ATMEGA128L-8AU - 8MHz 128KB Flash AVR MCU | Microchip
MPN: ATMEGA128L-8AU β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $35.78 | $35.78 |
| 10 | $32.2 | $322.00 |
| 100 | $29 | $2,900.00 |
| 500 | $26.1 | $13,050.00 |
| 1,000 | $23.49 | $23,490.00 |
ATMEGA128L-8AU Overview
An 8-bit microcontroller is a complete computer system on a single chip, integrating a processor core, program memory, data memory, and peripherals such as timers, UARTs, and ADCs. Within the power-management hierarchy of embedded systems, the MCU sits at the heart of the control layer, executing user firmware that sequences sensors, actuators, and communication interfaces. The AVR ATmega family is a Harvard-architecture RISC line now manufactured and supported by Microchip Technology following its acquisition of Atmel Corporation.
Key features of the ATMEGA128L-8AU include 133 powerful instructions, most executable in a single clock cycle, delivering throughput approaching 1 MIPS per MHz. The 8-channel 10-bit ADC supports analog sensing, while the built-in JTAG interface enables on-chip debugging and boundary-scan testing. The L-8 speed-voltage grade guarantees operation across the full 2.7V to 5.5V industrial range at 8 MHz, and six low-power sleep modes reduce standby consumption for battery-operated products.
Architecturally, the device pairs the AVR enhanced RISC core with 32 general-purpose working registers directly connected to the ALU, allowing two independent registers to be accessed in one instruction executed in one clock cycle. Memory is organized as 128KB of ISP Flash with optional boot-code section for in-application programming, plus 4KB EEPROM for nonvolatile parameter storage and 4KB internal SRAM, expandable via the external memory interface on Ports A and C.
Typical applications include industrial automation and control panels, battery-powered data loggers and metering systems, and embedded communication nodes using the dual hardware USARTs, SPI, and two-wire (I2C-compatible) interfaces. The JTAG debugger makes it equally suitable for long-lifetime products requiring in-circuit field updates.
A key design consideration is clock selection: at 8 MHz the ATmega128L reaches its speed limit across the full voltage range, so use the internal calibrated RC oscillator or a conservative external crystal, and confirm fuse settings (CKOPT, BODLEVEL) before production programming.
This page synthesizes distributor pricing, pin-compatible drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA128L-8AU 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-8AU (same form factor and footprint) β differing in Flash Memory, Operating Temperature, Supply Voltage Range, Timers/Counters, EEPROM.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA128L-8AJ
β Drop-Inβ In Stock
$8.7 / Unit
View Datasheet βATMEGA128L-8AI
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA128-16AI
β Drop-Inβ In Stock
$5.9 / Unit
View Datasheet βATMEGA1281-16AUR
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA1281V-8AUR
β Drop-Inβ In Stock
$4.4 / Unit
View Datasheet βATMEGA128L-8AU Maximum Ratings & Electrical Characteristics
| Core Architecture | AVR 8-bit RISC |
| Max Clock Frequency | 8 MHz |
| Flash Memory | 128 KB (64K x 16) |
| EEPROM | 4 KB |
| SRAM | 4 KB |
| Supply Voltage Range | 2.7 V to 5.5 V |
| I/O Pins | 53 |
| ADC Resolution | 10-bit, 8 channels |
| USARTs | 2 |
| Timers/Counters | 2 x 8-bit, 2 x 16-bit |
| Debug Interface | JTAG (on-chip debug + boundary scan) |
| MIPS | Up to 8 MIPS at 8 MHz (1 MIPS/MHz) |
| Package | 64-TQFP (14x14 mm) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C (industrial) |
| Low-Power Sleep Modes | 6 modes |
| In-System Programming | Yes (ISP via SPI) |
| RoHS Status | Compliant |
ATMEGA128L-8AU Pin Configuration
| Pin 1 | PEN β Programming Enable (used during programming mode) |
| Pin 2 | PE0 β Port E bit 0 / RXD0 (USART0 receive) |
| Pin 3 | PE1 β Port E bit 1 / TXD0 (USART0 transmit) |
| Pin 4 | PE2 β Port E bit 2 / XCK0 / AIN0 |
| Pin 5 | PE3 β Port E bit 3 / OC3A / AIN1 |
| Pin 6 | PE4 β Port E bit 4 / OC3B / INT4 |
| Pin 7 | PE5 β Port E bit 5 / OC3C / INT5 |
| Pin 8 | PE6 β Port E bit 6 / T3 / INT6 |
| Pin 9 | PE7 β Port E bit 7 / ICP3 / INT7 / CLKO |
| Pin 10 | PB0 β Port B bit 0 / SS (SPI slave select) |
| Pin 11 | PB1 β Port B bit 1 / SCK (SPI clock) |
| Pin 12 | PB2 β Port B bit 2 / MOSI (SPI data out) |
| Pin 13 | PB3 β Port B bit 3 / MISO (SPI data in) |
| Pin 14 | PB4 β Port B bit 4 / OC0 (Timer0 PWM output) |
| Pin 15 | PB5 β Port B bit 5 / OC1A (Timer1 PWM output A) |
| Pin 16 | PB6 β Port B bit 6 / OC1B (Timer1 PWM output B) |
| Pin 17 | PB7 β Port B bit 7 / OC2 / OC1C (Timer2/Timer1C PWM output) |
| Pin 18 | PG0 β Port G bit 0 / WR (external memory write strobe) |
| Pin 19 | PG1 β Port G bit 1 / RD (external memory read strobe) |
| Pin 20 | PC0 β Port C bit 0 / A8 (external memory address) |
| Pin 21 | PC1 β Port C bit 1 / A9 |
| Pin 22 | PC2 β Port C bit 2 / A10 |
| Pin 23 | PC3 β Port C bit 3 / A11 |
| Pin 24 | PC4 β Port C bit 4 / A12 |
| Pin 25 | PC5 β Port C bit 5 / A13 |
| Pin 26 | PC6 β Port C bit 6 / A14 |
| Pin 27 | PC7 β Port C bit 7 / A15 |
| Pin 28 | VCC β Digital supply voltage |
| Pin 29 | GND β Ground |
| Pin 30 | PA7 β Port A bit 7 / AD7 (external memory address/data) |
| Pin 31 | PA6 β Port A bit 6 / AD6 |
| Pin 32 | PA5 β Port A bit 5 / AD5 |
| Pin 33 | PA4 β Port A bit 4 / AD4 |
| Pin 34 | PA3 β Port A bit 3 / AD3 |
| Pin 35 | PA2 β Port A bit 2 / AD2 |
| Pin 36 | PA1 β Port A bit 1 / AD1 |
| Pin 37 | PA0 β Port A bit 0 / AD0 |
| Pin 38 | PF0 β Port F bit 0 / ADC0 (analog input) |
| Pin 39 | PF1 β Port F bit 1 / ADC1 |
| Pin 40 | PF2 β Port F bit 2 / ADC2 |
| Pin 41 | PF3 β Port F bit 3 / ADC3 |
| Pin 42 | PF4 β Port F bit 4 / ADC4 / TCK (JTAG clock) |
| Pin 43 | PF5 β Port F bit 5 / ADC5 / TMS (JTAG mode select) |
| Pin 44 | PF6 β Port F bit 6 / ADC6 / TDO (JTAG data out) |
| Pin 45 | PF7 β Port F bit 7 / ADC7 / TDI (JTAG data in) |
| Pin 46 | GND β Ground |
| Pin 47 | AREF β Analog reference voltage for ADC |
| Pin 48 | AVCC β Analog supply voltage for ADC (connect to VCC via filter) |
| Pin 49 | PG2 β Port G bit 2 / ALE (external memory address latch enable) |
| Pin 50 | PG3 β Port G bit 3 / TOSC2 (Timer2 oscillator output) |
| Pin 51 | PG4 β Port G bit 4 / TOSC1 (Timer2 oscillator input) |
| Pin 52 | XTAL1 β Main system clock oscillator input |
| Pin 53 | XTAL2 β Main system clock oscillator output |
| Pin 54 | RESET β Reset input (active low, internal pull-up) |
| Pin 55 | PD0 β Port D bit 0 / RXD1 / INT0 (USART1 receive, external interrupt 0) |
| Pin 56 | PD1 β Port D bit 1 / TXD1 / INT1 (USART1 transmit, external interrupt 1) |
| Pin 57 | PD2 β Port D bit 2 / INT2 / SDA (two-wire data) |
| Pin 58 | PD3 β Port D bit 3 / INT3 / SCL (two-wire clock) |
| Pin 59 | PD4 β Port D bit 4 / ICP1 (Timer1 input capture) |
| Pin 60 | PD5 β Port D bit 5 / XCK1 (USART1 clock) |
| Pin 61 | PD6 β Port D bit 6 / T1 (Timer1 external clock) |
| Pin 62 | PD7 β Port D bit 7 / T0 (Timer0 external clock) |
| Pin 63 | VCC β Digital supply voltage |
| Pin 64 | GND β Ground |
Typical Applications
ATMEGA128L-8AU is suitable for 6 applications: Industrial Automation and Control, Battery-Powered Data Loggers, Embedded Communication Nodes, Sensor Measurement and Data Acquisition, Legacy Atmel Design Maintenance, IoT and Smart Home Edge Devices.
Industrial Automation and Control
The ATMEGA128L-8AU fits industrial control panels and machine controllers because it combines 53 I/O lines with an external memory interface that can expand beyond the internal 4KB SRAM, all in a -40C to +85C industrial TQFP-64 package. Its dual USARTs, SPI, and TWI (I2C) interfaces talk natively to motor drivers, PLC I/O expanders, and HMI displays, while the JTAG port supports field servicing. Firmware runs from 128KB ISP Flash with a boot section for in-application updates over RS-485, avoiding recalls when protocols change. The 8 MHz clock is ample for sequencing and polling loops typical of factory equipment, and the 10-bit ADC reads analog sensor channels such as pressure and level transducers without an external converter.
Recommended
Battery-Powered Data Loggers
For battery-operated loggers and metering products, the ATMEGA128L-8AU offers a 2.7V low-voltage operating point and six sleep modes, cutting static and dynamic consumption for long-cycle standby designs. The AVR core executes roughly 1 MIPS per MHz, so firmware can scale the clock down or park the CPU in power-save mode between samples, waking on the asynchronous Timer2 32 kHz crystal or external interrupt. The 4KB EEPROM retains calibration constants and rolling records through battery swaps, and the 8-channel 10-bit ADC digitizes analog channels without added BOM cost. Sampling firmware, compression tables, and communications stacks all fit comfortably in 128KB Flash.
Recommended
Embedded Communication Nodes
The ATMEGA128L-8AU is well suited to Modbus RTU gateways, CAN-attached nodes, and RS-485 field devices because it provides two independent hardware USARTs, hardware SPI, and a TWI master/slave interface. The second USART isolates the service/debug port from the field bus, and the external memory interface can buffer protocol payloads beyond the internal 4KB SRAM. Bootloader firmware stored in the Flash boot section enables remote firmware update over the serial link, a standard practice in deployed node fleets. Operation from a 5V industrial rail gives generous noise margin for long cable runs, and the 8 MHz clock comfortably sustains 115.2 kbaud traffic with interrupt-driven buffering.
Recommended
Sensor Measurement and Data Acquisition
The integrated 8-channel 10-bit ADC with internal reference options makes the ATMEGA128L-8AU a compact DAQ controller for RTD bridges, strain gauges, and analog transducer arrays. Ports F and A feed the ADC directly, and AREF/AVCC on dedicated pins (47/48) allow precise reference filtering, with JTAG pins doubling as ADC4-ADC7 when debug is not required. Timer1 captures event timestamps with 16-bit resolution, so sampled channels can be correlated to time. Firmware averaging, oversampling, and per-channel calibration tables stored in the 4KB EEPROM deliver effective resolution beyond the raw 10 bits for many industrial measurement tasks.
Recommended
Legacy Atmel Design Maintenance
A large installed base of ATmega103 and ATmega128 designs continues to require production support, and the ATMEGA128L-8AU is the canonical drop-in for these sockets: the ATmega128 is 100% pin compatible with the ATmega103 and replaces it on existing PCBs, per the Microchip ATmega128 datasheet and its application note on ATmega103 replacement. For boards already laid out for the 64-TQFP ATmega128, speed-voltage and temperature suffix swaps (AJ, AI, 16-grade) let purchasing react to allocation without layout changes. The JTAG interface and ISP programming keep firmware maintainable with current Atmel-ICE and legacy JTAGICE toolchains.
Recommended
IoT and Smart Home Edge Devices
For smart-home nodes, thermostats, and access-control terminals, the ATMEGA128L-8AU drives displays, reads touch or button matrices across 53 I/O, and links to radio or Ethernet modules over SPI/UART. The 2.7V supply floor matches single lithium-cell and 3.3V designs, while sleep modes keep standby current low between wake events. The 128KB Flash accommodates protocol stacks such as MQTT-over-module firmware, and the EEPROM stores device identity and network credentials through power loss. Its industrial temperature rating also covers unconditioned spaces like garages and outdoor enclosures, where consumer-grade parts would be marginal.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA128L-8AU β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA128L-8AJ | ATMEGA128L-8AI | ATMEGA128-16AI | ATMEGA1281-16AUR | ATMEGA1281V-8AUR |
|---|---|---|---|---|---|---|
| Package | 64-TQFP (14x14 mm) | 64-TQFP (14x14 mm) - same | PQFP64 - same footprint | 64-TQFP (14x14 mm) - same | 64-TQFP (14x14 mm) - same | 64-TQFP (14x14 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Max Clock Frequency | 8 MHz | 8 MHz | 8 MHz | 16 MHz | 16 MHz | 8 MHz |
| Supply Voltage Range | 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 (full speed) | 4.5 V to 5.5 V (full speed) | 1.8 V to 5.5 V |
| Flash Memory | 128 KB | 128 KB | 128 KB | 128 KB | 128 KB | 128 KB |
| SRAM | 4 KB | 4 KB | 4 KB | 4 KB | 8 KB | 8 KB |
| Operating Temperature | -40C to +85C (industrial) | 0C to +70C (commercial) | -40C to +85C (industrial) | -40C to +85C (industrial) | -40C to +85C (industrial) | -40C to +85C (industrial) |
| JTAG Debug / Boundary Scan | Yes | Yes | Yes | Yes | Yes (debugWIRE/JTAG per family) | Yes (debugWIRE/JTAG per family) |
| I/O Pins | 53 | 53 | 53 | 53 | 54 | 54 |
Key Differentiators
- Full-voltage-range low-voltage operation (vs ATMEGA128-16AI)
- Industrial temperature rating for field equipment (vs ATMEGA128L-8AJ)
- Doubling of SRAM without footprint change (vs ATMEGA1281-16AUR)
Design Notes
Connect AVCC (pin 48) to VCC through a low-pass LC filter (for example a 10 uH inductor or ferrite bead with 100 nF and 10 uF capacitors to ground) even if the ADC is unused; the datasheet requires AVCC within 0.3V of VCC for correct operation. Tie AREF (pin 47) to a decoupled reference with a 100 nF capacitor and never drive it directly from a low-impedance source without a series resistor. Enable brown-out detection via fuse (BODLEVEL) at approximately 2.7V for L-grade parts to prevent EEPROM corruption during supply droop.
The 64-TQFP (14x14 mm) exposed leadframe needs no thermal pad, but provide solid ground pour under the die area with at least 12 to 16 vias to the ground plane to reduce ground bounce across the four GND pins (29, 46, 64 plus internal paddle bond). Place 100 nF ceramic decoupling capacitors within 3 mm of VCC pins 28 and 63. Keep the JTAG header (PF4-PF7) traces short if in-circuit debug will be used in production, and add a 10 kN pull-up on RESET (pin 54) for reliable external reset drive.
The most common bring-up failure is incorrect fuse configuration: enabling external crystal clock fuses without a working crystal bricks ISP access, so verify CKOPT and SUT/CKSEL settings against the datasheet clock table before programming, and always test with a known-good programmer that supports high-voltage parallel recovery (PEN pin 1 mode). Second, remember that the L-8 grade guarantees 8 MHz only across the full 2.7-5.5V range; do not overclock above 8 MHz at 3.3V. Third, when replacing an ATmega103, follow the Microchip application note on ATmega103 replacement because register and fuse maps differ.
Compliance Information
AU suffix denotes lead-free/RoHS-compliant 64-TQFP per DigiKey/Mouser/LCSC listings. REACH and halogen-free declarations not stated in the provided data.
