ATMEGA64L-8AJ - 8MHz 64KB Flash AVR MCU | Microchip
MPN: ATMEGA64L-8AJ ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.42 | $7.42 |
| 10 | $6.68 | $66.80 |
| 100 | $5.92 | $592.00 |
| 500 | $5.31 | $2,655.00 |
| 1,000 | $4.75 | $4,750.00 |
ATMEGA64L-8AJ Overview
An AVR microcontroller is an 8-bit reduced-instruction-set (RISC) MCU built around a Harvard architecture that executes most instructions in a single clock cycle, placing it in the embedded microcontroller tier of the semiconductor hierarchy: microcontroller -> integrated circuit -> semiconductor. AVR MCUs from Microchip Technology are widely used in industrial control, consumer devices, and automotive sub-systems.
Key features include 64KB self-programmable Flash with a separate boot lock section, 53 general-purpose I/O lines, and rich peripherals: two 8-bit timers, two 16-bit timers, an 8-channel 10-bit ADC, two UART/USART ports, SPI, and I2C (TWI) interfaces. JTAG boundary scan and on-chip debug simplify development and production testing.
The AVR core achieves close to 1 MIPS per MHz throughput, so the 8MHz ATmega64L delivers roughly 8 MIPS while consuming low quiescent power, with six software-selectable sleep modes for battery-operated designs. The external memory interface expands addressable SRAM beyond the internal 4KB, and a full-duplex UART plus master/slave SPI support multi-chip systems.
Typical applications include industrial automation controllers, HVAC and building management panels, data loggers, and 5V legacy board upgrades where the 100% pin-compatible replacement of ATmega103 is exploited.
Design consideration: keep the L-grade 8MHz frequency limit in mind - if your firmware needs more than 8MHz at 5V, select the ATMEGA64-16AU 16MHz variant on the same footprint.
This page synthesizes distributor availability, drop-in alternatives, pinout, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA64L-8AJ — 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 ATMEGA64L-8AJ (same form factor and footprint) — differing in Package, ADC, EEPROM, Operating Temperature, Program Memory Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA64L-8AU
✅ Drop-In✓ In Stock
$4.55 / Unit
View Datasheet →ATMEGA64L-8AI
✅ Drop-In✓ In Stock
$6.7 / Unit
View Datasheet →ATMEGA64A-AUR
✅ Drop-In✓ In Stock
$4.1 / Unit
View Datasheet →ATMEGA64-16AU
✅ Drop-In✓ In Stock
$7.23 / Unit
View Datasheet →ATMEGA103-6AC
✅ Drop-In✓ In Stock
$8.2 / Unit
View Datasheet →ATMEGA64L-8AJ Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Program Memory (Flash) | 64KB (32K x 16) |
| SRAM | 4KB |
| EEPROM | 2KB |
| Maximum Clock Speed | 8MHz |
| Supply Voltage | 2.7V to 5.5V |
| Data Bus Width | 8 bit |
| I/O Ports | 53 I/O lines |
| ADC | 8-channel 10-bit |
| Communication Interfaces | I2C (TWI), SPI, 2x UART/USART |
| Timers | 2x 8-bit, 2x 16-bit |
| Package | 64-TQFP (14x14 mm) |
| Mounting Type | Surface Mount |
| On-Chip Debug | JTAG (IEEE 1149.1) |
| External Memory Interface | Yes (expandable SRAM) |
| Lifecycle Stage | ACTIVE |
| Approximate Throughput | Up to 8 MIPS at 8MHz |
ATMEGA64L-8AJ Pin Configuration
| Pin 1 | PEN — Programming Enable (high-voltage parallel programming) |
| Pin 2 | PB0/SS — Port B bit 0 / SPI Slave Select |
| Pin 3 | PB1/SCK — Port B bit 1 / SPI Serial Clock |
| Pin 4 | PB2/MOSI — Port B bit 2 / SPI Master Output |
| Pin 5 | PB3/MISO — Port B bit 3 / SPI Master Input |
| Pin 6 | PB4/OC0 — Port B bit 4 / Timer0 Output Compare |
| Pin 7 | PB5/OC1A — Port B bit 5 / Timer1 Output Compare A |
| Pin 8 | PB6/OC1B — Port B bit 6 / Timer1 Output Compare B |
| Pin 9 | PB7/OC2 — Port B bit 7 / Timer2 Output Compare |
| Pin 10 | RESET — Active-low reset input |
| Pin 11 | VCC — Digital supply voltage |
| Pin 12 | GND — Ground |
| Pin 13 | XTAL2 — Crystal oscillator output |
| Pin 14 | XTAL1 — Crystal oscillator input / external clock |
| Pin 15 | PD0/SCL/INT0 — Port D bit 0 / TWI SCL / External Interrupt 0 |
| Pin 16 | PD1/SDA/INT1 — Port D bit 1 / TWI SDA / External Interrupt 1 |
| Pin 17 | PD2/RXD1 — Port D bit 2 / USART1 receive |
| Pin 18 | PD3/TXD1 — Port D bit 3 / USART1 transmit |
| Pin 19 | PD4/IC1 — Port D bit 4 / Timer1 Input Capture |
| Pin 20 | PD5/XCK1 — Port D bit 5 / USART1 external clock |
| Pin 21 | PD6/T1 — Port D bit 6 / Timer1 external counter |
| Pin 22 | PD7/T2 — Port D bit 7 / Timer2 external counter |
| Pin 23 | PE0/RXD0 — Port E bit 0 / USART0 receive |
| Pin 24 | PE1/TXD0 — Port E bit 1 / USART0 transmit |
| Pin 25 | PE2/AIN0 — Port E bit 2 / Analog Comparator positive input |
| Pin 26 | PE3/AIN1 — Port E bit 3 / Analog Comparator negative input |
| Pin 27 | PE4/OC3B/INT4 — Port E bit 4 / Timer3 Output Compare B / INT4 |
| Pin 28 | PE5/OC3C/INT5 — Port E bit 5 / Timer3 Output Compare C / INT5 |
| Pin 29 | PE6/T3/INT6 — Port E bit 6 / Timer3 clock / INT6 |
| Pin 30 | PE7/ICP3/INT7 — Port E bit 7 / Timer3 Input Capture / INT7 |
| Pin 31 | VCC — Digital supply voltage |
| Pin 32 | GND — Ground |
| Pin 33 | PF0/ADC0 — Port F bit 0 / ADC channel 0 |
| Pin 34 | PF1/ADC1 — Port F bit 1 / ADC channel 1 |
| Pin 35 | PF2/ADC2 — Port F bit 2 / ADC channel 2 |
| Pin 36 | PF3/ADC3 — Port F bit 3 / ADC channel 3 |
| Pin 37 | PF4/ADC4/TCK — Port F bit 4 / ADC channel 4 / JTAG TCK |
| Pin 38 | PF5/ADC5/TMS — Port F bit 5 / ADC channel 5 / JTAG TMS |
| Pin 39 | PF6/ADC6/TDO — Port F bit 6 / ADC channel 6 / JTAG TDO |
| Pin 40 | PF7/ADC7/TDI — Port F bit 7 / ADC channel 7 / JTAG TDI |
| Pin 41 | PG0/WR — Port G bit 0 / External memory write strobe |
| Pin 42 | PG1/RD — Port G bit 1 / External memory read strobe |
| Pin 43 | PC0/A8 — Port C bit 0 / External memory address bit 8 |
| Pin 44 | PC1/A9 — Port C bit 1 / External memory address bit 9 |
| Pin 45 | PC2/A10 — Port C bit 2 / External memory address bit 10 |
| Pin 46 | PC3/A11 — Port C bit 3 / External memory address bit 11 |
| Pin 47 | PC4/A12 — Port C bit 4 / External memory address bit 12 |
| Pin 48 | PC5/A13 — Port C bit 5 / External memory address bit 13 |
| Pin 49 | PC6/A14 — Port C bit 6 / External memory address bit 14 |
| Pin 50 | PC7/A15 — Port C bit 7 / External memory address bit 15 |
| Pin 51 | GND — Ground |
| Pin 52 | VCC — Digital supply voltage |
| Pin 53 | PA0/AD0 — Port A bit 0 / External memory address/data bit 0 |
| Pin 54 | PA1/AD1 — Port A bit 1 / External memory address/data bit 1 |
| Pin 55 | PA2/AD2 — Port A bit 2 / External memory address/data bit 2 |
| Pin 56 | PA3/AD3 — Port A bit 3 / External memory address/data bit 3 |
| Pin 57 | PA4/AD4 — Port A bit 4 / External memory address/data bit 4 |
| Pin 58 | PA5/AD5 — Port A bit 5 / External memory address/data bit 5 |
| Pin 59 | PA6/AD6 — Port A bit 6 / External memory address/data bit 6 |
| Pin 60 | PA7/AD7 — Port A bit 7 / External memory address/data bit 7 |
| Pin 61 | AREF — ADC analog reference input |
| Pin 62 | AVCC — Analog supply for ADC and Port F |
| Pin 63 | AGND — Analog ground |
| Pin 64 | PG2/ALE — Port G bit 2 / External memory address latch enable |
Typical Applications
ATMEGA64L-8AJ is suitable for 6 applications: Industrial Automation Controllers, HVAC and Building Management Panels, Battery-Powered Data Loggers, Legacy ATmega103 Board Maintenance, Multi-Protocol Communication Nodes, 5V Legacy Board Upgrades and Retrofits.
Industrial Automation Controllers
The ATMEGA64L-8AJ fits industrial automation controllers because its 64KB Flash stores complex state machines and communication stacks, while 53 I/O lines drive relays, indicators, and keypads directly. The dual full-duplex UART/USART ports enable simultaneous Modbus RTU slave and diagnostic links, and the I2C/SPI interfaces connect RTCs and EEPROM for configuration storage. Operating from 2.7V to 5.5V, the part integrates cleanly on legacy 5V control boards. JTAG boundary-scan supports production test on densely populated boards, and the external memory interface expands beyond 4KB SRAM when data buffering grows, all at roughly 8 MIPS throughput.
Recommended
HVAC and Building Management Panels
Building management and HVAC control panels benefit from the ATMEGA64L-8AJ's 8-channel 10-bit ADC, which digitizes up to eight temperature, humidity, or pressure sensor inputs without an external converter. The 2KB EEPROM preserves setpoints and schedules across power cycles, and the TWI (I2C) interface chains multiple peripheral devices on a two-wire bus. The 8MHz L-grade device runs cool and supports sleep modes between polling cycles, reducing average power in always-on installations. UART connectivity reports status to a supervisor network, while the 64KB Flash holds menus, fonts, and schedule tables for local operator interfaces on 5V panels.
Recommended
Battery-Powered Data Loggers
For battery-powered data loggers, the ATMEGA64L-8AJ combines six software-selectable sleep modes with 2.7V operation, extending battery life in field instruments that sample for months. The 8-channel 10-bit ADC captures multi-sensor analog inputs, and the external memory interface addresses external SRAM beyond the internal 4KB for long recording sessions. SPI handles fast serial flash or SD-card style storage, while one UART streams logged data to a PC during retrieval. The 64KB Flash reserves boot-section space for firmware updates in the field via the self-programming bootloader, eliminating recalls when calibration or logging logic changes are required after deployment.
Recommended
Legacy ATmega103 Board Maintenance
The ATmega64 is, per Microchip's datasheet, 100% pin compatible with ATmega103 and can replace it on current printed circuit boards, making ATMEGA64L-8AJ the standard migration device for maintaining legacy ATmega103-based equipment. As ATmega103 becomes scarce, production lines solder ATmega64 into the existing TQFP-64 footprint with no PCB change. The migration application notes document the register-level differences that firmware must absorb, typically small peripheral initialization changes. Hardware compatibility preserves tooling, fixtures, and validation investment. The 2.7V to 5.5V L-grade supply range covers both the original 5V boards and any 3.3V derivatives in the same product family.
Recommended
Multi-Protocol Communication Nodes
Communication nodes benefit from the ATMEGA64L-8AJ's two independent UART/USART ports, which allow simultaneous operation of, for example, a Modbus or proprietary field bus on one port and a service console on the other. SPI and TWI add local expansion to port expanders, ADCs, and displays, so a single MCU can bridge field wiring and a local touch interface. The external bus interface (ALE/RD/WR with multiplexed address-data ports) offloads memory-hungry protocol buffers to external SRAM. At 8MHz the AVR core delivers roughly 8 MIPS, sufficient for interrupt-driven framing, checksum computation, and packet routing at field-bus data rates while leaving headroom in the 64KB Flash.
Recommended
5V Legacy Board Upgrades and Retrofits
Many industrial products in the field remain 5V designs, and the ATMEGA64L-8AJ is a natural fit for these retrofits because the L grade tolerates 5V while also accepting 3.3V, giving one BOM part across board revisions. The 64-TQFP (14x14 mm) footprint is mechanically robust for wave and selective soldering processes common in repair shops. The 2KB EEPROM emulates old NV-RAM setpoint storage, and the 10-bit ADC replaces external A/D chips on older boards. JTAG on-chip debug shortens bring-up of upgraded firmware, and the boot-lock Flash section enables authenticated firmware updates through an existing serial port without socketing devices on serviced boards.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA64L-8AJ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA64L-8AU | ATMEGA64L-8AI | ATMEGA64A-AUR | ATMEGA64-16AU |
|---|---|---|---|---|---|
| Package | 64-TQFP (14x14) | 64-TQFP (14x14) - same | 64-TQFP (14x14) - same | 64-TQFP (14x14) - same | 64-TQFP (14x14) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 64KB (32K x 16) | 64KB | 64KB | 64KB | 64KB |
| SRAM | 4KB | 4KB | 4KB | 4KB | 4KB |
| Maximum Clock Speed | 8MHz | 8MHz | 8MHz | 16MHz (A-generation spec) | 16MHz |
| Supply Voltage | 2.7V to 5.5V | 2.7V to 5.5V | 2.7V to 5.5V | 2.7V to 5.5V | 4.5V to 5.5V |
Key Differentiators
- Widest supply range in same footprint (vs ATMEGA64-16AU)
- 100% pin-compatible ATmega103 replacement (vs ATmega103)
- Dual UART/USART on a mid-range 8-bit AVR (vs ATMEGA32L-8AI)
Design Notes
Decouple all three VCC pins (11, 31, 52) with 100nF ceramic capacitors placed as close as possible to each pin, plus one bulk 10uF capacitor per supply rail. AVCC (pin 62) must be connected to VCC through a low-pass filter (e.g., 10uH inductor or ferrite bead plus 100nF) when ADC accuracy matters, per the ATmega64/L datasheet power-supply guidance. At 2.7V minimum operation, verify brown-out detector settings, since the BOD threshold must sit between the operating voltage floor and the minimum VCC to protect EEPROM writes.
Keep AGND (pin 63) and AREF (pin 61) routing away from the switching nodes of any upstream regulator; connect AGND to a quiet analog ground island tied to digital ground at a single point. Star-route the crystal (XTAL1/XTAL2, pins 14/13) with short traces and place load capacitors within 3-5mm of the pins to minimize jitter and startup failures. If the external memory bus (PA0-PA7, PC0-PC7, ALE, RD, WR) is used, keep the AD bus length-matched and add series 22-33 ohm resistors on ALE/WR/RD to control ringing on 5V-level strobes.
The most frequent integration error is clocking this L-grade part above 8MHz - unlike some AVR speed grades, ATMEGA64L-8AJ is not rated higher even at 5V; use ATMEGA64-16AU for faster clocks. Second, JTAG enable is fused on by default and JTAG pins PF4-PF7 double as ADC4-ADC7; if you need all eight ADC channels, disable JTAGEN via fuse or software JTD bit. Third, when migrating from ATmega103, remember register and bit positions differ - follow the Microchip migration application notes rather than reusing register definitions.
Compliance Information
Compliance attributes were not stated in the provided verified web data; verify RoHS/REACH status on the Microchip product page or distributor listing before procurement.
