ATMEGA3250A-AN - 32KB AVR MCU, 20MHz, 69 I/O | Microchip
MPN: ATMEGA3250A-AN ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.2 | $5.20 |
| 10 | $4.68 | $46.80 |
| 100 | $4.16 | $416.00 |
| 500 | $3.64 | $1,820.00 |
| 1,000 | $3.12 | $3,120.00 |
ATMEGA3250A-AN Overview
An 8-bit AVR microcontroller is a Harvard-architecture processor that executes most of its 130 powerful instructions in a single clock cycle. Within the power-management hierarchy, it functions as an embedded control IC that combines CPU, program memory, data memory, and peripherals such as SPI and UART/USART on a single chip, making it a complete embedded system solution for cost-sensitive designs.
Key features include the Advanced RISC architecture with most single-cycle instruction execution, in-system programmable (ISP) flash allowing firmware updates on the assembled PCB, an internal RC oscillator reducing external component count, and 69 I/O lines that enable direct drive of large keypads, LED segments, and multi-peripheral systems without port expanders.
Technically, the device belongs to the ATmega3250/6450 family of high-performance, low-power AVR controllers. Program memory is organized as 16K x 16 flash, data SRAM as 2K x 8, and a separate 1KB EEPROM provides non-volatile storage for calibration data that survives firmware reprogramming. Connectivity peripherals include SPI and UART/USART interfaces for communication with displays, memory, and industrial networks.
Typical applications include large-appliance control panels, building automation nodes, industrial HMI boards with many keys and LEDs, and battery-powered metering products where the low-power AVR core and internal oscillator minimize system cost.
When designing, verify the supply-voltage operating envelope against the 20MHz speed grade and provide decoupling on all VCC/AVCC pins of the 100-lead TQFP, since high pin count increases transient current demand.
This page synthesizes verified distributor data, same-family drop-in alternatives, and practical design guidance not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA3250A-AN — 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 ATMEGA3250A-AN (same form factor and footprint) — differing in Connectivity, I/O Ports, Instructions, Number of I/O, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA3250A-AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.5 / Unit
View Datasheet →ATMEGA3250-16AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$5.74 / Unit
View Datasheet →ATMEGA6450A-AN
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
ATMEGA3250P-AN
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
ATMEGA3250A-AN Maximum Ratings & Electrical Characteristics
| Core Processor | AVR |
| Core Size | 8-Bit |
| Program Memory Size | 32KB (16K x 16) |
| Program Memory Type | FLASH (In-System Programmable) |
| RAM Size | 2K x 8 |
| EEPROM Size | 1KB |
| Speed | 20MHz |
| Number of I/O | 69 |
| Oscillator Type | Internal |
| Connectivity | SPI, UART/USART |
| Architecture | Advanced RISC, 130 instructions |
| Operating Temperature | -40C to +105C |
| Package / Case | TQFP-100 |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant (Green, per FindIC listing) |
ATMEGA3250A-AN tqfp-100 Pin Configuration Guide
Pin configuration for ATMEGA3250A-AN (tqfp-100 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 ATMEGA3250A-AN.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA3250A-AN is suitable for 6 applications: Large Appliance Control Panels, Industrial HMI and Keypad Boards, Building Automation Nodes, Metering and Data Loggers, LED Display and Signage Controllers, Legacy AVR Design Continuity.
Large Appliance Control Panels
The ATMEGA3250A-AN's 69 general-purpose I/O lines let a single 100-lead TQFP directly drive multi-key keypads, LED segment banks, relay outputs, and buzzer circuits in washing machines, cookers, and dishwashers without external I/O expanders. The 32KB flash comfortably holds state machines, menus, and fault-logging code, while the 1KB EEPROM stores user settings and cycle counters through power cycles. Its internal oscillator removes the crystal BOM item, and operation to +105C covers installation near heat-generating loads. Placing the MCU on a two-layer PCB with 100nF decoupling per VCC pin yields a very low-cost, high-I/O control node typical of mainstream white-goods platforms.
Recommended
Industrial HMI and Keypad Boards
Industrial human-machine-interface boards benefit from the ATMEGA3250A-AN's combination of 69 I/O and a 20MHz AVR core: scanned key matrices of up to 8x8, banked LED indicators, and UART links to a main controller all attach directly. SPI drives graphical LCD or segment LCD controllers, while the UART/USART handles Modbus-style serial communication at standard rates. The -40C to +105C operating range suits panel installations in unconditioned factory environments. Because 32KB flash supports in-system programming, firmware with new menu languages or protocol variants can be flashed on the assembled board through the ISP header, extending field-service life without desoldering the device.
Recommended
Building Automation Nodes
In building automation, the ATMEGA3250A-AN serves as a zone controller reading occupancy switches, temperature-sensor buses, and damper feedback while driving relays and status LEDs across its 69 I/O lines. The SPI peripheral interfaces external ADCs or EEPROM when additional analog channels are needed, and the USART connects to RS-485 transceivers for multi-drop networked control. Its low-power AVR architecture and internal oscillator simplify battery-backed nodes, and the separate 1KB EEPROM retains setpoints and schedules across power outages without external non-volatile memory. The 100-lead TQFP's high integration replaces discrete glue logic, reducing board area and assembly cost in distributed I/O modules.
Recommended
Metering and Data Loggers
Energy, water, and heat meters use the ATMEGA3250A-AN for its balanced resource set: 32KB flash holds metrology and communication firmware, 2KB SRAM buffers measurement samples, and the 1KB EEPROM archives cumulative registers that must survive power loss. The USART streams readings to remote displays or gateways, while unused I/O drives pulse outputs and tamper switches - the 69-line count covers multi-phase meter front ends. The internal oscillator plus low-power sleep modes suits always-on logging duty, and the +105C rating tolerates enclosure temperatures in outdoor or panel-mounted meters. In-system programming allows calibration-table and tariff-schedule updates during production and field service.
Recommended
LED Display and Signage Controllers
Multiplexed LED displays, numeric signage, and indicator clusters are a natural fit for the ATMEGA3250A-AN: dozens of the 69 I/O lines drive rows and columns directly or through transistor arrays, while the 20MHz core executes fast multiplexing ISRs that keep refresh rates flicker-free. The 32KB flash stores glyph tables, animation sequences, and serial command parsers, and the USART accepts content updates from a host controller or RS-485 line. Because the AVR executes most instructions in a single cycle, deterministic refresh timing is easy to achieve without DMA. The internal oscillator further simplifies sign PCBs where a crystal would add cost and failure points.
Recommended
Legacy AVR Design Continuity
Many long-lifecycle products - agricultural controllers, HVAC units, and industrial sensors - were built around the Atmel megaAVR family and still require the same instruction set, peripheral map, and ISP programming flow. The ATMEGA3250A-AN keeps those designs alive with an active-production 20MHz, +105C part in the familiar TQFP-100 footprint. Boards laid out for ATMEGA3250-16AU can adopt the -AN without PCB changes, gaining speed headroom for added features. Since the AVR toolchain (AVR-GCC, AVR ISP, JTAG ICE-class debuggers) still supports the family, firmware maintenance costs remain low, making this part an economical bridge for service parts and continued production.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA3250A-AN — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA3250A-AU | ATMEGA3250-16AU | ATMEGA6450A-AN | ATMEGA3250P-AN |
|---|---|---|---|---|---|
| Package | TQFP-100 | TQFP-100 - same | TQFP-100 - same | TQFP-100 - same | TQFP-100 - same |
| Brand | Microchip Technology (Atmel) | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 32KB | 32KB | 32KB | 64KB | 32KB |
| SRAM | 2KB | 2KB | 2KB | 4KB | 2KB |
| Max Clock Speed | 20MHz | 20MHz | 16MHz | 20MHz | 20MHz |
| I/O Count | 69 | 69 | 69 | 69 | 69 |
| Operating Temperature | -40C to +105C | -40C to +85C | -40C to +85C | -40C to +105C | -40C to +105C |
| Power Feature | Standard low-power AVR | Standard low-power AVR | Standard low-power AVR | Standard low-power AVR | picoPower sleep modes |
Key Differentiators
- Extended +105C operating range (vs ATMEGA3250A-AU)
- 20MHz clock speed (vs ATMEGA3250-16AU)
- Lowest-cost 32KB option (vs ATMEGA6450A-AN)
Design Notes
Provide one 100nF ceramic decoupling capacitor per VCC/AVCC pin pair as close as possible to the 100-lead TQFP, plus a 4.7uF to 10uF bulk capacitor near the supply entry. The high I/O count means many outputs switching simultaneously can induce supply droop and ground bounce; a solid ground plane and short return paths are essential for clean ADC and oscillator behavior.
Keep the ISP programming header (MOSI, MISO, SCK, RESET, VCC, GND) on every production board so firmware can be updated after assembly. If using the internal RC oscillator, no crystal routing is needed, but if an external clock is used at 20MHz, route XTAL traces short and guard them with ground to prevent spurious clocking near switching I/O.
Do not confuse speed and temperature suffixes when purchasing: the -AN suffix denotes the 20MHz +105C grade, while -AU parts are typically -40C to +85C. Substituting a lower grade in an enclosure rated above 85C risks parametric drift and field failures. Always verify RESET fuse settings (external vs internal clock) before flashing code ported from other megaAVR variants.
Compliance Information
FindIC listing describes the part as Green, RoHS-compliant TQFP with 105C rating. AEC-Q100 status not stated in provided data.
