ATMEGA3250A-AUR - 8-Bit AVR MCU, 32KB Flash, 20MHz | Microchip
MPN: ATMEGA3250A-AUR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.82 | $4.82 |
| 10 | $4.48 | $44.80 |
| 100 | $4.13 | $413.00 |
| 500 | $3.86 | $1,930.00 |
| 1,000 | $3.55 | $3,550.00 |
ATMEGA3250A-AUR Overview
A microcontroller (MCU) is a single-chip computer that integrates a processor core, program memory, data memory, and peripherals on one die. Within the semiconductor hierarchy, the ATmega3250A belongs to the AVR ATmega family of 8-bit microcontrollers, which sit under the broader categories of embedded processors and integrated circuits. AVRs are widely used because their reduced instruction set (131 instructions, mostly single-cycle) delivers deterministic execution and high code density without the complexity of 32-bit cores.
Key features of the ATMEGA3250A-AUR include the advanced AVR RISC architecture with 32 general-purpose working registers, read-while-write Flash for in-system programming, JTAG boundary-scan and on-chip debugging, and 54 general-purpose I/O lines. Peripherals include SPI, USART serial interfaces, an 8-channel 10-bit ADC, and multiple power-saving sleep modes, allowing a single chip to handle sensing, control, and communication in medium-complexity systems.
Architecturally, the AVR core uses a Harvard structure with separate program and data buses, enabling one-cycle instruction fetch and execution. The A-version silicon supports 2.7 V to 5.5 V operation across the full industrial temperature range, and the picoPower-class power management provides Idle, Power-down, and Standby modes for battery-conscious designs. The 100-TQFP package exposes 54 GPIO plus power, clock, and JTAG pins, with 0.8 mm lead pitch for standard SMT assembly.
Typical applications include industrial automation controllers, building and HVAC control panels, sensor acquisition nodes, and motor-driven consumer appliances. The generous 54-I/O count and 2x USART make the 3250A especially well suited to HMI panels and multi-channel control boards where pin count, not raw throughput, is the constraint.
A key design consideration is clock selection: the 20 MHz rating applies across 4.5-5.5 V operation, while lower voltage rails require reduced maximum clock frequency, so always check the frequency-versus-voltage curve in the manufacturer datasheet before finalizing the clock source.
This page synthesizes distributor pricing, drop-in alternatives, engineering design notes, and application guidance not found in the manufacturer datasheet alone.
Drop-in alternatives for ATMEGA3250A-AUR — 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-AUR (same form factor and footprint) — differing in Package, Supply Voltage Range, Operating Temperature, Instruction Set, Instructions.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA3250PA-AUR
✅ Drop-In✓ In Stock
$2.98 / Unit
View Datasheet →ATMEGA3250-16AU
✅ Drop-In✓ In Stock
$5.74 / Unit
View Datasheet →ATMEGA6450A-AUR
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
ATMEGA3290PA-AU
✅ Drop-In✓ In Stock
$4.48 / Unit
View Datasheet →ATMEGA3290A-AU
✅ Drop-In✓ In Stock
$3.85 / Unit
View Datasheet →ATMEGA3250A-AUR Maximum Ratings & Electrical Characteristics
| Core Processor | AVR |
| Core Size | 8-Bit |
| Program Memory Size | 32 KB (16K x 16) Flash |
| EEPROM Size | 1 KB |
| RAM Size | 2 KB SRAM |
| Maximum Clock Frequency | 20 MHz |
| I/O Count | 54 general purpose I/O lines |
| Supply Voltage Range | 2.7 V to 5.5 V |
| Data Converters | 10-bit ADC, 8 channels |
| Connectivity | SPI, UART/USART |
| Debug / Scan | JTAG (IEEE 1149.1 boundary scan, on-chip debug) |
| Package | 100-TQFP (14x14 mm, 0.8 mm pitch) |
| Mounting Type | Surface Mount |
| Packaging | Tape & Reel (TR) |
| Instruction Set | 131 AVR instructions, mostly single-cycle |
| In-System Programming | Yes, ISP Flash with read-while-write |
ATMEGA3250A-AUR 100-tqfp (14x14 mm, 0.8 mm pitch) Pin Configuration Guide
Pin configuration for ATMEGA3250A-AUR (100-tqfp (14x14 mm, 0.8 mm pitch) 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-AUR.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA3250A-AUR is suitable for 6 applications: Industrial Automation Controllers, Building and HVAC Control Panels, Sensor Acquisition Nodes, Consumer Appliance Control, HMI and Operator Interface Panels, Motor Control and Actuator Drivers.
Industrial Automation Controllers
The ATMEGA3250A-AUR fits industrial control boards because 54 GPIO lines directly drive relays, contactors, indicators, and matrix keypads without expansion logic, while the 8-channel 10-bit ADC reads analog sensors such as 4-20 mA-conditioned transducers and potentiometer position feedback. SPI and USART interfaces connect isolated field-bus modules and operator displays, and JTAG supports on-board debugging during commissioning when PLC-style sequencing logic must be verified. Operating from 5 V industrial rails within the 2.7-5.5 V range gives good noise margin. Because the AVR core executes most of its 131 instructions in a single cycle at up to 20 MHz, deterministic scan loops of a few microseconds per task are achievable, adequate for machine sequencing and interlock logic where timing predictability matters more than raw throughput.
Recommended
Building and HVAC Control Panels
HVAC and building-automation panels need many discrete I/O for dampers, fans, valve actuators, and status LEDs, which is exactly the ATMEGA3250A-AUR's strength: 54 GPIO covers a full control panel with no port expanders, cutting BOM cost and PCB area. The 10-bit ADC digitizes temperature sensors (NTC thermistors), humidity inputs, and pressure transmitters, while USART links communicate with RS-485 transceivers for BMS networks. Sleep modes allow thermostat-style products to idle at low average current between samples. Designers should place RC filtering ahead of ADC channels in electrically noisy mechanical rooms and use the internal or external watchdog (via supervisor) to guarantee restart after brownouts. The 100-TQFP 14x14 mm footprint assembles on standard SMT lines with 0.8 mm pitch.
Recommended
Sensor Acquisition Nodes
For multi-channel data acquisition, the ATMEGA3250A-AUR combines an 8-channel 10-bit ADC with enough GPIO to multiplex external analog front ends and drive channel-select logic, all in one 100-TQFP device. USART and SPI interfaces stream sampled data to wireless modules or gateways, and the 2 KB SRAM buffers burst records between transmissions. The read-while-write Flash permits logging calibration constants to the 1 KB EEPROM without pausing program execution. At 20 MHz, a 10-bit conversion plus averaging completes in well under a millisecond per channel, supporting kHz-class sampling on all channels sequentially. For battery-powered loggers, prefer the ATMEGA3250PA picoPower version, which reduces power-down current dramatically while keeping the identical footprint, allowing one PCB design across both power profiles.
Recommended
Consumer Appliance Control
Washing machines, dishwashers, and small cooking appliances require simultaneous motor-drive sequencing, user-interface handling, and safety interlock monitoring - a workload the ATMEGA3250A-AUR handles with its 54 GPIO and single-cycle 8-bit core. GPIO drives triac optocouplers, buzzer, and a 7-segment or LED matrix display; the ADC reads motor current shunts and NTC temperature probes for closed-loop protection. The 5.5 V upper supply range suits transformer-derived 5 V rails common in white goods, and the industrial temperature grade tolerates warm cabinets. JTAG allows manufacturing test integration on the production line. Firmware updates in the field are possible through ISP because the Flash supports read-while-write programming, letting service technicians reflash the control board without removing it from the appliance.
Recommended
HMI and Operator Interface Panels
Operator interface panels demand high pin count for keypad matrices (e.g., 8x8 = 16 pins), multiple LED banks, buzzer, and backlight control - the ATMEGA3250A-AUR's 54 GPIO absorbs this with headroom for a serial link to a main controller. Its 32 KB Flash stores multi-language string tables and menu trees that smaller AVRs cannot hold, and 2 KB SRAM supports line-buffered display updates. USART connects to RS-232/RS-485 or USB-serial bridges, while SPI drives segment/TFT-assist controllers. Scan latency of the full keypad matrix at 20 MHz is far below human-perception thresholds, giving responsive debounced input. Because port pins tolerate 5 V logic, interfacing to legacy industrial signaling needs no level shifting, simplifying mixed-voltage panel designs.
Recommended
Motor Control and Actuator Drivers
The ATMEGA3250A-AUR supervises small motor systems by generating PWM on GPIO timers, reading back current via the 10-bit ADC, and sequencing contactors and limit switches on its 54 I/O lines. Typical loads include DC fans, pumps, blinds, and gate actuators, where the AVR's deterministic single-cycle core makes control-loop jitter predictable. USART interfaces to a higher-level controller or gateway, while EEPROM retains runtime hour counters and fault logs across power cycles. Designers should size gate-drive circuitry external to the MCU, since the GPIO drive is intended for logic, not power; the ADC input must be protected from inductive kick with clamping networks. The 5 V operation and wide 2.7 V floor keep the controller alive through brownout events common on shared motor supplies.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA3250A-AUR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA3250PA-AUR | ATMEGA3250-16AU | ATMEGA6450A-AUR | ATMEGA3290PA-AU |
|---|---|---|---|---|---|
| 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 | 2 KB | 2 KB | 2 KB | 4 KB | 2 KB |
| Max Clock Frequency | 20 MHz | 20 MHz | 16 MHz | 20 MHz | 20 MHz |
| General Purpose I/O | 54 | 54 | 54 | 54 | Fewer (pins shared with LCD controller) |
| Power Class | Standard | picoPower (lower sleep current) | Standard | Standard | picoPower |
| Special Peripherals | ADC, SPI, USART, JTAG | ADC, SPI, USART, JTAG | ADC, SPI, USART, JTAG | ADC, SPI, USART, JTAG | ADC, SPI, USART, JTAG + LCD controller |
Key Differentiators
- 20 MHz maximum clock speed (vs ATMEGA3250-16AU)
- Standard power class at full feature parity (vs ATMEGA3250PA-AUR)
- Right-sized 32 KB Flash with room to grow (vs ATMEGA6450A-AUR)
- All 54 pins available as general-purpose I/O (vs ATMEGA3290PA-AU)
Design Notes
Decouple every VCC and AVCC pin pair with 100 nF ceramic capacitors placed within 5 mm of the pins, plus one bulk 10 uF capacitor per supply rail. The 100-TQFP has multiple VCC/GND pairs; omitting any local decoupling shows up as ADC noise and sporadic brownout resets when relays switch on the same board. Keep AVCC filtered through an LC network (ferrite bead plus 1 uF) if the ADC is used, since motor or relay noise on the digital rail degrades the 10-bit converter's effective resolution.
The 20 MHz maximum rating applies only at the upper end of the supply range; consult the frequency-versus-voltage curve in the Microchip datasheet before choosing a crystal. At reduced VDD the safe maximum clock drops, and overclocking beyond the derated limit causes marginal timing failures that appear only at temperature extremes. For the 16 MHz ATMEGA3250-16AU variant, never exceed 16 MHz regardless of supply. Always fit the manufacturer-recommended crystal load capacitors and add a series resistor (typically 100-330 ohm) on XTAL2 to limit drive level.
On the 100-TQFP (0.8 mm pitch), route the JTAG traces (TCK, TMS, TDI, TDO) to a 2x5 header even if debugging is not planned - retrofitting access later requires cutting traces. Keep the RESET trace short and add a 10 kOhm pull-up plus 100 nF to ground for robust power-up. Unused GPIO should be defined as outputs driving low or inputs with pull-ups in firmware; floating inputs increase supply current unpredictably. Leave thermal reliefs on the GND pads for inspectable rework during prototyping.
A frequent substitution error is swapping ATMEGA3250A and ATMEGA3290A boards: the 3290 family dedicates many port pins to its integrated LCD controller, so firmware written for the 3250A will not drive the same pins. Verify the exact ordering-code suffix (AUR = RoHS 100-TQFP, tape and reel) when purchasing, since ATMEGA3250A-AU (tray) and -AN (lead-frame variants) are not footprint-identical. Finally, enable the brown-out detector in fuses for designs switching inductive loads, otherwise resets can corrupt EEPROM data.
Compliance Information
The AUR suffix denotes Microchip's RoHS-compliant, lead-free matte-tin package on tape and reel. REACH and halogen-free status should be confirmed on Microchip's environmental compliance page for the specific date code.
