ATMEGA128-16MI - 8-Bit AVR MCU 128KB Flash 16MHz | Microchip
MPN: ATMEGA128-16MI ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $15.01 | $15.01 |
| 10 | $14.26 | $142.60 |
| 100 | $12.76 | $1,276.00 |
| 500 | $11.56 | $5,780.00 |
| 1,000 | $10.51 | $10,510.00 |
ATMEGA128-16MI Overview
An 8-bit AVR microcontroller is a Harvard-architecture MCU in which program memory and data memory use separate buses, allowing most instructions to execute in a single clock cycle. Within the power-management hierarchy, the ATmega128 sits at the top of the classic ATmega family, acting as the system brain that orchestrates peripherals, sensors, and communication interfaces in embedded systems.
Key features include the AVR enhanced RISC core with 133 powerful instructions, 128 KB self-programmable Flash with a 2-wire (I2C/TWI) or SPI programming interface, two 8-bit and two 16-bit timers/counters, and rich connectivity: two UARTs, SPI, TWI (I2C), and an 8-channel 10-bit ADC. The 16 MHz speed grade (-16 suffix) supports industrial automation, metering, and motor-control workloads that smaller ATmega parts cannot handle.
Technically, the ATmega128 implements JTAG (IEEE 1149.1 compliant) for on-chip debugging and boundary scan, six sleep modes including power-down and power-save for battery designs, and an internal RC oscillator option alongside an external crystal input. Byte-writable EEPROM retains calibration data through power cycles, and the bootloader section permits field firmware updates over UART or SPI.
Typical applications include industrial control panels, HVAC and building automation, battery-powered data loggers, and legacy embedded products upgraded from smaller ATmega devices. The 64-QFN exposed-pad package suits space-constrained boards needing 53 general-purpose I/O lines.
A key design consideration: the MLF/QFN pad requires a solid ground pour with thermal vias; the -MI temperature range and QFN footprint must be confirmed against the TQFP (AU/AI) variants during layout migration.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA128-16MI — 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 ATMEGA128-16MI (same form factor and footprint) — differing in ADC Channels, Package, Program Memory Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA128A-16MI
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
ATMEGA1281-16MUR
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$8.78 / Unit
View Datasheet →ATMEGA128-16MI Maximum Ratings & Electrical Characteristics
| Core Processor | AVR 8-bit RISC |
| Core Size | 8-bit |
| Speed | 16 MHz |
| Program Memory Size | 128 KB (128K x 8) Flash |
| EEPROM Size | 4 KB |
| RAM Size | 4 KB SRAM |
| Number of I/O | 53 |
| Peripherals | SPI, UART, TWI (I2C), JTAG, PWM, WDT, Brown-out Detect/Reset |
| ADC Resolution | 10-bit |
| ADC Channels | 8 |
| Operating Voltage | 4.5 V to 5.5 V |
| Oscillator Type | Internal |
| Package | 64-VFQFN Exposed Pad |
| Mounting Type | Surface Mount |
| Data Converters | A/D 8x10-bit |
| Connectivity | SPI, UART/USART, TWI |
ATMEGA128-16MI 64-vfqfn exposed pad Pin Configuration Guide
Pin configuration for ATMEGA128-16MI (64-vfqfn exposed pad 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 ATMEGA128-16MI.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA128-16MI is suitable for 6 applications: Industrial Control Panels, Building Automation and HVAC, Battery-Powered Data Loggers, Motor Control and PWM Actuation, Legacy Product Maintenance and AVR Upgrades, Metering and Sensor Hubs.
Industrial Control Panels
The ATMEGA128-16MI fits industrial panel controllers because its 53 GPIO lines, dual UARTs, SPI, and TWI (I2C) can simultaneously drive relays, an HMI, and field sensors. The 16 MHz AVR core delivers 16 MIPS single-cycle throughput, sufficient for deterministic scanning of digital inputs and PID loops, while the 128 KB self-programmable Flash leaves room for protocol stacks and OTA-style bootloader updates over UART. The 8-channel 10-bit ADC reads 0-10 V-scaled analog transducers, and the brown-out detector plus watchdog timer ensure safe restart after mains disturbances. The exposed-pad VFQFN provides a solid ground reference for noise immunity in electrically harsh cabinets.
Recommended
Building Automation and HVAC
In HVAC controllers, the ATMEGA128-16MI handles multi-zone sensing and actuation using its 8-channel 10-bit ADC for temperature and humidity inputs and TWI (I2C) for digital sensor buses. The 4 KB EEPROM stores zone setpoints and calibration tables across power cycles, while 4 KB SRAM buffers communication frames for Modbus-style UART links (two UARTs available). Six sleep modes, including power-save with an asynchronous timer, keep standby consumption low in thermostat-class products. The 128 KB Flash accommodates a full control algorithm, bootloader, and diagnostic logging without external memory, reducing BOM cost and board area in the 64-QFN footprint.
Recommended
Battery-Powered Data Loggers
The ATMEGA128-16MI serves data-logger designs that need substantial Flash for logged records and multiple communication channels. Its 128 KB Flash can hold both firmware and a reserve log partition written via self-programming, while the 4 KB EEPROM stores configuration wear-levelling structures. Power-save and power-down sleep modes reduce average current between sampling intervals, and the watchdog guarantees recovery from brownouts in the field. One UART streams data over RS-485 while the second services a local service port; SPI connects fast ADCs or SD-card media. Designers should prefer the 8 MHz voltage range variant when the rail is below 4.5 V, since the 16 MHz grade is 5 V-only.
Recommended
Motor Control and PWM Actuation
With four timers (two 8-bit, two 16-bit) providing multiple PWM channels, the ATMEGA128-16MI can drive brushed-DC and stepper motor stages with software or hardware PWM at 16 MHz resolution. The 10-bit ADC supports back-EMF and current sampling for closed-loop control, and the comparator input enables cycle-by-cycle protection schemes. The 53 GPIO lines allow direct interfacing with limit switches, encoders, and HMI buttons in one MCU, replacing multi-chip solutions. Designers typically pair the MCU with Infineon gate drivers or smart switches; the exposed-pad package grounds switching noise effectively, though layout care is needed to keep ADC references clean from PWM return currents.
Recommended
Legacy Product Maintenance and AVR Upgrades
Many installed-base products were designed around the ATmega128; the ATMEGA128-16MI keeps those boards in production. Because the ATmega128A variant is pin-to-pin and firmware-compatible, service organizations can qualify replacements quickly. The JTAG interface (IEEE 1149.1) supports boundary-scan test and on-chip debugging on existing fixtures, and the SPI-based ISP path allows field reflashing without desoldering. The 64-VFQFN package matches legacy MLF footprints directly. For designs migrating from the 40-pin ATmega8515 or ATmega103, the ATmega128 offers a documented register-level migration path with expanded Flash, EEPROM, and peripheral set in the MegaCore open-source Arduino support package.
Recommended
Metering and Sensor Hubs
Electricity, water, and gas meter front-ends benefit from the ATMEGA128-16MI's combination of a 10-bit ADC, hardware TWI and SPI buses, and large self-programmable Flash for tariff tables and event logs. The dual UARTs link a metrology front-end on one channel and an AMR/AMI communication modem on the other. EEPROM retains billing-relevant calibration constants through battery swaps, and the brown-out detector plus power-on reset guarantee state integrity during outages. The 16 MHz core executes CRC and AES-class software routines at acceptable speed, while the 64-QFN exposed-pad package supports compact, conformally coated meter PCBs with solid grounding for front-end accuracy.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA128-16MI — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA128A-16MI | ATMEGA1281-16MUR |
|---|---|---|---|
| Package | 64-VFQFN Exposed Pad | 64-VFQFN Exposed Pad - same | 64-VQFN (different die pinout) |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology |
| Core / Speed | AVR 8-bit, 16 MHz | AVR 8-bit, 16 MHz | AVR 8-bit, 16 MHz |
| Flash | 128 KB | 128 KB | 128 KB |
| EEPROM | 4 KB | 4 KB | 4 KB |
| SRAM | 4 KB | 4 KB | 8 KB |
| I/O Count | 53 | 53 | 54 |
| Special Features | JTAG OCD + boundary scan | JTAG OCD + boundary scan | RTC, real-time counter; debugWIRE-style OCD (no JTAG) |
| Firmware Compatibility | Reference (ATmega128) | 100% compatible | Register map differs - porting required |
Key Differentiators
- JTAG on-chip debug and boundary scan (vs ATMEGA1281-16MUR)
- True drop-in second source within family (vs ATMEGA128A-16MI)
- Trade-off: 5 V-only operation (vs ATMEGA1281-16MUR)
Design Notes
The 64-VFQFN exposed pad is the primary ground connection. Create a solder-paste window array under the exposed pad and connect it to the ground plane with an array of thermal vias (typically 4x4, 0.3 mm drills). Insufficient pad soldering is the most common cause of intermittent resets and ADC noise on MLF-packaged AVRs. Follow the land-pattern guidance in the Microchip ATmega128 datasheet and consider X2 inspection since the pad is hidden after reflow.
The -16 speed grade is specified only from 4.5 V to 5.5 V. Running the part at 3.3 V risks out-of-spec timing margins. Decouple VCC with 100 nF ceramics at each supply pair plus a 10 uF bulk capacitor, placed within a few millimeters of the pins. If your rail can droop below 4.5 V, enable the internal brown-out detector at an appropriate threshold (e.g., 4.0 V) so the MCU does not execute corrupted code during supply sags.
On the ATmega128, the JTAG-enable fuse is programmed by default; JTAG pins PC7-PC2 are not usable as GPIO unless the fuse is cleared. Also note the USART1 and ADC multiplexing conflicts on Port F, and that the ATmega103 compatibility mode fuse must be disabled to access the full register map and I/O set. These three fuse settings (JTAGEN, M103C, and clock sources) account for most bring-up failures when migrating designs from smaller ATmega devices.
Compliance Information
Compliance status was not stated in the provided web data. Verify RoHS/REACH status on the official Microchip product page for ATMEGA128-16MI before procurement.
