ATMEGA3250-16AU - 8-bit AVR MCU 16MHz 32KB Flash | Microchip
MPN: ATMEGA3250-16AU β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.11 | $8.11 |
| 10 | $7.57 | $75.70 |
| 100 | $6.85 | $685.00 |
| 500 | $6.21 | $3,105.00 |
| 1,000 | $5.74 | $5,740.00 |
ATMEGA3250-16AU Overview
A microcontroller is a single-chip computer that integrates a processor core, program memory, data memory, and peripheral functions such as timers, serial interfaces, and analog-to-digital converters. Within the semiconductor hierarchy, the ATmega3250 belongs to the AVR ATmega family of 8-bit microcontrollers, a subset of embedded MCUs used in industrial control, appliances, and instrumentation where moderate processing power and rich I/O are required without the cost of a 32-bit platform.
Key features include the advanced AVR RISC architecture with 131 powerful instructions, most of which execute in a single clock cycle, delivering up to 16 MIPS throughput at 16 MHz. The 32 KB Flash supports In-System Programming with read-while-write capability, enabling firmware updates in the field. A JTAG interface provides on-chip debugging and boundary-scan testing, a critical asset on dense 100-pin boards.
Technically, the device combines three flexible timer/counters with compare modes, internal and external interrupt sources, a programmable serial USART, SPI and TWI (I2C) interfaces, an 10-channel 10-bit ADC, and a programmable Watchdog Timer with internal oscillator. Five power-saving modes, including idle and power-down, support low average-power designs, and the core is manufactured in Microchip's high-density non-volatile memory process.
Typical applications include industrial automation controllers, HVAC and building control boards, point-of-sale and metering equipment, and consumer appliances that need many I/O lines. The 69 GPIO count and JTAG make it well suited for relay- and keypad-heavy boards.
When designing, note that the -16AU speed grade requires a 4.5 V to 5.5 V supply for 16 MHz operation; at lower voltages the maximum safe clock frequency drops, so verify the voltage-frequency curve in the datasheet before overclocking.
This page synthesizes distributor pricing, drop-in family alternatives, design notes, and SEO-structured comparison data not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA3250-16AU β 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 ATMEGA3250-16AU (same form factor and footprint) β differing in Package, Instructions, Connectivity, Speed, RoHS Status.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA3250A-16AU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA6450-16AU
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$7.85 / Unit
View Datasheet βATMEGA6490-16AU
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$8.65 / Unit
View Datasheet βATMEGA3290-16AU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA3290P-20AU
β Drop-Inβ In Stock
$9.62 / Unit
View Datasheet βATMEGA3250-16AU Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Core Size | 8-bit |
| Maximum Clock Frequency | 16 MHz |
| Flash Memory | 32 KB (16K x 16) |
| EEPROM | 1 KB |
| SRAM | 2 KB |
| Supply Voltage Range | 4.5 V to 5.5 V |
| General Purpose I/O | 54/69 I/O lines |
| I/O Ports | 32 |
| Instructions | 131 powerful instructions |
| Interfaces | USART, SPI, TWI (I2C), JTAG |
| Timers | Three flexible timer/counters with compare modes |
| Debug / Test | JTAG boundary-scan and on-chip debugging |
| Programming | In-System Programmable (ISP) Flash with read-while-write |
| Operating Temperature | -40C to +85C (industrial) |
| Package | 100-TQFP (14x14 mm), 0.80 mm pitch |
| Mounting Type | Surface Mount |
| Lifecycle Status | ACTIVE |
ATMEGA3250-16AU 100-tqfp (14x14 mm), 0.80 mm pitch Pin Configuration Guide
Pin configuration for ATMEGA3250-16AU (100-tqfp (14x14 mm), 0.80 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 ATMEGA3250-16AU.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA3250-16AU is suitable for 6 applications: Industrial Automation Controllers, HVAC and Building Control, Metering and POS Equipment, Consumer Appliance Control, Test and Measurement Instrumentation, Lighting and Motor Control Panels.
Industrial Automation Controllers
The ATMEGA3250-16AU fits industrial automation and machine-control boards that require many relay, sensor, and keypad connections: its 54/69 general purpose I/O lines and 32 I/O ports cover dense digital I/O expansion without external port expanders. The 16 MHz AVR core with 131 mostly single-cycle instructions provides deterministic interrupt response for sequencer and interlock logic, while the 32 KB ISP Flash with read-while-write supports field firmware updates during machine servicing. JTAG boundary scan verifies solder quality on the 100-pin TQFP, reducing production escapes on two-sided boards. Typical designs pair the MCU with an RS-485 transceiver over its USART for Modbus-style networking and use the 1 KB EEPROM to store calibration and recipe data through power cycles. The 4.5 V to 5.5 V supply matches legacy 5 V industrial logic levels directly, eliminating level-shifting.
Recommended
HVAC and Building Control
In HVAC controllers, boiler management, and room-control panels, the ATMEGA3250-16AU offers the right mix of analog inputs, serial links, and low-cost integration. Multiple sensor channels connect to its ADC inputs (per the mega family datasheet feature set), while three flexible timer/counters with compare modes generate PWM outputs for damper motors and variable-speed fans. The 5 V operation tolerates electrically noisy HVAC cabinets better than 3.3 V parts, and the Watchdog Timer with its own internal oscillator provides autonomous recovery from software hangs - a standard requirement in building safety logic. The 2 KB SRAM handles PID state plus a small communication stack, and the 1 KB EEPROM retains setpoints and runtime hours across power outages. JTAG on-chip debugging shortens commissioning cycles where panel access is difficult.
Recommended
Metering and POS Equipment
Electricity, water, and payment-terminal boards benefit from the ATMEGA3250-16AU's balance of security, memory, and I/O. The 32 KB Flash accommodates metering firmware plus a communication stack over USART or SPI, and the 1 KB EEPROM stores tariff tables and cumulative counters with byte-level endurance suitable for frequent writes. Its JTAG boundary-scan capability is valuable for ICT testing of dense 100-TQFP assemblies in volume production, catching open solder joints that bed-of-nails fixtures can miss on fine-pitch parts. Five power-saving modes, including power-down, allow battery-backed meter boards to wake on interrupt, log a reading, and return to sleep, extending backup-battery life during outages. The 69 I/O lines drive keypads, displays, and pulse-counting inputs on a single MCU, reducing BOM count versus smaller parts plus port expanders.
Recommended
Consumer Appliance Control
Washers, dishwashers, ovens, and similar white goods need exactly what the ATMEGA3250-16AU supplies: dozens of I/O lines for buttons, heaters, valves, and motors, timers with PWM for motor speed control, and a robust 5 V platform. The three flexible timer/counters with compare modes drive triac-firing or motor PWM channels directly, and the internal oscillator option lets cost-optimized boards run without an external crystal when timing precision allows. The 16 MIPS throughput at 16 MHz comfortably runs menu logic, sensor filtering, and a display driver simultaneously. Because the Flash is In-System Programmable, manufacturers can update firmware through a service connector without unsoldering the MCU - important for products that see long service lives and mid-cycle feature updates. Industrial temperature rating supports uncooled appliance control boxes.
Recommended
Test and Measurement Instrumentation
Bench instruments, panel meters, and data loggers use the ATMEGA3250-16AU where deterministic 8-bit control and rich peripherals matter more than DSP horsepower. The 10-bit ADC channels sample sensor and rail-monitor inputs, the USART and SPI/TWI interfaces stream results to displays, PCs, or external converters, and the 2 KB SRAM buffers measurement records between communication bursts. At 16 MHz the single-cycle core delivers precise bit-banged timing protocols that jitter-sensitive instruments sometimes require, while hardware timers offload gating and pulse counting. JTAG on-chip debugging is a particular advantage here: engineers can set breakpoints inside ISR-heavy measurement code and inspect the 32 working registers in real time. The 100-pin TQFP provides enough I/O for front-panel keypads, multi-range relays, and backlights on a single controller, simplifying layout and EMI management.
Recommended
Lighting and Motor Control Panels
Dimmer racks, stage-lighting consoles, and small motor-control panels exploit the ATMEGA3250-16AU's timer PWM channels and dense I/O. Compare-mode timer outputs generate phase-control or PWM drive signals for MOSFET half-bridges and triac stages, while other GPIO banks handle enable lines, fault-feedback inputs, and operator interfaces. The 5 V supply drives logic-level MOSFET gates directly in many designs, and the 16 MHz core executes closed-loop current or speed-control loops at kilohertz rates with headroom. The Watchdog Timer with independent internal oscillator enforces fail-safe shutdown of power stages if firmware locks - a key safety property in motor panels. Using the same 100-TQFP footprint across product variants (3250 for 32 KB builds, 6450 for feature-rich 64 KB builds) lets manufacturers share one PCB layout across a product family.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA3250-16AU β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA3250A-16AU | ATMEGA6450-16AU | ATMEGA3290-16AU | 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 | 64 KB | 32 KB | 32 KB |
| SRAM | 2 KB | 2 KB | 4 KB | 2 KB | 2 KB |
| Maximum Clock Frequency | 16 MHz | 16 MHz | 16 MHz | 16 MHz | 20 MHz |
| Supply Voltage | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 1.8 V to 5.5 V (PicoPower) |
| LCD Controller | No | No | Yes | Yes | Yes |
| General Purpose I/O | 54/69 I/O lines | 54/69 I/O lines | 54/69 I/O lines (some LCD-shared) | 54 I/O lines (LCD-shared) | 54 I/O lines (LCD-shared) |
| Power-Saving Features | 5 sleep modes incl. power-down | 5 sleep modes incl. power-down | 5 sleep modes incl. power-down | 5 sleep modes incl. power-down | PicoPower low-power technology |
Key Differentiators
- Lowest-risk production continuity (vs ATMEGA3250A-16AU)
- More general-purpose I/O than LCD-family siblings (vs ATMEGA3290-16AU)
- Cost/memory trade-off versus big-memory family (vs ATMEGA6450-16AU)
- Simpler power design than PicoPower variants (vs ATMEGA3290P-20AU)
Design Notes
The -16AU speed grade requires a 4.5 V to 5.5 V supply for reliable 16 MHz operation; below this range the maximum guaranteed clock frequency falls per the datasheet voltage-frequency curve. Decouple every VCC/AVCC pin pair with 100 nF ceramics placed within 5 mm of the pins, plus one bulk 10 uF per board. Keep the analog supply pin fed through an RC or ferrite filter if the ADC is used, since switching noise from relay coils on the same 5 V rail directly degrades ADC accuracy.
On the 100-pin TQFP (0.8 mm pitch), use a land pattern per the Microchip package drawing and consider via-in-pad or dog-bone fanout for the dense perimeter. Route JTAG (TCK/TMS/TDO/TDI) as a short, daisy-chained group with series resistors if multiple JTAG devices share the chain, and reserve unpopulated JTAG connector pads even on cost-reduced boards - boundary-scan ICT on 100-TQFP assemblies routinely pays back its 0.2 uF bypass cost in escaped-defect reduction.
Common mistakes: (1) assuming ATmega2560 is a drop-in - it shares the 100-TQFP count but NOT the pinout with the mega3250 family; (2) using the mega3290 (LCD variant) as a substitute without remapping the LCD-shared pins; (3) exceeding EEPROM endurance by writing calibration data in every loop iteration instead of on change. Also verify RESET pin pull-up and that ISP programming lines (MOSI/MISO/SCK/RESET) are not loaded heavily by peripheral circuits, or in-circuit programming will fail.
For EMC on appliances and industrial panels, add 10-33 ohm series resistors on long GPIO runs driving cables, and use the internal pull-ups on unused pins configured as inputs, or drive unused pins as outputs low, to prevent floating-node EMI emissions. Keep the USART/TWI clock lines short and, on TWI buses longer than 30 cm, size pull-up resistors (typically 2.2k-4.7k at 5 V) to meet rise-time requirements at 100-400 kHz.
Compliance Information
RoHS/lead-free per Microchip 'AU' (lead-free matte-tin) packaging convention for AVR parts. Lifecycle status ACTIVE per distributor and datasheet aggregator data. REACH/halogen/conflict-minerals declarations not present in verified data - request official compliance certificate from Microchip.
