ATMEGA161-8AI - 8MHz 16KB Flash AVR MCU 44-TQFP | Microchip
MPN: ATMEGA161-8AI ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.42 | $8.42 |
| 10 | $7.58 | $75.80 |
| 100 | $6.73 | $673.00 |
| 500 | $5.9 | $2,950.00 |
| 1,000 | $5.05 | $5,050.00 |
ATMEGA161-8AI Overview
A microcontroller unit (MCU) integrates a processor core, program memory, data memory, and peripherals on a single chip, sitting at the lowest level of the embedded-system hierarchy: semiconductor -> integrated circuit -> microcontroller -> application-specific embedded system. The AVR family popularized the modified Harvard RISC architecture with single-cycle instruction execution, in which the ATmega161 series was an early 16KB-class member designed as a successor to the AT90S4414/8515.
Key features of the ATMEGA161-8AI include the advanced AVR RISC core with 130 powerful instructions (most executed in a single clock cycle), 32 x 8 general-purpose working registers, and fully static operation. Program memory is 16KB of In-System Programmable Flash organized for boot-program operation, supported by 512 bytes of EEPROM and 1KB of internal SRAM. Two flexible 8-bit timer/counters with compare modes, one 16-bit timer/counter, and two UARTs provide rich peripheral integration for communication and timing tasks.
Architecturally, the device separates instruction and data buses (Harvard architecture), enabling one instruction per clock cycle and deterministic timing essential to real-time embedded control. The external oscillator drives core speeds up to 8MHz at 5V, and the -AI temperature grade (-40C to +85C, industrial) with green packaging suits harsh industrial environments.
Typical applications include industrial automation controllers, communications and networking nodes exploiting the dual UART, embedded instrumentation, and legacy equipment maintenance where ATmega161 firmware must be preserved. Designers should note this 5V-only family requires level translation in 3.3V systems; also plan ISP Flash programming infrastructure early, and verify lifecycle status since ATmega161 devices have largely been superseded by ATmega162 and ATmega16 derivatives. Choose the -8AI grade when -40C to +85C operation is required in TQFP-44.
This page synthesizes distributor pricing context, drop-in same-package alternatives, and practical design notes not found in the manufacturer datasheet, per verified web data as of 2026-09-16.
Drop-in alternatives for ATMEGA161-8AI — 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 ATMEGA161-8AI (same form factor and footprint) — differing in Package, Core Architecture, EEPROM, General Purpose Registers, Flash Memory.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA162-16AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.45 / Unit
View Datasheet →ATMEGA16-16AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$4.41 / Unit
View Datasheet →ATMEGA16-16AJ
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.1 / Unit
View Datasheet →ATMEGA161-8AC
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$7.95 / Unit
View Datasheet →AT90S8515-8AC
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
ATMEGA161-8AI Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Program Memory Size | 16KB (8K x 16) FLASH |
| SRAM Size | 1KB |
| Maximum Clock Frequency | 8MHz |
| Supply Voltage | 5V |
| Instruction Count | 130 powerful instructions |
| General Purpose Registers | 32 x 8-bit |
| Throughput | Up to 8 MIPS (most instructions single-cycle) |
| UART Channels | 2 |
| Operating Temperature | -40C to +85C (industrial, AI grade) |
| Package | 44-TQFP (10x10 mm) |
| Mounting Type | Surface Mount |
| Series | AVR ATmega161 |
| Oscillator Type | External |
ATMEGA161-8AI 44-tqfp (10x10 mm) Pin Configuration Guide
Pin configuration for ATMEGA161-8AI (44-tqfp (10x10 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 ATMEGA161-8AI.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA161-8AI is suitable for 6 applications: Industrial Automation Controllers, Dual-UART Communication Nodes, Legacy Equipment Maintenance and Repair, Embedded Instrumentation and Data Loggers, Building Automation and Access Control Panels, Motor Control and Embedded Power Subsystems.
Industrial Automation Controllers
The ATMEGA161-8AI fits industrial automation nodes because its -40C to +85C industrial grade, fully static AVR core, and deterministic single-cycle instruction execution support real-time control loops in PLC I/O modules and machine controllers. Operating at 5V and up to 8MHz (8 MIPS), it drives relay outputs, reads switches, and sequences actuators with three flexible timer/counters providing PWM and compare functions. In such systems it typically sits between field wiring protection and backplane communication; the dual UART lets one channel serve the fieldbus (e.g., RS-485) while the other handles local diagnostics. Its main trade-off versus newer parts is 5V-only I/O, which actually simplifies interfacing with legacy industrial 5V logic.
Recommended
Dual-UART Communication Nodes
With two independent hardware UARTs, the ATMEGA161-8AI is well suited to protocol gateways and communication nodes that bridge two serial buses - for example an RS-232 diagnostic port and an RS-485 fieldbus on the same MCU. At 8MHz, standard baud rates from 2400 upward run with low timing error from the 5V clock, and the 1KB SRAM provides buffering space for packet reassembly on both channels. Unlike software (bit-banged) UART implementations, the dual hardware UARTs maintain full-duplex throughput without stealing CPU cycles, keeping interrupt latency low for time-critical framing. Designers should include level translators (e.g., MAX232 or RS-485 transceivers) because the MCU I/O is 5V-only.
Recommended
Legacy Equipment Maintenance and Repair
For servicing obsolete ATmega161-based equipment - test instruments, industrial drives, or medical peripherals from the early 2000s - the ATMEGA161-8AI remains one of the few authentic replacement paths, since the 16KB Flash accepts the original firmware image bit-for-bit. Distributor stock (e.g., 4,176 pieces reported at Heisener) supports repair quantities. Using the genuine part avoids the register-level and timing differences encountered when porting old ATmega161 firmware to ATmega162 or ATmega16 successors, which can alter serial timing loops and interrupt-driven code. For repairs limited to 0C to +70C environments, the commercial -8AC variant offers the same die and footprint at lower cost.
Recommended
Embedded Instrumentation and Data Loggers
The ATMEGA161-8AI serves compact measurement instruments that need to sample sensors, timestamp readings, and stream results over serial links. The 16-bit timer/counter provides precise timebases for frequency and period measurement, while the two UARTs simultaneously feed a local display or printer and a remote host. With 1KB of SRAM, typical logging applications hold ring buffers of hundreds of samples between transmissions, and the 512-byte-class EEPROM path supports calibration constants persisting across power cycles. Because the AVR core is fully static, clocking the device below 8MHz in battery-operated instruments reduces dynamic power roughly proportionally - a useful energy trade-off versus duty-cycling.
Recommended
Building Automation and Access Control Panels
Access-control readers and small building-automation panels benefit from the ATMEGA161-8AI's combination of industrial temperature rating, dual UARTs (one for a Wiegand/RS-485 network, one for a printer or modem), and five-volt I/O directly driving LEDs, buzzers, and relay drivers. Timer/counters generate keypad-scan interrupts and door-strike timing without CPU overhead, while the 16KB Flash accommodates protocol stacks plus local blacklists in code space. The 44-TQFP surface-mount footprint suits compact wall-panel PCBs, and the -40C to +85C grade covers unheated outdoor reader enclosures. Level-shifting is required when connecting modern 3.3V RFID front ends to the 5V MCU ports.
Recommended
Motor Control and Embedded Power Subsystems
Small motor controllers - fans, pumps, conveyors, and stepper drivers - can use the ATMEGA161-8AI's three timer/counters to generate PWM drive signals while the RISC core handles current-loop feedback and fault supervision at up to 8 MIPS. Deterministic single-cycle execution keeps control-loop jitter low, and the industrial temperature grade matches cabinet environments. A typical architecture pairs the MCU with a gate-driver and power stage: the MCU outputs PWM plus direction signals, reads hall or encoder feedback on its ports, and reports status over one UART while the second UART accepts host commands. Note the device has no hardware quadrature decoder, so encoder counting runs in software interrupts.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA161-8AI — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA162-16AU | ATMEGA16-16AU | ATMEGA16-16AJ | ATMEGA161-8AC | AT90S8515-8AC |
|---|---|---|---|---|---|---|
| Package | 44-TQFP (10x10 mm) | 44-TQFP (10x10 mm) - same | 44-TQFP (10x10 mm) - same | 44-TQFP (10x10 mm) - same | 44-TQFP (10x10 mm) - same | 44-TQFP (10x10 mm) - same |
| Brand | Microchip Technology (originally Atmel) | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 16KB (8K x 16) | 16KB | 16KB | 16KB | 16KB | 8KB |
| Max Clock Frequency | 8MHz | 16MHz | 16MHz | 16MHz | 8MHz | 8MHz |
| UART Channels | 2 | 2 | 1 | 1 | 2 | 1 |
| On-chip ADC | No | No | Yes (8ch, 10-bit) | Yes (8ch, 10-bit) | No | No |
| Operating Temperature | -40C to +85C (industrial) | -40C to +85C | -40C to +85C | -40C to +85C | 0C to +70C (commercial) | 0C to +70C (commercial) |
| Lifecycle Status | EOL generation | Active | Active | Active | EOL generation | Obsolete |
Key Differentiators
- Dual hardware UARTs (vs ATMEGA16-16AU)
- Industrial temperature grade (vs ATMEGA161-8AC)
- Legacy firmware compatibility (vs ATMEGA162-16AU)
- Honest trade-off: no on-chip ADC (vs ATMEGA16-16AU)
Design Notes
The ATMEGA161-8AI is a 5V-only device. Place 100nF ceramic decoupling capacitors at each of the two VCC/GND pin pairs within 5mm of the pins, plus a 10uF bulk capacitor near the supply entry. When interfacing 3.3V peripherals, add proper level translation (e.g., BSS138-based bidirectional shifters or TXS0108E) on all GPIO, UART, and ISP lines; directly mixing 3.3V open-drain buses with a 5V AVR risks overvoltage on the slave device. Estimated: at 8MHz and 5V, active-mode current is in the low-milliamp class per AVR family typicals - verify exact ICC against the datasheet for your thermal budget.
For the 44-TQFP (10x10 mm, 0.8mm pitch) footprint, use a standard 0.65mm-wide pad per IPC-7351-class TQFP land patterns and route the RESET line short with a 10k pullup to support ISP programming - include a 6-pin ISP header (MOSI, MISO, SCK, RESET, VCC, GND) on every production board for field firmware updates. Keep the external oscillator crystal within 10mm of XTAL1/XTAL2 with ground guard traces, since the AVR oscillator input is sensitive to stray capacitance at 8MHz.
The most common ATmega161 migration error is assuming pinout identity with ATmega16 or ATmega162: although the ATmega162 is the pin-compatible successor, the ATmega16 has peripheral-driven multiplexing differences (ADC pins replace UART1 functions) that can break dual-UART boards. Also verify firmware porting: interrupt vector tables and register names differ between ATmega161 and ATmega162, so recompile and retest serial timing loops rather than reusing binaries. Finally, confirm RoHS certification for the exact -AI suffix with your distributor, since this generation predates uniform green packaging.
Compliance Information
Compliance data for the exact ATMEGA161-8AI suffix was not found in the verified web data. Older Atmel AVR parts in this generation predate uniform RoHS requalification - request certificates from the distributor.
