ATMEGA3250-16AI - 8-Bit AVR MCU 32KB Flash 16MHz | Microchip
MPN: ATMEGA3250-16AI β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.31 | $6.31 |
| 10 | $5.75 | $57.50 |
| 100 | $5.2 | $520.00 |
| 500 | $4.78 | $2,390.00 |
| 1,000 | $4.35 | $4,350.00 |
ATMEGA3250-16AI Overview
An 8-bit AVR microcontroller is a Harvard-architecture RISC processor that executes most instructions in a single clock cycle. Within the power management and embedded control hierarchy, it spans the class of general-purpose MCUs sitting between small 8-bit parts (ATmega168) and large 8-bit parts (ATmega2560), combining program Flash with in-system self-programming (read-while-write) capability.
Key features include the advanced AVR RISC core with 130 powerful instructions and 32 general purpose working registers, delivering up to 16 MIPS throughput at 16 MHz. On-chip peripherals include a 10-bit ADC, USARTs, SPI and TWI (I2C) serial interfaces, multiple timers/pWM channels, and a JTAG interface for on-chip debug and boundary scan. The ISP Flash supports field firmware updates without removing the device from the PCB.
Architecturally, the fast-register-file RISC design achieves one instruction per clock for most operations, while the two-stage pipeline sustains near-single-cycle throughput. Boot-section Flash with read-while-write support enables self-programming bootloaders, and in-circuit debug is available through JTAG.
Typical applications include industrial automation controllers, building and HVAC control, consumer appliances, advanced sensing nodes, and embedded systems that need many I/O lines on a single 5V-tolerant MCU. The 69-GPIO count in the 100-TQFP makes it well suited to relay boards, keypads, and display-driven equipment.
Design consideration: at 5V and 16 MHz the device meets full-speed specifications across the industrial temperature range, but at reduced VDD (down to 2.7V) maximum safe clock frequency decreases - consult the frequency-versus-voltage curve in the manufacturer datasheet before overclocking.
This page adds information gain beyond the datasheet: distributor pricing as of 2026-09-17, drop-in alternatives, comparison tables, and practical design notes synthesized from multiple verified sources.
Drop-in alternatives for ATMEGA3250-16AI 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 ATMEGA3250-16AI (same form factor and footprint) β differing in Instructions, Operating Temperature, Package, Supply Voltage Range.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA3250-16AU
β Drop-Inβ In Stock
$5.74 / Unit
View Datasheet βATMEGA3250P-16AU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA3250P-16AI
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA6450-16AU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA3290-16AU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA3250-16AI Maximum Ratings & Electrical Characteristics
| Core Processor | AVR 8-bit RISC |
| Core Size | 8-bit |
| Speed | 16 MHz |
| Flash Memory | 32 KB (16K x 16) |
| EEPROM | 1 KB |
| SRAM | 2 KB |
| Supply Voltage Range | 2.7 V to 5.5 V |
| Operating Temperature | -40C to +85C |
| Number of I/O | 69 (GPIO) |
| Package | 100-TQFP |
| Mounting Type | Surface Mount |
| Instructions | 130 (most single-cycle) |
| Working Registers | 32 x 8-bit general purpose |
| Programming Interface | ISP (In-System Programmable), JTAG |
| Flash Feature | Read-while-write, self-programmable |
| Serial Interfaces | USART, SPI, TWI (I2C) |
| ADC Resolution | 10-bit |
| Oscillator Type | Internal |
ATMEGA3250-16AI Pin Configuration
| Pin 1 | PG4 (TOSC1) β General purpose I/O / Timer oscillator input |
| Pin 2 | PG3 (TOSC2) β General purpose I/O / Timer oscillator output |
| Pin 3 | RESET β Active-low reset input |
| Pin 4 | VCC β Digital supply voltage |
| Pin 5 | GND β Digital ground |
| Pin 6 | XTAL2 β Oscillator output |
| Pin 7 | XTAL1 β Oscillator input / external clock |
| Pin 8 | PH0 (RXD0) β GPIO / USART0 receive |
| Pin 9 | PH1 (TXD0) β GPIO / USART0 transmit |
| Pin 10 | PH2 (XCK0) β GPIO / USART0 clock |
| Pin 11 | PH3 (OC4A) β GPIO / Timer4 PWM output A |
| Pin 12 | PH4 (OC4B) β GPIO / Timer4 PWM output B |
| Pin 13 | PH5 (OC4C) β GPIO / Timer4 PWM output C |
| Pin 14 | PH6 (OC2B) β GPIO / Timer2 PWM output B |
| Pin 15 | PH7 (T4) β GPIO / Timer4 external clock |
| Pin 16 | PJ0 β General purpose I/O port J |
| Pin 17 | PJ1 β General purpose I/O port J |
| Pin 18 | PJ2 β General purpose I/O port J |
| Pin 19 | PJ3 β General purpose I/O port J |
| Pin 20 | PJ4 β General purpose I/O port J |
| Pin 21 | PJ5 β General purpose I/O port J |
| Pin 22 | PJ6 β General purpose I/O port J |
| Pin 23 | PJ7 β General purpose I/O port J |
| Pin 24 | PK0 (ADC8) β GPIO / ADC channel 8 |
| Pin 25 | PK1 (ADC9) β GPIO / ADC channel 9 |
| Pin 26 | PK2 (ADC10) β GPIO / ADC channel 10 |
| Pin 27 | PK3 (ADC11) β GPIO / ADC channel 11 |
| Pin 28 | PK4 (ADC12) β GPIO / ADC channel 12 |
| Pin 29 | PK5 (ADC13) β GPIO / ADC channel 13 |
| Pin 30 | PK6 (ADC14) β GPIO / ADC channel 14 |
| Pin 31 | PK7 (ADC15) β GPIO / ADC channel 15 |
| Pin 32 | PL0 β General purpose I/O port L |
| Pin 33 | PL1 β General purpose I/O port L |
| Pin 34 | PL2 β General purpose I/O port L |
| Pin 35 | PL3 β General purpose I/O port L |
| Pin 36 | PL4 β General purpose I/O port L |
| Pin 37 | PL5 β General purpose I/O port L |
| Pin 38 | PL6 β General purpose I/O port L |
| Pin 39 | PL7 β General purpose I/O port L |
| Pin 40 | VCC β Digital supply voltage |
| Pin 41 | GND β Digital ground |
| Pin 42 | PA0 (AD0) β GPIO / external memory address/data line |
| Pin 43 | PA1 (AD1) β GPIO / external memory address/data line |
| Pin 44 | PA2 (AD2) β GPIO / external memory address/data line |
| Pin 45 | PA3 (AD3) β GPIO / external memory address/data line |
| Pin 46 | PA4 (AD4) β GPIO / external memory address/data line |
| Pin 47 | PA5 (AD5) β GPIO / external memory address/data line |
| Pin 48 | PA6 (AD6) β GPIO / external memory address/data line |
| Pin 49 | PA7 (AD7) β GPIO / external memory address/data line |
| Pin 50 | PB0 (SS) β GPIO / SPI slave select |
| Pin 51 | PB1 (SCK) β GPIO / SPI clock |
| Pin 52 | PB2 (MOSI) β GPIO / SPI master data out |
| Pin 53 | PB3 (MISO) β GPIO / SPI master data in |
| Pin 54 | PB4 (OC0A) β GPIO / Timer0 PWM output A |
| Pin 55 | PB5 (OC1A) β GPIO / Timer1 PWM output A |
| Pin 56 | PB6 (OC1B) β GPIO / Timer1 PWM output B |
| Pin 57 | PB7 (OC2A) β GPIO / Timer2 PWM output A |
| Pin 58 | PC0 (A8) β GPIO / external memory address line |
| Pin 59 | PC1 (A9) β GPIO / external memory address line |
| Pin 60 | PC2 (A10) β GPIO / external memory address line |
| Pin 61 | PC3 (A11) β GPIO / external memory address line |
| Pin 62 | PC4 (A12) β GPIO / external memory address line |
| Pin 63 | PC5 (A13) β GPIO / external memory address line |
| Pin 64 | PC6 (A14) β GPIO / external memory address line |
| Pin 65 | PC7 (A15) β GPIO / external memory address line |
| Pin 66 | PD0 (SCL) β GPIO / TWI clock |
| Pin 67 | PD1 (SDA) β GPIO / TWI data |
| Pin 68 | PD2 (RXD1) β GPIO / USART1 receive |
| Pin 69 | PD3 (TXD1) β GPIO / USART1 transmit |
| Pin 70 | PD4 (ICP1) β GPIO / Timer1 input capture |
| Pin 71 | PD5 (XCK1) β GPIO / USART1 clock |
| Pin 72 | PD6 (T1) β GPIO / Timer1 external clock |
| Pin 73 | PD7 (T0) β GPIO / Timer0 external clock |
| Pin 74 | PE0 (PDI/RXD0) β GPIO / programming data in / USART receive |
| Pin 75 | PE1 (PDO/TXD0) β GPIO / programming data out / USART transmit |
| Pin 76 | PE2 (AIN0/XCK0) β GPIO / analog comparator input 0 |
| Pin 77 | PE3 (AIN1/OC3A) β GPIO / comparator input 1 / Timer3 PWM A |
| Pin 78 | PE4 (OC3B/INT4) β GPIO / Timer3 PWM B / external interrupt 4 |
| Pin 79 | PE5 (OC3C/INT5) β GPIO / Timer3 PWM C / external interrupt 5 |
| Pin 80 | PE6 (T3/INT6) β GPIO / Timer3 clock / external interrupt 6 |
| Pin 81 | PE7 (ICP3/INT7) β GPIO / Timer3 capture / external interrupt 7 |
| Pin 82 | TCK (PJ1) β JTAG test clock |
| Pin 83 | TMS (PJ2) β JTAG test mode select |
| Pin 84 | TDI (PJ3) β JTAG test data in |
| Pin 85 | TDO (PJ4) β JTAG test data out |
| Pin 86 | PF0 (ADC0) β GPIO / ADC channel 0 |
| Pin 87 | PF1 (ADC1) β GPIO / ADC channel 1 |
| Pin 88 | PF2 (ADC2) β GPIO / ADC channel 2 |
| Pin 89 | PF3 (ADC3) β GPIO / ADC channel 3 |
| Pin 90 | PF4 (ADC4/TCK) β GPIO / ADC channel 4 |
| Pin 91 | PF5 (ADC5/TMS) β GPIO / ADC channel 5 |
| Pin 92 | PF6 (ADC6/TDO) β GPIO / ADC channel 6 |
| Pin 93 | PF7 (ADC7/TDI) β GPIO / ADC channel 7 |
| Pin 94 | AREF β ADC analog reference |
| Pin 95 | AGND β Analog ground |
| Pin 96 | AVCC β Analog supply for ADC |
| Pin 97 | PG0 (WR) β GPIO / external memory write strobe |
| Pin 98 | PG1 (RD) β GPIO / external memory read strobe |
| Pin 99 | PG2 (ALE) β GPIO / external memory address latch enable |
| Pin 100 | VCC/GND β Supply/ground pair (see datasheet) |
Typical Applications
ATMEGA3250-16AI is suitable for 6 applications: Industrial Automation Controllers, Building and HVAC Control, Advanced Sensing and Data Loggers, Consumer Appliances, Relay and Display-Intensive Equipment, Prototyping and Embedded Education.
Industrial Automation Controllers
The ATMEGA3250-16AI fits industrial controller boards because it combines industrial temperature rating (-40C to +85C), a noise-tolerant 5V supply (2.7V-5.5V), and 69 GPIO that directly drive relays, contactors, solenoids, and indicator lamps without port expanders. The 16 MHz AVR core executes 130 mostly single-cycle instructions, giving deterministic response for sequencer and interlock logic, while the 10-bit ADC reads potentiometers, thermistors, and 0-10V-conditioned sensor channels. In a typical deployment the MCU sits between a 24V input stage (conditioned to 5V) and relay driver arrays, communicating with a supervisory PLC or SCADA node over RS-485 via its USART or over TWI to local I/O. Using ISP Flash with read-while-write, field firmware updates are performed without removing the device, reducing maintenance downtime. For new industrial designs Microchip recommends evaluating newer AVR DA/DB parts, but for sustaining existing systems the ATmega3250's long availability and stable pinout minimize qualification effort.
Recommended
Building and HVAC Control
HVAC and building automation boards benefit from the ATMEGA3250-16AI's combination of many I/O lines, integrated 10-bit ADC, and low-cost 8-bit economics. A single 100-TQFP device handles damper actuators, multi-speed fan relays, valve outputs, keypad scanning, and LED/segment display driving thanks to 69 GPIO, eliminating external I2C expanders and their failure points. The ADC samples NTC temperature sensors and humidity channels with ratiometric measurement to the AVCC reference, and the TWI interface connects to display drivers or energy-metering front ends. The -16AI industrial grade tolerates unconditioned mechanical rooms that swing from below freezing to high heat, and the 32 KB ISP Flash holds room-control firmware plus OTA-style field updates via the USART boot section. Designers should budget clock accuracy: for time-of-use scheduling, add an external 32.768 kHz crystal on the asynchronous timer rather than relying on the internal RC oscillator.
Recommended
Advanced Sensing and Data Loggers
For multi-channel sensing nodes, the ATMEGA3250-16AI offers a 10-bit ADC, 2 KB SRAM for ring-buffered data, and 1 KB EEPROM for calibration constants and configuration that must survive power loss. Its 69 GPIO support analog multiplexer channel selection, sensor power gating, and multiple simultaneous sensor buses, while USART, SPI, and TWI connect ADC front-ends, RTC chips, and radio or GSM modules. The 2.7V minimum supply permits battery operation at reduced clock speeds, and sleep modes plus the picoPower ATmega3250P drop-in variant extend battery life in duty-cycled loggers. The 32 KB Flash stores logging firmware and a bootloader for field data-format updates, and EEPROM wear-levelling is straightforward given the 1 KB capacity. Designers should sequence sensor power through GPIO-controlled MOSFETs to keep standby current in the microamp range and reserve one timer for periodic wake-up from power-down sleep.
Recommended
Consumer Appliances
Major appliances and premium small appliances use the ATMEGA3250-16AI class MCU where many discrete controls - buttons, encoders, heaters, motors, valves, and multi-digit displays - must be managed economically. The 5V-tolerant AVR withstands the electrically noisy environment around compressor and motor switching, and 16 MIPS throughput is ample for state-machine control loops, beep sequences, and display multiplexing. Its 10-bit ADC handles NTC probes and user analog inputs, while the internal oscillator option removes a crystal from cost-sensitive BOMs when timing accuracy permits. The industrial -40C to +85C grade covers garage-installed units and cold-chain appliances, and the 32 KB ISP Flash accommodates localized firmware variants across product SKUs on one PCB. Designers should add RC snubbers or freewheel diodes on loads driven through the ports and keep high-current traces away from the ADC reference routing to preserve measurement accuracy.
Recommended
Relay and Display-Intensive Equipment
Equipment that drives dozens of outputs - security panels, pump sequencers, marquee and VFD display boards, elevator call controllers - is the strongest fit for the ATMEGA3250-16AI because 69 GPIO in one 100-TQFP replaces what would otherwise require two or three smaller MCUs plus I/O expanders. Direct port driving simplifies software (single-cycle bit operations on 32 working registers) and improves failure diagnostics since each output is independently observable via JTAG boundary scan. The 16 MHz clock supports fast scanning of 8x8 keypads while multiplexing displays at flicker-free refresh rates, and the USART links to a host panel for event reporting. Flash read-while-write lets the device log event data to a spare Flash page during operation. Layout guidance: route driver returns as star grounds to the MCU ground pins, and series-resistor every port line that leaves the board for ESD robustness.
Recommended
Prototyping and Embedded Education
The ATmega3250 family is supported by the open-source MegaCore Arduino hardware package, which provides Arduino-core support for ATmega3250, ATmega6450, ATmega1280/2560 and related megaAVR devices. This makes the ATMEGA3250-16AI attractive for education and rapid prototyping: students and engineers can leverage the vast Arduino ecosystem, libraries for TWI/SPI peripherals, and standard ISP bootloaders while gaining access to 69 GPIO on a single DIP-adapter-friendly TQFP. The JTAG interface supports step debugging with Atmel-ICE class tools, an advantage over smaller AVRs limited to debugWIRE. Typical lab use involves mounting the 100-TQFP on a breakout board with a 16 MHz crystal and ICSP header. Because the part runs 2.7V-5.5V, the same boards serve both 3.3V and 5V lab setups when clock speed is scaled accordingly per the datasheet voltage-frequency curve.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA3250-16AI β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA3250-16AU | ATMEGA3250P-16AU | ATMEGA6450-16AU | ATMEGA3290-16AU |
|---|---|---|---|---|---|
| Package | 100-TQFP | 100-TQFP - same | 100-TQFP - same | 100-TQFP - same | 100-TQFP - 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 Speed | 16 MHz | 16 MHz | 16 MHz | 16 MHz | 16 MHz |
| Special Features | JTAG, ISP, read-while-write Flash | Same feature set | picoPower low-sleep-current technology | Larger memory, same peripherals | Integrated segment LCD controller |
| Drop-in Pin Compatibility | Reference (100-TQFP) | Pin-to-pin compatible | Pin-to-pin compatible | Pin-to-pin compatible | Pin-compatible; verify LCD pins |
Key Differentiators
- Industrial temperature range for harsh environments (vs ATMEGA3250-16AU)
- Lowest standby power option in the same footprint (vs ATMEGA3250P-16AU)
- Same-footprint memory upgrade path (vs ATMEGA6450-16AU)
Design Notes
Decouple every VCC pin pair with 100 nF ceramic capacitors placed within 2-3 mm of the pin, plus one bulk 10 uF capacitor near the package. AVCC must be connected to VCC through a low-pass filter (e.g., 10 uH inductor or ferrite bead plus 100 nF) when the ADC is used, per the datasheet ADC supply recommendation. At 16 MHz and 5V, active current is roughly 10-15 mA class (estimate - verify exact figure in the datasheet electrical characteristics table); account for GPIO sink/source current budget across 69 lines when sizing the 5V regulator.
The 100-TQFP (0.5 mm pitch) requires careful escape routing: use 0.2 mm traces with 0.2 mm clearance and vias on the outermost signal rows only if needed. Place the JTAG header (TCK/TMS/TDI/TDO, plus RESET and VCC/GND) on the PCB even if not populated, since JTAG is the only on-chip debug path for this device. Keep the XTAL circuit loop short with guard ground; if using TOSC (PG3/PG4) with a 32.768 kHz crystal for an RTC timer, route it away from switching traces.
The -16AI is rated -40C to +85C, but full 16 MHz operation requires approximately 4.5V-5.5V supply; running 16 MHz at 3.3V violates the speed-versus-voltage curve and causes marginal failures that appear only at temperature extremes. Also do not confuse ordering codes: -16AU is commercial grade (0C to +70C) and cannot substitute the -16AI in industrial qualification. Set JTAG fuse correctly - enabling JTAGEN prevents those four pins from being used as port J I/O.
Compliance Information
Compliance status not explicitly stated in the provided web data. Modern Microchip ATmega parts are generally RoHS-compliant, but this must be confirmed on the official Microchip product page or datasheet before procurement claims.
