new process, and the devices have separate datasheets. When migrating from ATmega103, note the application note 'Replacing ATmega103 by ATmega128A' - fuse defaults, register addresses and MCU control behavior differ even though the pinout is 100% compatible.
Compliance Information
Listed as 'Green' by LCSC and Mouser, indicating RoHS/halogen-free compliance. Full REACH and conflict-minerals declarations not found in provided data.
