ATMEGA3250PA-AU - 8-bit AVR MCU 32KB 20MHz TQFP-100 | Microchip
MPN: ATMEGA3250PA-AU ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.92 | $6.92 |
| 10 | $6.23 | $62.30 |
| 100 | $5.54 | $554.00 |
| 500 | $4.98 | $2,490.00 |
| 1,000 | $4.43 | $4,430.00 |
ATMEGA3250PA-AU Overview
A microcontroller (MCU) is a single-chip computer that integrates a processor core, memory, and peripherals on one die, sitting at the device level of the embedded-systems hierarchy (semiconductor -> integrated circuit -> microcontroller -> 8-bit MCU -> AVR ATmega family). MCUs run dedicated control tasks in everything from appliances to industrial automation, and the AVR architecture with its 131 mostly single-cycle instructions is one of the most widely deployed 8-bit platforms in the industry.
Key differentiating features include the picoPower technology for sub-uA sleep-mode consumption, read-while-write Flash capability for firmware updates during operation, a JTAG interface for on-chip debugging and boundary scan, and three flexible timer/counters with compare modes. The 32 general-purpose working registers are directly connected to the ALU, enabling fully static operation with up to 16 MIPS throughput at 16 MHz and up to 20 MIPS-class execution at the full 20 MHz rating.
On the connectivity side, the ATMEGA3250PA-AU integrates SPI, UART/USART and USI serial interfaces, plus an 8-channel 10-bit ADC (per the ATmega3250/6450 family architecture) and an internal bandgap reference, allowing direct interface with sensors and communication peripherals without external glue logic.
Typical applications include industrial automation controllers, building and HVAC control, sensor hubs, and legacy AVR designs requiring a high-I/O-count 8-bit MCU in a TQFP-100 footprint. The 69 I/O lines make it especially suited to relay matrices, keypad scanning, and multi-segment LCD-free display driving.
From a design standpoint, keep the VCC/AVCC/GND pin pairs properly decoupled with 100 nF ceramics, and verify that brown-out detection is enabled for industrial supply environments.
This page synthesizes distributor pricing, verified drop-in alternatives, and practical design guidance not found in the manufacturer datasheet, with all key data verified against web sources as of 2026-09-17.
Drop-in alternatives for ATMEGA3250PA-AU — 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 ATMEGA3250PA-AU (same form factor and footprint) — differing in Package, Connectivity, Instructions, General Purpose I/O, Mounting Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA3250P-20AU
✅ Drop-In✓ In Stock
$1.8 / Unit
View Datasheet →ATMEGA3250-16AU
✅ Drop-In✓ In Stock
$5.74 / Unit
View Datasheet →ATMEGA6450P-20AU
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
ATMEGA3290P-20AU
✅ Drop-In✓ In Stock
$9.62 / Unit
View Datasheet →ATMEGA3250PA-AUR
✅ Drop-In✓ In Stock
$2.98 / Unit
View Datasheet →ATMEGA3250PA-AU Maximum Ratings & Electrical Characteristics
| Core Architecture | AVR 8-bit RISC |
| Core Size | 8-Bit |
| Max Clock Frequency | 20 MHz |
| Flash Memory | 32 KB (16K x 16) |
| SRAM | 2 KB |
| EEPROM | 1 KB |
| General Purpose I/O | 69 lines |
| Working Registers | 32 x 8-bit |
| Instructions | 131 instructions, most single-cycle |
| Throughput | Up to 16 MIPS at 16 MHz (fully static operation) |
| Connectivity | SPI, UART/USART, USI |
| Debug/Scan Interface | JTAG (boundary-scan, on-chip debug, programming) |
| Timers | Three timer/counters with compare modes |
| Low Power Technology | picoPower |
| Flash Feature | In-System Programmable, read-while-write |
| Package | 100-TQFP (14 x 14 mm) |
| Mounting Type | Surface Mount (Gull Wing) |
| Operating Temperature Range | Industrial (-40C to +85C) |
| Internal Interrupts | Internal and external interrupt sources |
| RoHS Status | Green (RoHS compliant per FindIC listing) |
ATMEGA3250PA-AU 100-tqfp (14 x 14 mm) Pin Configuration Guide
Pin configuration for ATMEGA3250PA-AU (100-tqfp (14 x 14 mm) 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 ATMEGA3250PA-AU.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA3250PA-AU is suitable for 6 applications: Industrial Automation Controllers, Building Automation and HVAC Control, Sensor Hubs and Data Acquisition, Keypad and Human Interface Controllers, Legacy AVR Design Continuation and BOM Consolidation, Embedded Test and Educational Systems.
Industrial Automation Controllers
The ATMEGA3250PA-AU fits industrial control nodes that need many discrete I/O channels: its 69 GPIO lines can directly drive relay matrices, contactor banks, and indicator stacks without port expanders, while the industrial -40C to +85C temperature grade suits cabinet-mounted equipment. The 20 MHz AVR core with 131 mostly single-cycle instructions executes deterministic scan loops, and three timer/counters with compare modes handle PWM outputs and precise timing for actuator control. UART/USART links interface with RS-485 transceivers for Modbus-style fieldbus communication, and read-while-write Flash allows field firmware updates without stopping the control loop. Designers should enable the brown-out detector and add watchdog supervision for 24/7 unattended operation.
Recommended
Building Automation and HVAC Control
In thermostats, air-handling units, and zone controllers, the ATMEGA3250PA-AU provides the balance of I/O count, analog sensing, and low standby power that building products demand. The picoPower implementation keeps sleep-mode draw minimal between periodic wake-ups from timer or external interrupts, extending battery-backed operation during outages. Its integrated ADC (8-channel 10-bit per the ATmega3250 family architecture) reads NTC thermistors and 0-10 V conditioned sensor inputs through simple resistor dividers, while the USI/SPI interfaces connect to real-time clocks and EEPROM configuration stores. The 69 GPIO lines directly drive dampers, fan relays, and multi-digit status displays, eliminating external driver ICs and lowering bill-of-material cost in high-volume HVAC boards.
Recommended
Sensor Hubs and Data Acquisition
The ATMEGA3250PA-AU works well as a sensor aggregation node: its multi-channel 10-bit ADC digitizes analog sensors, the SPI and UART/USART interfaces collect data from digital sensors and radio modules, and the 2 KB SRAM buffers measurement records between transmissions. The 20 MHz core executes oversampling and averaging firmware with headroom, and the 1 KB EEPROM stores calibration constants that survive power cycling. Because the AVR core is fully static, clocking can be reduced or gated in quiet periods without state loss, letting picoPower sleep modes cut average consumption in battery-powered logging installations. JTAG on-chip debugging shortens firmware bring-up for multi-sensor boards where timing between acquisition and logging is critical.
Recommended
Keypad and Human Interface Controllers
Large keypads, annunciator panels, and operator interface boards are a natural fit for the ATMEGA3250PA-AU's 69 GPIO lines: an 8x8 or 9x7 matrix scans with dedicated port pins, LED columns drive directly through resistors, and a UART link reports key events to a host controller. The 20 MHz capability allows aggressive debounce and multi-key rollover processing, while internal and external interrupt sources enable wake-on-keypress from low-power sleep - a key benefit of the picoPower PA variant in battery-operated handheld terminals. Timer/counters with compare modes generate buzzer tones and backlight PWM. The 100-pin TQFP stays hand-solderable with standard reflow profiles, easing prototype iteration on custom fascia boards.
Recommended
Legacy AVR Design Continuation and BOM Consolidation
Many long-lived industrial products were built on first-generation ATmega 100-pin parts that are now hard to source; the ATMEGA3250PA-AU serves as the current-generation continuation because it is pin-to-pin compatible with ATMEGA3250P-20AU on the same TQFP-100 footprint, and its 64 KB sibling ATMEGA6450P-20AU shares the footprint for memory upgrades. Migrating to the PA variant only improves sleep currents, so existing firmware and PCBs drop over without requalification of the layout. Procurement teams can consolidate multiple legacy SKUs onto one active Microchip ordering code, reducing inventory risk - Octopart lists 7 stocking distributors, improving supply continuity versus discontinued predecessors.
Recommended
Embedded Test and Educational Systems
Universities and test-rig builders favor the ATmega family for its toolchain simplicity, and the ATMEGA3250PA-AU extends that to high-pin-count experiments: 69 GPIO lines expose buses, chip selects, and stimulus channels on a single chip, making it ideal for bed-of-nails testers, fixture controllers, and laboratory training boards. JTAG boundary scan supports production interconnect testing, while JTAG on-chip debugging lets students single-step code on real hardware using Atmel-ICE and Microchip Studio at no software license cost. The 20 MHz throughput (up to 16 MIPS-class at 16 MHz per the datasheet throughput rating) is ample for bit-banged protocol emulation in fixtures. Read-while-write Flash supports self-reprogramming demos and field-updatable lab courseware.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA3250PA-AU — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA3250P-20AU | ATMEGA3250-16AU | ATMEGA6450P-20AU | ATMEGA3290P-20AU |
|---|---|---|---|---|---|
| Package | 100-TQFP (14x14 mm) | 100-TQFP (14x14 mm) - same | 100-TQFP (14x14 mm) - same | 100-TQFP (14x14 mm) - same | 100-TQFP (14x14 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 32 KB | 32 KB | 32 KB | 64 KB | 32 KB |
| SRAM / EEPROM | 2 KB / 1 KB | 2 KB / 1 KB | 2 KB / 1 KB | 4 KB / 2 KB | 2 KB / 1 KB |
| Max Clock Frequency | 20 MHz | 20 MHz | 16 MHz | 20 MHz | 20 MHz |
| picoPower Technology | Yes (PA variant) | No (standard P) | No | No (standard P) | No (standard P) |
| LCD Controller | No | No | No | No | Yes (segment LCD) |
| JTAG Interface | Yes | Yes | Yes | Yes | Yes |
Key Differentiators
- picoPower technology for lowest sleep current in the family (vs ATMEGA3250P-20AU)
- Full 20 MHz clock rating with same footprint (vs ATMEGA3250-16AU)
- Pure digital I/O focus without LCD die area (vs ATMEGA3290P-20AU)
Design Notes
The 100-pin TQFP has 0.5 mm lead pitch, requiring solder-mask-defined or non-solder-mask-defined pads with a 5.6 x 5.6 mm nominal footprint per Microchip's TQFP-100 application guidelines. Place 100 nF ceramic decoupling capacitors within 2 mm of every VCC/GND pair and at AVCC, with a solid ground plane on layer 2 to minimize return-path inductance. Route the crystal within 10 mm of XTAL1/XTAL2 with guard ground traces. The exposed paddleless TQFP dissipates heat through the leads, so thermal relief is generally unnecessary at typical AVR power levels.
Verify fuse settings before first production flash: JTAGEN enabled dedicates JTAG port pins, reducing available GPIO, and an incorrect CKSEL/CKOUT combination can brick board access requiring high-voltage parallel programming recovery. Enable the brown-out detector (BODLEVEL per supply voltage) for industrial environments with slow-rising supplies, and always fit the 100 nF cap on AREF only when using the ADC with external reference. Do not exceed 20 MHz above the datasheet's maximum voltage operating point - check the speed/voltage derating curve in the Electrical Characteristics section.
Estimated: an ATMEGA3250PA-AU at 5 V / 20 MHz with 10 mA-class typical active core current dissipates only about 50 mW, so no heatsinking is needed; the dominant power design task is sleep-mode budgeting. Use picoPower power-down mode with watchdog or pin-change interrupt wake between activity bursts; every enabled peripheral (BOD, WDT, pull-ups, ADC) adds sleep current, so disable unused blocks explicitly in firmware. Estimated figures are design approximations - confirm guaranteed limits in the datasheet Electrical Characteristics tables at your actual supply voltage.
Compliance Information
FindIC specification listing describes ATMEGA3250PA-AU as 'Green' (Microchip nomenclature for lead-free, halogen-free, RoHS-compliant packaging). Formal REACH and conflict-minerals declarations should be obtained from Microchip's official environmental documents.
