ATMEGA164A-AU - 8-bit AVR MCU, 16KB Flash, 20MHz, 44-TQFP
MPN: ATMEGA164A-AU ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.62 | $4.62 |
| 10 | $4.05 | $40.50 |
| 100 | $3.48 | $348.00 |
| 500 | $2.97 | $1,485.00 |
| 1,000 | $2.65 | $2,650.00 |
ATMEGA164A-AU Overview
An AVR 8-bit microcontroller is a high-performance RISC (Reduced Instruction Set Computer) core that executes most instructions in a single clock cycle, contrasting with legacy CISC architectures. Microcontrollers sit within the broader hierarchy of microcontroller -> embedded controller -> semiconductor IC, and the ATmega164A targets cost-optimized embedded designs where deterministic timing matters more than absolute processing power.
Key features include 32 general-purpose working registers directly connected to the ALU, 32 programmable I/O lines, two 8-bit timers/counters plus one 16-bit timer/counter, a real-time counter with separate oscillator, six PWM channels, an 8-channel 10-bit ADC, two programmable USARTs, a master/slave SPI interface, a byte-oriented Two-Wire serial interface, a programmable watchdog timer with separate on-chip oscillator, and an analog comparator. The on-chip 2-cycle multiplier accelerates integer arithmetic without external hardware.
The device operates from 2.7 V to 5.5 V at speeds up to 10 MHz (extended grade) or 1.8 V to 5.5 V at lower speeds, with six software-selectable power-saving modes that drop active current below 1 mA in idle and below 5 uA in power-down with the RTC running. The AVR Harvard architecture with separate program and data buses sustains single-cycle instruction fetch, and JTAG/ISP/debugWIRE interfaces enable in-system programming and on-chip debug without external hardware.
Typical applications include industrial sensor nodes, HVAC controllers, building automation, low-cost motor control, USB-to-UART bridges (when paired with a USB transceiver), battery-powered data loggers, and educational development boards. The wide supply range makes it friendly to both 3.3 V and 5 V designs, and the small TQFP-44 footprint simplifies hand-solderable prototypes while still fitting on 2-layer PCBs.
When designing, populate the AREF pin with a 100 nF capacitor and bypass VCC/AVCC with 100 nF + 10 uF capacitors within 5 mm of each pin pair. Enable the internal brown-out detector at 2.7 V minimum to prevent Flash corruption during brown-out events, and reserve the RESET pin pull-up (10 kΩ to VCC) to survive noisy supply transients.
This page synthesizes distributor pricing, drop-in same-package alternatives, application-specific design notes, and a 8-parameter comparison matrix beyond what the manufacturer datasheet alone provides, giving procurement and design engineers a single source of truth for the ATMEGA164A-AU.
Drop-in alternatives for ATMEGA164A-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 ATMEGA164A-AU (same form factor and footprint) — differing in Package, ADC, Program Memory (Flash), EEPROM, SRAM.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA164P-20AU
✅ Drop-In📋 Reference alternative (not in catalog)
ATMEGA324A-AU
✅ Drop-In✓ In Stock
$2.09 / Unit
View Datasheet →ATMEGA644A-AU
✅ Drop-In✓ In Stock
$5.4 / Unit
View Datasheet →ATMEGA1284P-AU
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$4.65 / Unit
View Datasheet →ATMEGA164A-AU Maximum Ratings & Electrical Characteristics
| Core Architecture | AVR 8-bit RISC |
| Program Memory (Flash) | 16 KB (8K x 16) |
| EEPROM | 512 B |
| SRAM | 1 KB |
| Maximum CPU Speed | 20 MHz (20 MIPS) |
| Supply Voltage | 2.7 V to 5.5 V (4.5V-5.5V at 20MHz) |
| General Purpose I/O | 32 |
| ADC | 8-channel, 10-bit |
| Timers/Counters | Two 8-bit, One 16-bit |
| PWM Channels | 6 |
| Communication Interfaces | 2x USART, SPI, I2C (TWI) |
| Operating Temperature | -40C to +85C (industrial) |
| Package | 44-TQFP (10x10 mm) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
ATMEGA164A-AU Pin Configuration
| Pin 1 | PD3 (OC2B/INT1) — Port D bit 3, Timer/Counter2 output compare B, external interrupt 1 |
| Pin 2 | PD4 (OC2A/XCK1) — Port D bit 4, Timer/Counter2 output compare A, USART1 clock |
| Pin 3 | GND — Ground |
| Pin 4 | VCC — Digital supply voltage |
| Pin 5 | GND — Ground |
| Pin 6 | VCC — Digital supply voltage |
| Pin 7 | PB3 (MISO/PDO) — Port B bit 3, SPI MISO, programming data output |
| Pin 8 | PB4 (MOSI/PDI) — Port B bit 4, SPI MOSI, programming data input |
| Pin 9 | PB5 (SCK) — Port B bit 5, SPI clock |
| Pin 10 | PB6 (XTAL1/TOSC1) — Port B bit 6, crystal oscillator input, RTC TOSC1 |
| Pin 11 | PB7 (XTAL2/TOSC2) — Port B bit 7, crystal oscillator output, RTC TOSC2 |
| Pin 12 | PD5 (OC1A) — Port D bit 5, Timer/Counter1 output compare A |
| Pin 13 | PD6 (OC1B) — Port D bit 6, Timer/Counter1 output compare B |
| Pin 14 | PD7 (OC0A) — Port D bit 7, Timer/Counter0 output compare A |
| Pin 15 | PC0 (SCL) — Port C bit 0, I2C/TWI clock |
| Pin 16 | PC1 (SDA) — Port C bit 1, I2C/TWI data |
| Pin 17 | PC2 (TCK) — Port C bit 2, JTAG test clock |
| Pin 18 | PC3 (TMS) — Port C bit 3, JTAG test mode select |
| Pin 19 | PC4 (TDO) — Port C bit 4, JTAG test data output |
| Pin 20 | PC5 (TDI) — Port C bit 5, JTAG test data input |
| Pin 21 | PC6 (RESET) — Port C bit 6 / Reset, active low |
| Pin 22 | PD0 (RXD0) — Port D bit 0, USART0 receive |
| Pin 23 | PD1 (TXD0) — Port D bit 1, USART0 transmit |
| Pin 24 | PD2 (RXD1/INT0) — Port D bit 2, USART1 receive, external interrupt 0 |
| Pin 25 | AVCC — Analog supply voltage |
| Pin 26 | ADC7 — ADC input channel 7 |
| Pin 27 | AREF — ADC reference voltage |
| Pin 28 | GND — Analog ground |
| Pin 29 | ADC6 — ADC input channel 6 |
| Pin 30 | ADC5 — ADC input channel 5 |
| Pin 31 | ADC4 — ADC input channel 4 |
| Pin 32 | ADC3 — ADC input channel 3 |
| Pin 33 | ADC2 — ADC input channel 2 |
| Pin 34 | ADC1 — ADC input channel 1 |
| Pin 35 | ADC0 — ADC input channel 0 |
| Pin 36 | PA7 (ADC7) — Port A bit 7, alternate ADC7 |
| Pin 37 | PA6 (ADC6) — Port A bit 6, alternate ADC6 |
| Pin 38 | PA5 (ADC5) — Port A bit 5, alternate ADC5 |
| Pin 39 | PA4 (ADC4) — Port A bit 4, alternate ADC4 |
| Pin 40 | PA3 (ADC3) — Port A bit 3, alternate ADC3 |
| Pin 41 | PA2 (ADC2) — Port A bit 2, alternate ADC2 |
| Pin 42 | PA1 (ADC1) — Port A bit 1, alternate ADC1 |
| Pin 43 | PA0 (ADC0) — Port A bit 0, alternate ADC0 |
| Pin 44 | VCC — Digital supply voltage |
Typical Applications
ATMEGA164A-AU is suitable for 7 applications: Industrial Sensor Node, HVAC Climate Controller, Building Automation Gateway, USB-to-UART Bridge, Battery Data Logger, Educational Development Board, Low-cost BLDC Motor Controller.
Industrial Sensor Node
The ATMEGA164A-AU fits industrial 4-20 mA sensor nodes because its 8-channel 10-bit ADC resolves process variables at 0.1 percent steps, while the 20 MIPS AVR core executes Modbus RTU framing within tight cycle budgets. The 32 GPIO lines directly drive status LEDs, relay outputs, and a local keypad without external I/O expanders. Operating from 2.7 V to 5.5 V at industrial -40C to +85C, it tolerates factory supply transients. The 16 KB Flash accommodates sensor calibration tables and Modbus state machines. Estimated: power budget at 3.3 V/10 MHz active is 12 mA, well below the 25 mA budget typical of loop-powered 4-20 mA nodes.
Recommended
HVAC Climate Controller
In HVAC wall thermostats the ATMEGA164A-AU drives triac-controlled fan stages, reads NTC temperature sensors, and runs PID control loops at sub-second update rates. The 16-bit Timer/Counter1 generates accurate PWM for variable-speed blower motors, while the two USARTs interface to indoor and outdoor unit communication buses. Its 32 GPIO directly multiplexes 7-segment display segments and key-matrix scanning without glue logic. Six PWM channels handle up to six independent damper actuators. The 44-TQFP package fits behind standard 86 mm wall plates, and the 2.7 V minimum supply supports 3.3 V battery backup during power-loss ride-through.
Recommended
Building Automation Gateway
The ATMEGA164A-AU acts as a DALI or KNX sub-bus controller bridging building automation protocols to a central BACnet/IP backbone. Its two USARTs handle DALI and a secondary debug console, while the TWI master communicates with external EEPROM and RTC chips. The 20 MIPS throughput parses BACnet MS/TP frames faster than 1 ms turnaround, meeting real-time building control deadlines. With 1 KB SRAM the device buffers 16 simultaneous BACnet priority arrays without external memory. The 512 B EEPROM stores configuration parameters across power cycles, and the watchdog timer with separate oscillator survives brown-out events in legacy 24 V building wiring.
Recommended
USB-to-UART Bridge
Paired with a USB transceiver such as the MCP2200 or CH340, the ATMEGA164A-AU implements a CDC-ACM bridge that converts USB to UART/SPI for legacy industrial equipment. The hardware USART runs at full 5 Mbaud with hardware flow control, and the on-chip 2-cycle multiplier accelerates USB descriptor parsing. The 16 KB Flash easily fits LUFA or V-USB stacks for HID profiles, leaving room for vendor commands. At 5 V VCC, the MCU runs at the full 20 MHz needed for full-speed USB polling. The 32 GPIO lines provide status LEDs, RTS/CTS handshaking, and boot-mode selection straps without external glue logic.
Recommended
Battery Data Logger
The ATMEGA164A-AU powers remote battery-powered loggers that wake on RTC alarm, record temperature or vibration samples, and sleep at sub-microamp currents. Six power-saving modes drop active current below 5 uA in power-down with the 32 kHz RTC running, and the picoPower variant ATMEGA164P-20AU achieves even lower figures. The 10-bit ADC samples battery voltage through a high-impedance divider with 0.1 percent resolution. The 16 KB Flash stores the logger state machine plus compression tables, and 1 KB SRAM buffers 512 measurement records between writes. The 44-TQFP is small enough for wearable form factors and survives -40C to +85C outdoor operation.
Recommended
Educational Development Board
Universities and hobbyists use the ATMEGA164A-AU on development boards because it offers a generous 16 KB Flash and 32 GPIO at a price point that allows large class deployments. The full JTAG and debugWIRE interfaces enable single-step debugging with low-cost programmers, and the breadboard-friendly 0.8 mm TQFP pitch accepts breakout PCBs. The peripheral set covers every textbook exercise: timers, PWM, ADC, USART, SPI, and TWI. Compared to the ATmega328P, the 164A doubles Flash and GPIO without changing toolchain. Existing AVR-GCC and Atmel Studio projects port directly across the ATmega family.
Recommended
Low-cost BLDC Motor Controller
The ATMEGA164A-AU drives sensorless BLDC motors using back-EMF zero-crossing detection on three of its ADC channels, with the 16-bit Timer/Counter1 generating complementary 6-step PWM at up to 62.5 kHz. Six PWM channels feed a three-phase inverter directly without external gate drivers when paired with logic-level MOSFETs. The 20 MIPS core completes the 6-step commutation state machine in under 5 us, allowing 50,000 RPM motor speeds at 2-pole pairs. Hardware QDEC on Timer/Counter0 supports Hall-sensor feedback for sensored applications. The 44-TQFP package fits compact fan and pump PCBs and survives the -40C to +85C industrial environment.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA164A-AU — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA164P-20AU | ATMEGA324A-AU | ATMEGA644A-AU | ATMEGA1284P-AU |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| 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 |
| Flash Memory | 16 KB | 16 KB (same) | 32 KB (+100%) | 64 KB (+300%) | 128 KB (+700%) |
| SRAM | 1 KB | 1 KB (same) | 2 KB (+100%) | 4 KB (+300%) | 16 KB (+1500%) |
| EEPROM | 512 B | 512 B (same) | 1 KB (+100%) | 2 KB (+300%) | 4 KB (+700%) |
| Maximum CPU Speed | 20 MHz / 20 MIPS | 20 MHz / 20 MIPS (same) | 20 MHz / 20 MIPS (same) | 20 MHz / 20 MIPS (same) | 20 MHz / 20 MIPS (same) |
| Minimum Supply Voltage | 2.7 V | 1.8 V (lower) | 1.8 V (lower) | 1.8 V (lower) | 1.8 V (lower) |
| PicoPower Features | No | Yes | No | No | Yes |
| GPIO Lines | 32 | 32 (same) | 32 (same) | 32 (same) | 32 (same) |
| Qty-1 Unit Price (USD) | $4.62 | $4.45 (similar) | $5.10 (+10%) | $6.25 (+35%) | $7.40 (+60%) |
Key Differentiators
- Lower minimum supply voltage with full speed (vs ATMEGA164P-20AU)
- Higher Flash density at same pinout (vs ATMEGA324A-AU)
- Lower cost than memory-differentiated variants (vs ATMEGA644A-AU)
Design Notes
Decouple every VCC/AVCC pin pair with a 100 nF ceramic capacitor placed within 5 mm of each pin. Per the Microchip datasheet, AVCC must not differ from VCC by more than 0.3 V, so tie them to the same regulator rail and add a 10 uF bulk capacitor near the package. AREF requires its own 100 nF capacitor; do not leave it floating or ADC accuracy degrades by 2-3 LSB. Enable the internal brown-out detector (BOD) at 2.7 V minimum via fuse settings to prevent Flash corruption during supply droops.
Route the crystal traces between XTAL1/XTAL2 and the crystal with short, symmetric traces and a ground guard ring to minimise stray capacitance. Place the crystal within 10 mm of the MCU pins. For 20 MHz operation, keep digital signal traces away from the analog ADC inputs (ADC0-ADC7) by at least 3 mm or guard them with ground pours to avoid coupling. If using JTAG, route TCK/TMS/TDO/TDI away from PWM outputs to prevent debug glitches from injecting noise into motor drive signals.
Do not exceed 5.5 V on any pin even briefly; the AVR I/O clamps at the ESD diodes and forward-biasing them draws 30+ mA that can latch-up the part. When using ADC channels as digital GPIO (PA0-PA7), disable the digital input buffer by clearing the DIDR0 register to reduce power consumption by 100 uA per channel. The RESET pin must have a 10 kΩ pull-up to VCC; floating reset causes random resets in noisy environments. Estimated: leaving ADC digital inputs enabled at 3.3 V adds 800 uA total quiescent draw at 20 MHz.
Compliance Information
RoHS and REACH compliance per Microchip product page. Not AEC-Q100 qualified; for automotive designs use the ATMEGA164P-20AU equivalent industrial grade or contact Microchip for Q-grade parts. Halogen-free per JEDEC JS7096.