ATMEGA128L-8MN - 8MHz AVR MCU 128KB Flash 64-QFN | Microchip
MPN: ATMEGA128L-8MN β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $11.42 | $11.42 |
| 10 | $10.28 | $102.80 |
| 100 | $9.13 | $913.00 |
| 500 | $8.44 | $4,220.00 |
| 1,000 | $7.68 | $7,680.00 |
ATMEGA128L-8MN Overview
An 8-bit AVR microcontroller is a self-contained computing IC that integrates a RISC processor core, program memory, data memory, and peripherals such as timers, UARTs, SPI, and ADCs on a single die. Within the power-management and embedded-systems hierarchy, MCUs sit at the application layer, executing user firmware for control, sensing, and communication tasks in everything from industrial automation to consumer devices.
Key features include 133 powerful instructions with most executing in a single clock cycle, 53 programmable I/O lines, a JTAG interface for on-chip debugging and boundary-scan, and two 8-bit plus two 16-bit timers with PWM capability. The ATmega128 architecture also integrates dual USARTs, SPI, and a two-wire (I2C-compatible) interface, allowing multiple communication channels simultaneously.
Technically, the AVR enhanced RISC core couples a large register file of 32 general-purpose working registers directly to the ALU, avoiding the accumulator bottleneck of classic 8-bit architectures. The -8MN suffix denotes the 8 MHz L-version rated from 2.7 V to 5.5 V, while the MN package code identifies the lead-free 64-pad QFN with a 9x9 mm body suitable for compact, thermally efficient layouts.
Typical applications include industrial control panels, building automation and sensor hubs, battery-powered instruments where the low-voltage L-grade supports 3.3 V operation, and legacy ATmega128 designs maintained by Rochester Electronics distribution.
Design consideration: when running from a 3.3 V rail, use the internal RC oscillator or a crystal rated for the low-voltage frequency limit; at 5 V the L-grade remains limited to 8 MHz, so choose the ATMEGA128-16MN variant only when a 4.5-5.5 V supply and 16 MHz operation are acceptable.
This page synthesizes distributor pricing context, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA128L-8MN 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 ATMEGA128L-8MN (same form factor and footprint) β differing in Package, Communication Interfaces, SRAM, Timers/Counters, Supply Voltage Range.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
No drop-in alternatives available for this product.
Request AlternativesATMEGA128L-8MN Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Program Memory Size | 128 KB (64K x 16) Flash |
| SRAM Size | 4 KB (4K x 8) |
| EEPROM Size | 4 KB |
| Maximum Clock Speed | 8 MHz |
| Supply Voltage Range | 2.7 V to 5.5 V |
| I/O Count | 53 programmable I/O lines |
| ADC | 8-channel, 10-bit |
| JTAG Interface | Yes (on-chip debug and boundary-scan) |
| Timers | 2 x 8-bit, 2 x 16-bit with PWM |
| Communication Interfaces | 2 x USART, SPI, 2-wire (I2C-compatible) |
| Instruction Set | 133 instructions, most single-cycle |
| Package | 64-QFN (9x9 mm) |
| Mounting Type | Surface Mount |
| Lifecycle Status | Active |
| Series | AVR ATmega |
ATMEGA128L-8MN 64-qfn (9x9 mm) Pin Configuration Guide
Pin configuration for ATMEGA128L-8MN (64-qfn (9x9 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 ATMEGA128L-8MN.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA128L-8MN is suitable for 6 applications: Industrial Control and Automation, Battery-Powered Instrumentation, Building Automation and Sensor Hubs, Embedded Networking and Communication Devices, Legacy ATmega128 Design Continuity, Motor Control and PWM Actuation.
Industrial Control and Automation
The ATMEGA128L-8MN fits industrial control nodes that need generous 128 KB code space for protocol stacks, HMI logic, and diagnostics while running from either a 24 V-derived 5 V rail or a 3.3 V logic supply within its 2.7-5.5 V range. Dual USARTs allow simultaneous Modbus RTU and inter-board communication, SPI and TWI handle ADC and EEPROM expansion, and the JTAG interface supports on-chip debugging during production ramp. Its 53 I/O lines directly drive relays, optocouplers, and keypad matrices without glue logic. Design consideration: at 5 V the ADC reference and I/O thresholds align with common industrial 0-5 V sensor signaling, while the 8 MHz ceiling keeps EMI manageable in DIN-rail enclosures with long wiring harnesses.
Recommended
Battery-Powered Instrumentation
The 2.7 V floor of the ATMEGA128L-8MN allows direct operation from three NiMH cells or a regulated 3.3 V lithium supply, which is why the L-grade is favored in portable measurement instruments, data loggers, and handheld meters. The AVR power-management unit offers idle, power-down, and power-save modes so the MCU can sleep between sampling events, and the 8-channel 10-bit ADC with a noise canceller samples sensors in sleep for lower conversion noise. 128 KB Flash holds datalogging firmware, USB-serial stacks, and display drivers without external memory. Estimated design note: at 3.3 V and 8 MHz, active current is typically in the low-mA range per the datasheet, so duty-cycled operation extends battery life by orders of magnitude versus always-on operation.
Recommended
Building Automation and Sensor Hubs
Sensor hubs for HVAC, lighting control, and access systems benefit from the ATMEGA128L-8MN's dual USART (RS-485 field bus plus service port), TWI for digital temperature and humidity sensors, and enough Flash for BACnet-light or proprietary protocol implementations. The 64-QFN 9x9 mm package fits dense room-controller boards, while the 5 V tolerance simplifies interfacing with opto-isolated RS-485 transceivers running from the panel supply. JTAG enables boundary-scan board test as well as firmware debugging in the field fixture. Design consideration: the L-grade's fixed 8 MHz limit is generally sufficient for sensor polling loops at 100 ms periods, and the 4 KB EEPROM stores node addresses and calibration constants that survive power interruptions.
Recommended
Embedded Networking and Communication Devices
Serial-to-Ethernet bridges, gateways, and modem front-ends use the ATMEGA128L-8MN's two independent USARTs to terminate one protocol locally while forwarding another upstream, with SPI connecting external MAC/PHY or RF modules. The 128 KB Flash accommodates TCP/IP stacks, buffers, and bootloader code, and in-application self-programming permits remote firmware updates with a small boot section - a key requirement for deployed network hardware. The JTAG port accelerates stack debugging with hardware breakpoints. Performance consideration: 8 MIPS at 8 MHz suits 10/100 Mbit-attached MCUs only as a management controller, not a packet-forwarding engine, so pair it with a dedicated Ethernet controller and let the AVR handle configuration, monitoring, and serial I/O.
Recommended
Legacy ATmega128 Design Continuity
Many long-lifecycle products - agricultural controllers, marine electronics, test fixtures - were designed around the original Atmel ATmega128 and require a functionally identical part to preserve certification and firmware qualification. The ATMEGA128L-8MN is the direct continuation of that die under Microchip Technology, maintaining the 128 KB Flash / 4 KB SRAM / 4 KB EEPROM configuration, JTAG debug, and ATmega128 register map exactly. Where the -8MN grade faces allocation, the ATMEGA128L-8MUR reel variant and the 5 V ATMEGA128-16MN grade provide the same silicon in the same 64-QFN footprint. This application profile matters because firmware re-qualification for a different MCU family would cost far more than paying a modest premium for the exact legacy MPN.
Recommended
Motor Control and PWM Actuation
The ATMEGA128L-8MN's two 8-bit timers with two PWM channels each and two 16-bit timers provide up to six PWM outputs suitable for controlling DC motors, servo actuators, LED dimming channels, and heater elements. Running from 5 V, the I/O levels directly gate logic-level MOSFET drivers, while the 10-bit ADC reads current shunts and position feedback potentiometers for closed-loop control implemented in the 8 MIPS AVR core. 128 KB Flash leaves ample room for PID libraries, ramp generators, and fault-logging routines. Design consideration: verify that the 8 MHz clock resolves your required PWM frequency - a 16-bit timer at 8 MHz gives 8 kHz PWM with roughly 10-bit resolution, adequate for most heating and pumping loads but marginal for low-inductance fast servos.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA128L-8MN β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA128L-8MUR | ATMEGA128-16MN | ATMEGA1281V-8MU | ATMEGA2561-16MU |
|---|---|---|---|---|---|
| Package | 64-QFN (9x9 mm) | 64-QFN (9x9 mm) - same | 64-QFN (9x9 mm) - same | 64-QFN (9x9 mm) - same | 64-QFN (9x9 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Max Clock Speed | 8 MHz | 8 MHz | 16 MHz | 8 MHz | 16 MHz |
| Supply Voltage | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 4.5 V to 5.5 V | 1.8 V to 5.5 V | 4.5 V to 5.5 V |
| Flash Memory | 128 KB | 128 KB | 128 KB | 128 KB | 256 KB |
| SRAM | 4 KB | 4 KB | 4 KB | 8 KB | 8 KB |
| EEPROM | 4 KB | 4 KB | 4 KB | 4 KB | 4 KB |
| ATmega128 Register-Map Compatibility | Native (exact die) | Native (exact die) | Native (exact die) | Peripheral set differs - firmware review required | Peripheral set differs - firmware review required |
| Packing | Tray (MN) | Tape & Reel | Tray | Tray | Tray |
Key Differentiators
- Full legacy ATmega128 register-map compatibility (vs ATMEGA1281V-8MU)
- Low-voltage L-grade supply range (vs ATMEGA128-16MN)
- JTAG on-chip debug and boundary-scan (vs ATMEGA1281V-8MU)
- Trade-off: fixed 8 MHz clock ceiling (vs ATMEGA128-16MN)
Design Notes
The 64-QFN (9x9 mm) package has a large exposed die-attach pad on the bottom that must be soldered to a grounded copper island for mechanical reliability and thermal dissipation. Design the land pattern per the Microchip datasheet QFN footprint with via arrays (typically 5x5 or more, 0.3 mm vias) connecting the center pad to the ground plane to aid reflow wetting and heat transfer. Include fiducials and a pin-1 indicator dot alignment, since the MLF body has no visible leads to verify orientation after assembly. Inspect the center-pad solder joint via X-ray for volume production.
Decouple each VCC/AVCC pad pair with 100 nF ceramic capacitors placed within 3 mm of the pads, plus one bulk 4.7-10 uF per supply domain. Connect AVCC to VCC through a low-pass LC filter (e.g., 10 uH ferrite bead plus 100 nF/1 uF) when ADC accuracy matters - datasheet guidance is to keep AVCC within 0.3 V of VCC and never below it. Tie AREF to a clean reference through the recommended decoupling network rather than directly to AVCC when using the internal reference. The 2.7-5.5 V range tolerates Li-ion sag, but brown-out detection should be enabled via fuses at the appropriate threshold for your rail.
Three frequent ATMEGA128L-8MN pitfalls: (1) The L-grade never exceeds 8 MHz even at 5 V - do not fit a 16 MHz crystal expecting ATMEGA128-16 behavior; the two grades are separately speed-binned. (2) JTAG interface is enabled by default at reset on the shared PC pins; production firmware not using JTAG should disable the JTAGEN fuse to reclaim PC2-PC5 as general I/O. (3) The RESET pin on the QFN has no internal power-on-reset holdoff option differences from TQFP, but long PCB reset traces pick up noise - add a 10 kOhm pull-up and place the reset supervisor close to the device. Verify all fuse settings in a programming fixture before panel build.
Keep the crystal (XTAL1/XTAL2) loop compact: 8 MHz crystals need load capacitors matched to the crystal specification (commonly 12-22 pF) and guard with ground pour. Route USART0 (PE0/PE1) and USART1 away from the ADC port F traces to prevent digital coupling into 10-bit conversions; a solid ground plane under the QFN greatly reduces return-path noise. For in-circuit serial programming, keep the ISP header within 15 cm of the device or buffer the SCK/MOSI/MISO lines on larger boards.
Compliance Information
MN package suffix denotes lead-free/RoHS-compliant 64-QFN per Microchip package coding. REACH, halogen-free, and conflict-minerals status not stated in provided data - verify on the Microchip product page.
