ATMEGA323L-4PC - 8-bit AVR MCU 32KB Flash 4MHz DIP-40 | Microchip
MPN: ATMEGA323L-4PC ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $25.28 | $25.28 |
| 10 | $22.75 | $227.50 |
| 100 | $20.48 | $2,048.00 |
| 500 | $18.43 | $9,215.00 |
| 1,000 | $16.59 | $16,590.00 |
ATMEGA323L-4PC Overview
An 8-bit microcontroller is a single-chip computer that integrates a processor core, program memory, data memory, and peripherals on one die. Within the power-management/embedded hierarchy, the ATmega323 belongs to the AVR family - an advanced RISC architecture executing 131 powerful instructions, most in a single clock cycle, through eight general-purpose working registers and fully static operation offering up to 16 MIPS throughput at maximum frequency.
Key features of the ATMEGA323L-4PC include in-system programmable (ISP) 32KB Flash organized for self-programming, 2KB of internal SRAM for data buffering, and the AVR single-cycle RISC core that lets the L-4 speed grade sustain useful throughput even at 4MHz. The wide 2.7V to 5.5V supply range allows direct operation from a 3.3V rail while remaining 5V-tolerant, which is valuable in mixed legacy designs. The through-hole DIP-40 package makes the part ideal for prototyping, education, and socketed industrial boards.
Technically, the AVR core achieves close to 1 MIPS per MHz by fetching one instruction word from program memory on every cycle, a Harvard-architecture split that separates the 32KB Flash bus from the SRAM data path. In-system programming via the SPI serial port allows firmware updates without removing the device from the board, reducing field-service cost.
Typical applications include industrial control panels, legacy board maintenance and repair, academic embedded-lab training boards, and hobby or prototype systems that require through-hole mounting and socketed replacement.
Design consideration: the L grade is specified at 4MHz - do not clock above this rating at 2.7V to 5.5V; use the standard ATMEGA323-8 speed grade for higher frequencies.
This page synthesizes distributor pricing, drop-in alternative analysis, and sourcing information not consolidated in the manufacturer datasheet.
Drop-in alternatives for ATMEGA323L-4PC — 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 ATMEGA323L-4PC (same form factor and footprint) — differing in Package, ADC, Core Architecture, Debug Interface, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA323-8PI
✅ Drop-In✓ In Stock
$4.48 / Unit
View Datasheet →ATMEGA32-16PU
✅ Drop-In✓ In Stock
$3.68 / Unit
View Datasheet →ATMEGA32-16PI
✅ Drop-In✓ In Stock
$2.75 / Unit
View Datasheet →ATMEGA323L-4PC Maximum Ratings & Electrical Characteristics
| Core Architecture | AVR 8-bit RISC |
| Flash Program Memory | 32KB In-System Programmable |
| SRAM Data Memory | 2KB |
| Max CPU Speed (L grade) | 4 MHz |
| Max Throughput | 16 MIPS (device family max at 16 MHz) |
| Instructions | 131 instructions, most single-cycle |
| Operating Voltage Range | 2.7 V to 5.5 V |
| Package | 40-pin PDIP (DIP-40) |
| Mounting Type | Through Hole |
| Programming Method | In-System Programmable (ISP) via SPI |
ATMEGA323L-4PC 40-pin pdip (dip-40) Pin Configuration Guide
Pin configuration for ATMEGA323L-4PC (40-pin pdip (dip-40) 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 ATMEGA323L-4PC.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA323L-4PC is suitable for 6 applications: Industrial Control Panel Maintenance, Embedded Systems Education and Training Labs, Hobby and Prototype Through-Hole Projects, Legacy Firmware Preservation and Re-manufacture, Motor and Relay Sequencing Controllers, Instrumentation Front-End Data Loggers.
Industrial Control Panel Maintenance
The ATMEGA323L-4PC remains widely used to service and maintain installed industrial control panels that were designed around Atmel AVR DIP-40 MCUs. Its 2.7V to 5.5V supply range allows direct replacement into boards powered by 3.3V or 5V logic, and the 32KB ISP Flash holds the original control firmware with 2KB SRAM for runtime variables. The through-hole DIP-40 package fits original machine-pin sockets, so a failed chip can be swapped in minutes without soldering or PCB modification. The L grade's 4MHz rating matches the crystal originally fitted on these legacy boards, avoiding timing changes. Because the part is obsolete, maintenance engineers should hold buffer stock and keep an ISP programmer with the original firmware image archived.
Recommended
Embedded Systems Education and Training Labs
The ATMEGA323L-4PC is a practical teaching platform for 8-bit embedded systems courses because the DIP-40 through-hole package lets students insert and remove the chip by hand, and the ISP interface allows repeated firmware reflashing with a simple SPI programmer. The AVR core's 131 mostly single-cycle instructions make assembly-language timing behavior easy to predict, while the 32KB Flash and 2KB SRAM are sufficient for C programs with peripheral drivers. The 2.7V to 5.5V operating range supports simple bench power supplies without precision regulation. Universities favoring legacy Atmel toolchains (AVR-GCC, AVR Studio) continue to use this part in existing lab boards, where its socketed DIP format lowers per-semester replacement cost compared with soldered QFP devices.
Recommended
Hobby and Prototype Through-Hole Projects
For hobbyists and prototypers, the ATMEGA323L-4PC offers a solderable, breadboard-adaptable 40-pin DIP format that avoids the hot-air rework needed for surface-mount AVRs. The 32KB in-system programmable Flash supports bootloaders, so firmware can be updated over UART without a dedicated programmer after initial setup, and the 2KB SRAM comfortably buffers sensor data in measurement sketches. Its 2.7V to 5.5V range allows powering from three AA cells (4.5V) or a USB 5V rail. The L grade's 4MHz ceiling is acceptable for polling-based control loops and serial links used in hobby projects. Note that availability is limited to broker stock, so prototype builders may prefer the actively produced ATMEGA32-16PU with the same footprint.
Recommended
Legacy Firmware Preservation and Re-manufacture
Companies re-manufacturing out-of-production equipment need the exact MCU originally qualified in the design, and the ATMEGA323L-4PC fills that role for boards specified with the L speed grade. Its identical die to the ATMEGA323 family means firmware images, fuse settings, and timing assumptions carry over unchanged; the 32KB ISP Flash accepts the original production hex file without recompilation. The 2KB SRAM preserves real-time behavior of stack-heavy legacy code, and the 2.7V to 5.5V rating matches the original power-tree. Procurement teams should qualify broker stock with date-code verification and decap or functional testing, since obsolete AVR parts are a known counterfeit target, and simultaneously qualify the ATMEGA323-8PI as a same-die second source.
Recommended
Motor and Relay Sequencing Controllers
The ATMEGA323L-4PC suits relay and contactor sequencing controllers common in building automation retrofits, where a 4MHz clock is ample for millisecond-scale state machines and the 32KB Flash accommodates scheduling tables, communication parsing, and logging code with room to spare. The 2KB SRAM holds sequencer state and serial buffers, while in-system programming allows field firmware updates through a service header without desoldering the MCU. Operating from 2.7V to 5.5V, it tolerates supply sag from shared 5V logic rails that also power optocoupler inputs. The DIP-40 package eases repair in sealed enclosures. Designers must verify the exact timer and I/O configuration of the original board firmware, as this obsolete part is typically fitted only in existing designs.
Recommended
Instrumentation Front-End Data Loggers
In legacy instrumentation data loggers, the ATMEGA323L-4PC provides the control core that polls ADC results, formats readings, and writes to serial or memory peripherals. The 32KB ISP Flash stores logging tables and command interpreters, and 2KB SRAM buffers measurement batches before transfer. The L grade's 4MHz clock reduces core current draw in the 2.7V to 5.5V operating window, which benefits battery-backed loggers, while fully static operation preserves register contents if the clock is slowed or halted by power-management firmware. The through-hole package simplifies field replacement of the controller in long-service-life instruments. Engineers repairing such loggers should archive firmware and fuse settings, and validate that replacement broker stock executes ISP programming correctly before deployment.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA323L-4PC — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA323-8PI | ATMEGA32-16PU | ATMEGA32-16PI |
|---|---|---|---|---|
| Brand | Microchip Technology (Atmel) | Microchip Technology (Atmel) | Microchip Technology (Atmel) | Microchip Technology (Atmel) |
| Package | DIP-40 (PDIP) | DIP-40 (PDIP) - same | DIP-40 (PDIP) - same | DIP-40 (PDIP) - same |
| Flash | 32KB ISP | 32KB ISP | 32KB ISP | 32KB ISP |
| Max Clock Frequency | 4 MHz (L grade) | 8 MHz | 16 MHz | 16 MHz |
| Core | 8-bit AVR RISC (131 instructions) | 8-bit AVR RISC - identical die | 8-bit AVR RISC - newer peripheral set | 8-bit AVR RISC - newer peripheral set |
| Firmware Compatibility | Baseline (ATmega323 register map) | Identical hex file and fuses | Recompile and re-fuse required | Recompile and re-fuse required |
Key Differentiators
- True same-die drop-in exists within family (vs ATMEGA323-8PI)
- Low-voltage L grade for 3.3V rails (vs ATMEGA32-16PU)
- Baseline register map for original firmware (vs ATMEGA32-16PI)
Design Notes
Respect the L speed grade: the ATMEGA323L-4PC is limited to 4MHz regardless of supply voltage. Fitting an 8MHz or 16MHz crystal to a board carrying the L part risks out-of-spec timing across the 2.7V to 5.5V range. If a board must run faster, migrate to ATMEGA323-8PI or ATMEGA32-16PU/PI and reconfigure the AVR clock fuses accordingly - a wrong fuse setting (e.g., low-frequency crystal selected) can render the chip unresponsive and require a high-voltage parallel programmer to recover.
The 2.7V to 5.5V operating range means the same PCB can ship in either 3.3V or 5V variants, but peripheral margins change with supply: verify that external memory, RS-232 level shifters, and LCD modules meet their own minimum voltage at 2.7V. Decouple VCC with 100nF ceramic close to the DIP socket plus bulk capacitance at the regulator. Because this part is sourced from broker stock, test ISP programming and brown-out behavior on a sample from each lot before committing to production repairs.
The DIP-40 through-hole footprint is forgiving for layout, but legacy AVR designs should still keep the ISP header (MOSI/MISO/SCK/RESET/GND/VCC) routed short and place a 100nF capacitor at the socket. When substituting the ATMEGA32 family on an ATmega323 board, audit the pin function map and fuse defaults against the ATmega32 datasheet: peripheral assignments differ, and hardware built around ATmega323-specific register addresses will not function from the same hex file. Always recompile from source and re-run timing validation on substituted silicon.
Compliance Information
This is a legacy Atmel part predating modern compliance documentation; no RoHS/REACH status was found in the provided web data. Many original DIP-40 Atmel parts were non-RoHS (tin-lead finish) - verify with the specific seller's lot documentation.
