ATMEGA128L-8MU - 8MHz AVR MCU 128KB Flash QFN-64 | Microchip
MPN: ATMEGA128L-8MU ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $19.12 | $19.12 |
| 10 | $17.21 | $172.10 |
| 100 | $15.3 | $1,530.00 |
| 500 | $13.77 | $6,885.00 |
| 1,000 | $12.39 | $12,390.00 |
ATMEGA128L-8MU Overview
An 8-bit AVR microcontroller is a Harvard-architecture RISC processor in which most of its 133 powerful instructions execute in a single clock cycle, placing it in the broader hierarchy of microcontroller units (MCUs) within the embedded processor and semiconductor family. MCUs integrate CPU, program memory, data memory, and peripherals on a single die, making them the control backbone of embedded systems.
Key features of the ATMEGA128L-8MU include 128KB (64K x 16) programmable Flash memory, 4KB SRAM, 4KB EEPROM, an 8-channel 10-bit A/D converter, and an IEEE-compatible JTAG interface for on-chip debugging and boundary-scan. It also provides two 8-bit and two 16-bit timers/counters, two USARTs, SPI, TWI (I2C-compatible), and six PWM channels, enabling compact single-chip designs.
Technically, the advanced AVR RISC architecture with a 32-register general-purpose file is directly connected to the ALU, allowing one instruction executed per clock cycle for throughput up to 8 MIPS at 8 MHz. The JTAG boundary-scan capability simplifies production test, while In-System Programmability allows firmware updates on the final PCB without removal.
Typical applications include industrial control and automation nodes, building and HVAC controllers, sensor data acquisition systems, and legacy embedded designs originally built around the pin-compatible ATmega103. The low-voltage 2.7V operation suits battery-powered instruments.
A key design consideration: when replacing an ATmega103, configure the M103C fuse so the ATmega128 boots with ATmega103-compatible behavior; consult Microchip application note on ATmega103 migration.
This page synthesizes distributor pricing, verified drop-in alternatives, pinout data, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA128L-8MU — 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-8MU (same form factor and footprint) — differing in Package, RoHS Status, Timers/Counters, ADC, Core Architecture.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA1281V-8MU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$5.92 / Unit
View Datasheet →ATMEGA1281V-8MUR
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$4.02 / Unit
View Datasheet →ATMEGA1281-16MUR
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$8.78 / Unit
View Datasheet →ATMEGA128L-8MU Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Max Clock Speed | 8 MHz |
| Program Memory (Flash) | 128KB (64K x 16) |
| SRAM | 4KB |
| EEPROM | 4KB |
| Supply Voltage | 2.7 V to 5.5 V |
| I/O Pins | 53 |
| ADC | 8-channel, 10-bit |
| Debug Interface | JTAG (on-chip debugging, boundary scan) |
| Instructions | 133 (most single-cycle) |
| Package | 64-QFN / MLF (9 x 9 mm) |
| Mounting Type | Surface Mount |
| Operating Temperature | Industrial (-40C to +85C) |
| Series | AVR ATmega |
| RoHS Status | Compliant (GREEN per FindIC listing) |
| Lifecycle Stage | Active |
ATMEGA128L-8MU Pin Configuration
| Pin 1 | PEN — Programming Enable (serial program and debug) |
| Pin 2 | PE0 (RXD0/PDI) — USART0 receive / programming data in |
| Pin 3 | PE1 (TXD0/PDO) — USART0 transmit / programming data out |
| Pin 4 | PE2 (XCK0/AIN0) — USART0 clock / analog comparator input 0 |
| Pin 5 | PE3 (OC3A/AIN1) — Timer3 output compare A / comparator input 1 |
| Pin 6 | PE4 (OC3B/INT4) — Timer3 output compare B / external interrupt 4 |
| Pin 7 | PE5 (OC3C/INT5) — Timer3 output compare C / external interrupt 5 |
| Pin 8 | PE6 (T3/INT6) — Timer3 clock input / external interrupt 6 |
| Pin 9 | PE7 (ICP3/INT7) — Timer3 input capture / external interrupt 7 |
| Pin 10 | PB0 (SS) — SPI slave select / general I/O |
| Pin 11 | PB1 (SCK) — SPI clock / general I/O |
| Pin 12 | PB2 (MOSI) — SPI master data out / general I/O |
| Pin 13 | PB3 (MISO) — SPI master data in / general I/O |
| Pin 14 | PB4 (OC0) — Timer0 output compare / PWM |
| Pin 15 | PB5 (OC1A) — Timer1 output compare A / PWM |
| Pin 16 | PB6 (OC1B) — Timer1 output compare B / PWM |
| Pin 17 | PB7 (OC2/OC1C) — Timer2 output compare / Timer1 output compare C |
| Pin 18 | PG3 (TOSC2) — Timer oscillator output (32 kHz RTC crystal) |
| Pin 19 | PG4 (TOSC1) — Timer oscillator input (32 kHz RTC crystal) |
| Pin 20 | RESET — Reset input (active low) |
| Pin 21 | VCC — Digital supply voltage |
| Pin 22 | GND — Digital ground |
| Pin 23 | XTAL2 — System crystal oscillator output |
| Pin 24 | XTAL1 — System crystal oscillator input |
| Pin 25 | PD0 (SCL/INT0) — TWI clock / external interrupt 0 |
| Pin 26 | PD1 (SDA/INT1) — TWI data / external interrupt 1 |
| Pin 27 | PD2 (RXD1/INT2) — USART1 receive / external interrupt 2 |
| Pin 28 | PD3 (TXD1/INT3) — USART1 transmit / external interrupt 3 |
| Pin 29 | PD4 (ICP1) — Timer1 input capture |
| Pin 30 | PD5 (XCK1) — USART1 external clock |
| Pin 31 | PD6 (T1) — Timer1 external counter input |
| Pin 32 | PD7 (T2) — Timer2 external counter input |
| Pin 33 | PG0 (WR) — External memory write strobe |
| Pin 34 | PG1 (RD) — External memory read strobe |
| Pin 35 | PC0 (A8) — External memory address line 8 / general I/O |
| Pin 36 | PC1 (A9) — External memory address line 9 / general I/O |
| Pin 37 | PC2 (A10) — External memory address line 10 / general I/O |
| Pin 38 | PC3 (A11) — External memory address line 11 / general I/O |
| Pin 39 | PC4 (A12) — External memory address line 12 / general I/O |
| Pin 40 | PC5 (A13) — External memory address line 13 / general I/O |
| Pin 41 | PC6 (A14) — External memory address line 14 / general I/O |
| Pin 42 | PC7 (A15) — External memory address line 15 / general I/O |
| Pin 43 | PG2 (ALE) — External memory address latch enable |
| Pin 44 | PA7 (AD7) — External memory address/data line 7 / general I/O |
| Pin 45 | PA6 (AD6) — External memory address/data line 6 / general I/O |
| Pin 46 | PA5 (AD5) — External memory address/data line 5 / general I/O |
| Pin 47 | PA4 (AD4) — External memory address/data line 4 / general I/O |
| Pin 48 | PA3 (AD3) — External memory address/data line 3 / general I/O |
| Pin 49 | PA2 (AD2) — External memory address/data line 2 / general I/O |
| Pin 50 | PA1 (AD1) — External memory address/data line 1 / general I/O |
| Pin 51 | PA0 (AD0) — External memory address/data line 0 / general I/O |
| Pin 52 | VCC — Digital supply voltage |
| Pin 53 | GND — Digital ground |
| Pin 54 | PF0 (ADC0) — ADC input 0 / general I/O |
| Pin 55 | PF1 (ADC1) — ADC input 1 / general I/O |
| Pin 56 | PF2 (ADC2) — ADC input 2 / general I/O |
| Pin 57 | PF3 (ADC3) — ADC input 3 / general I/O |
| Pin 58 | PF4 (ADC4/TCK) — ADC input 4 / JTAG test clock |
| Pin 59 | PF5 (ADC5/TMS) — ADC input 5 / JTAG test mode select |
| Pin 60 | PF6 (ADC6/TDO) — ADC input 6 / JTAG test data out |
| Pin 61 | PF7 (ADC7/TDI) — ADC input 7 / JTAG test data in |
| Pin 62 | AREF — ADC analog reference voltage |
| Pin 63 | AGND — Analog ground |
| Pin 64 | AVCC — ADC supply voltage |
Typical Applications
ATMEGA128L-8MU is suitable for 6 applications: Industrial Control and Automation, Battery-Powered Instrumentation, Building Automation and HVAC Controllers, Legacy ATmega103 System Migration, Sensor Data Acquisition Systems, Embedded Robotics and Motor Control.
Industrial Control and Automation
The ATMEGA128L-8MU fits industrial control nodes because it combines 53 I/O lines, dual USARTs for Modbus RTU linking, SPI/TWI for field sensors, and a 10-bit ADC with 8 multiplexed channels for analog process signals. Operating from a 2.7V to 5.5V supply lets it run directly from a 5V industrial rail, and the industrial temperature grade of -40C to +85C withstands cabinet environments. The JTAG boundary-scan interface accelerates production test of assembled control boards. Placed as the main controller, its 8 MHz core delivers roughly 8 MIPS, sufficient for relay sequencing, PID loops at moderate rates, and protocol handling, while the 4KB EEPROM stores calibration and configuration data that must survive power cycles.
Recommended
Battery-Powered Instrumentation
With its 'L' low-voltage grade rated 2.7V to 5.5V, the ATMEGA128L-8MU runs directly from a 3.0V lithium cell without a boost regulator, and AVR sleep modes (idle, power-down, power-save) cut current to microamp levels between measurements. The 8-channel 10-bit ADC digitizes sensor inputs, and the 4KB EEPROM retains zero/span calibration without battery backup. The 64-QFN 9x9 mm package suits compact handheld enclosures, and 53 I/O lines drive displays, keypads, and actuators. A typical design wakes the MCU on an external interrupt, samples the ADC array, logs to EEPROM or external flash over SPI, and returns to power-down, maximizing battery life in data loggers and portable meters.
Recommended
Building Automation and HVAC Controllers
The ATMEGA128L-8MU is a proven fit for building automation panels: dual USARTs handle BACnet/Modbus links, TWI (I2C) reads temperature and humidity sensors, and six PWM channels drive damper motors and heater triacs. The 8 MHz AVR core comfortably runs a multi-loop PID scheduler with 8 MIPS single-cycle throughput, while 128KB Flash accommodates protocol stacks and web- bootloader firmware for field updates over the network. The industrial temperature rating supports rooftop and mechanical-room installations, and the JTAG interface enables boundary-scan test of assembled controller boards. The 4KB EEPROM stores setpoints and schedules that persist through power interruptions without external memory.
Recommended
Legacy ATmega103 System Migration
Microchip positions the ATmega128 as the direct migration device for the discontinued ATmega103: it is 100% pin compatible and can replace the ATmega103 on existing PCBs. Engineers program the M103C compatibility fuse so the ATMEGA128L-8MU boots with ATmega103 behavior, then follow the Microchip application note 'Replacing ATmega103 by ATmega128' for register and SRAM-mapping caveats. The low-voltage L grade matches the 3.3V supplies common on ATmega103 boards, and the 64-QFN/MLF package mirrors the original footprint. This path extends product lifetimes with zero PCB redesign while gaining 128KB Flash and JTAG debug that the ATmega103 lacked.
Recommended
Sensor Data Acquisition Systems
For distributed data acquisition, the ATMEGA128L-8MU offers an 8-channel 10-bit ADC with internal reference and oversampling capability, letting one MCU digitize eight analog sensors at up to roughly 15 kSPS effective rate. SPI connects high-speed external ADCs or precision converters when 10-bit resolution is insufficient, while TWI supports low-rate digital sensors on a shared bus. Dual USARTs stream measurements to both a local HMI and a remote radio or gateway simultaneously. Its 2.7V to 5.5V supply and industrial temperature range suit unattended field installations, and power-down sleep between sampling windows keeps average drain compatible with battery or energy-harvesting power budgets in remote monitoring networks.
Recommended
Embedded Robotics and Motor Control
Robotics controllers benefit from the ATMEGA128L-8MU's six PWM channels, four timers, and rich I/O: PWM outputs drive H-bridge gates for DC motor speed control, quadrature encoders feed external-interrupt and timer-capture inputs, and SPI manages an IMU at kilohertz rates. The 8 MHz single-cycle AVR core executes a 1 kHz control loop with headroom for PID per axis, while 128KB Flash holds trajectory tables and communication stacks (Bluetooth or serial telemetry on either USART). Operating from a 5V rail shared with servos simplifies power design, and 53 GPIO lines interface sonar arrays, limit switches, and status LEDs on a single controller board.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA128L-8MU — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA1281V-8MU | ATMEGA1281V-8MUR | ATMEGA1281-16MUR |
|---|---|---|---|---|
| Package | 64-QFN / MLF (9x9 mm) | 64-QFN / MLF (9x9 mm) - same | 64-QFN / MLF (9x9 mm) - same | 64-QFN / MLF (9x9 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Max Clock Speed | 8 MHz | 8 MHz | 8 MHz | 16 MHz |
| Flash Memory | 128KB | 128KB | 128KB | 128KB |
| SRAM | 4KB | 8KB | 8KB | 8KB |
| Supply Voltage | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 4.5 V to 5.5 V |
| I/O Pins | 53 | 54 | 54 | 54 |
| Special Features | JTAG, 2 USART, SPI, TWI | JTAG, AES crypto module, PSC | JTAG, AES crypto module, PSC | JTAG, AES crypto module, PSC |
Key Differentiators
- ATmega103 legacy compatibility with true pin compatibility (vs ATMEGA1281V-8MU)
- Wider low-voltage range than the 16 MHz sibling (vs ATMEGA1281-16MUR)
- Lower SRAM than the migration family (vs ATMEGA1281V-8MU)
Design Notes
The 64-QFN/MLF package has a large exposed die pad on the underside that must be soldered to a grounded copper pour on the PCB for both thermal dissipation and mechanical reliability. The MLF (Micro Lead Frame) package is not a leaded QFN: perimeter pads are under the body edge, so specify a 0.5 mm-pitch land pattern with via fencing to ground. Inspect with X-ray or use sufficient stencil aperture design, since perimeter joints are not optically visible after reflow.
Decouple AVCC separately from VCC with an RC low-pass filter (e.g., 10 uH inductor or 100 ohm resistor plus 100 nF capacitor) to keep ADC noise low; connect AREF through a 100 nF capacitor to AGND and never drive it while the internal reference is selected. Place 100 nF ceramic capacitors at both VCC pins (21 and 52) as close to the pins as possible. At 8 MHz the current draw is modest, but brown-out detection should be enabled via fuse for 3.3V battery systems.
Two frequent traps: first, when migrating from ATmega103, the M103C fuse must be cleared to enable the full ATmega128 feature set (extended I/O map and added SRAM); second, the JTAG interface shares port F ADC pins 4-7, and JTAG stays enabled by default - either disable via the JTD bit or JTAGEN fuse, or ADC channels 4-7 will not work. Also remember that the 'MU' (MLF) and 'AU' (TQFP) suffixes have different land patterns and are not footprint interchangeable.
Compliance Information
FindIC lists the ATMEGA128L-8MU as GREEN (Microchip RoHS-compliant, halogen-free packaging). REACH and conflict-minerals declarations not present in provided data.
