ATMEGA168A-MU - 8-bit AVR MCU 16KB Flash 20MHz VQFN-32 | Microchip
MPN: ATMEGA168A-MU β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.42 | $2.42 |
| 10 | $2.18 | $21.80 |
| 100 | $1.86 | $186.00 |
| 500 | $1.62 | $810.00 |
| 1,000 | $1.38 | $1,380.00 |
ATMEGA168A-MU Overview
An 8-bit microcontroller (MCU) is a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Within the power-management and embedded-control hierarchy, the ATmega168A belongs to the AVR family of reduced-instruction-set (RISC) controllers, positioned as the mid-memory variant of the ATmega48/88/168/328 product ladder. Such MCUs execute control, sensing, and communication tasks in embedded systems ranging from consumer appliances to industrial nodes.
Key features include 133 powerful instructions with most executed in a single clock cycle, delivering up to 20 MIPS throughput at 20 MHz. The device offers 23 general-purpose I/O lines, 32 general-purpose working registers, three flexible timer/counters with compare modes, and both internal and external interrupt sources. Serial connectivity is comprehensive: a byte-oriented 2-wire interface (I2C/TWI), a programmable USART, and an SPI serial port. On-chip analog resources include a 6-channel 10-bit ADC in the QFN package variant.
The AVR enhanced RISC architecture combines a rich instruction set with 32 general-purpose working registers directly connected to the arithmetic logic unit, allowing every register access to complete in one cycle. In-system programmable flash with read-while-write support permits firmware updates on the assembled board through SPI, and the picoPower-compatible low-power modes (idle, power-down, power-save) reduce consumption for battery designs.
Typical applications include sensor acquisition nodes using the 10-bit ADC, motor and LED control via the timer PWM channels, and serial communication bridges using USART, SPI, or TWI. It is also a common choice for Arduino-compatible board designs and hobby-to-industrial migration paths.
When designing with the ATMEGA168A-MU, ensure decoupling capacitors sit close to the multiple VCC/AVCC pins of the exposed-pad VQFN-32, and connect the exposed pad to ground for thermal and noise performance.
This page synthesizes distributor availability data, drop-in alternatives, pinout detail, and practical design notes not consolidated in the manufacturer datasheet.
Drop-in alternatives for ATMEGA168A-MU 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 ATMEGA168A-MU (same form factor and footprint) β differing in Package, Operating Temperature, Timers, Communication Interfaces, Program Memory Size.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA168PA-MU
β Drop-Inβ In Stock
$1.72 / Unit
View Datasheet βATMEGA168A-MMHR
β Drop-Inβ In Stock
$1.58 / Unit
View Datasheet βATMEGA168-20MU
β Drop-Inβ In Stock
Contact for price
View Datasheet βATMEGA88A-MU
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA48A-MU
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA328P-MU
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA168A-MU Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Flash Memory | 16 KB (8K x 16) ISP |
| EEPROM | 512 B |
| SRAM | 1 KB |
| Maximum Clock Frequency | 20 MHz |
| Maximum Throughput | 20 MIPS at 20 MHz |
| Supply Voltage Range | 2.7 V to 5.5 V |
| General Purpose I/O Lines | 23 |
| Working Registers | 32 x 8-bit general purpose |
| Timer/Counters | 3 flexible with compare modes |
| ADC | 10-bit, 6-channel (QFN package) |
| Serial Interfaces | USART, SPI, 2-wire (I2C/TWI) |
| Package | 32-VQFN (5x5 mm) exposed pad |
| Mounting Type | Surface Mount |
| Lifecycle Status | Active |
| Data Bus Width | 8 bit |
| Instruction Set | 133 instructions, mostly single-cycle |
ATMEGA168A-MU Pin Configuration
| Pin 1 | PD3 (PCINT19/OC2B/INT1) β Port D, pin-change interrupt / Timer2 output compare B / external interrupt 1 |
| Pin 2 | PD4 (PCINT20/XCK/T0) β Port D, USART external clock / Timer0 external clock |
| Pin 3 | GND β Ground |
| Pin 4 | VCC β Digital supply voltage |
| Pin 5 | GND β Ground |
| Pin 6 | VCC β Digital supply voltage |
| Pin 7 | PB6 (PCINT6/XTAL1/TOSC1) β Crystal oscillator input / Timer oscillator |
| Pin 8 | PB7 (PCINT7/XTAL2/TOSC2) β Crystal oscillator output |
| Pin 9 | PD5 (PCINT21/OC0B/T1) β Port D, Timer0 output compare B / Timer1 external clock |
| Pin 10 | PD6 (PCINT22/OC0A/AIN0) β Port D, Timer0 output compare A / analog comparator positive input |
| Pin 11 | PD7 (PCINT23/AIN1) β Port D, analog comparator negative input |
| Pin 12 | PB0 (PCINT0/CLKO/ICP1) β Port B, clock output / Timer1 input capture |
| Pin 13 | PB1 (PCINT1/OC1A) β Port B, Timer1 output compare A |
| Pin 14 | PB2 (PCINT2/SS/OC1B) β Port B, SPI slave select / Timer1 output compare B |
| Pin 15 | PB3 (PCINT3/MOSI/OC2A) β Port B, SPI master output / Timer2 output compare A |
| Pin 16 | PB4 (PCINT4/MISO) β Port B, SPI master input |
| Pin 17 | PB5 (PCINT5/SCK) β Port B, SPI serial clock |
| Pin 18 | AVCC β ADC supply voltage |
| Pin 19 | ADC6 β ADC input channel 6 |
| Pin 20 | AREF β Analog reference voltage |
| Pin 21 | GND β Ground |
| Pin 22 | ADC7 β ADC input channel 7 |
| Pin 23 | PC0 (PCINT8/ADC8) β Port C, ADC channel 8 |
| Pin 24 | PC1 (PCINT9/ADC9) β Port C, ADC channel 9 |
| Pin 25 | PC2 (PCINT10/ADC10) β Port C, ADC channel 10 |
| Pin 26 | PC3 (PCINT11/ADC11) β Port C, ADC channel 11 |
| Pin 27 | PC4 (PCINT12/SDA/ADC12) β Port C, TWI data / ADC channel 12 |
| Pin 28 | PC5 (PCINT13/SCL/ADC13) β Port C, TWI clock / ADC channel 13 |
| Pin 29 | PC6 (PCINT14/RESET) β Reset input / port pin |
| Pin 30 | PD0 (PCINT16/RXD) β Port D, USART receive |
| Pin 31 | PD1 (PCINT17/TXD) β Port D, USART transmit |
| Pin 32 | PD2 (PCINT18/INT0) β Port D, external interrupt 0 |
Typical Applications
ATMEGA168A-MU is suitable for 6 applications: Sensor Acquisition Nodes, Motor and LED Control, Industrial Communication Bridges, Consumer Appliance Control, Arduino-Compatible Prototyping, IoT End Nodes and Remote Monitoring.
Sensor Acquisition Nodes
The ATMEGA168A-MU fits battery-powered and wired sensor nodes because its integrated 10-bit ADC offers up to 6 channels in the QFN package, eliminating an external converter for thermistor, potentiometer, or analog accelerometer interfaces. The 20 MIPS throughput at 20 MHz handles oversampling and digital filtering while the 1 KB SRAM buffers sample windows. Placed in power-down sleep between conversions, the AVR wakes on external interrupt or watchdog timeout, keeping average current in the microampere-to-milliampere range depending on duty cycle. The VQFN-32 5x5 mm footprint supports compact PCB sensor modules, and the TWI bus can chain digital sensors such as the AT30TS750 temperature sensor alongside the analog inputs.
Recommended
Motor and LED Control
Three flexible timer/counters with compare modes make the ATMEGA168A-MU well suited to PWM generation for DC motor speed control and LED dimming. The 16-bit Timer/Counter1 provides high-resolution PWM while two 8-bit timers handle auxiliary channels or tick scheduling. With 23 GPIO lines, the MCU can drive a gate-driver front end such as the MIC4102 half-bridge driver for brushed or stepper motors. Because PWM generation is hardware-based, CPU load remains low for supervisory tasks like current-limit protection through the ADC. At 20 MHz, PWM carrier frequencies well above audible range are achievable, avoiding LED flicker and motor whine in consumer products.
Recommended
Industrial Communication Bridges
The ATMEGA168A-MU integrates a hardware USART, SPI, and byte-oriented 2-wire (I2C/TWI) interface, allowing protocol conversion between legacy serial devices and modern buses. A typical bridge design places the MCU between an RS-485 transceiver such as the ATA6561 on the USART side and SPI peripherals on the other, forwarding Modbus-RTU frames with CRC computed in firmware within the 20 MIPS budget. The 512 B EEPROM stores node addresses and configuration persistently, and the 16 KB flash holds protocol stacks comfortably. Hardware SPI supports multi-slave arbitration with chip-select GPIOs, and the read-while-write flash allows field firmware updates without removing the device from the industrial network.
Recommended
Consumer Appliance Control
In appliances such as coffee makers, fans, and small HVAC controls, the ATMEGA168A-MU provides the right balance of cost, memory, and integration. The 2.7 V to 5.5 V supply range accepts mains-derived linear supplies without a dedicated regulator IC in many designs. Timer PWM drives triac or relay timing, touch-button decoding uses ADC channels or pin-change interrupts, and the USART supports service diagnostics. The 5x5 mm VQFN-32 package suits dense main-PCB layouts where DIP MCUs would not fit. Firmware for temperature profiles and user-interface state machines fits easily in 16 KB, and the 32 general-purpose registers simplify interrupt-driven UI code with low register-bank switching overhead.
Recommended
Arduino-Compatible Prototyping
The ATMEGA168A-MU is the 16 KB sibling of the ATmega328P used on the Arduino Uno and is fully supported by the Arduino IDE via the ATmega168 board definition. Designers building custom Arduino-compatible boards use the same 16 MHz crystal, ISP header, and FTDI/USB-serial front end; a bootloader such as Optiboot fits within the 16 KB flash when trimmed. The 10-bit ADC maps directly to analogRead(), and hardware SPI/TWI support the Wire and SPI libraries unchanged. For prototypes expected to grow past 16 KB, designing the footprint to accept the pin-compatible ATMEGA328P-MU preserves layout investment while doubling program space at production time.
Recommended
IoT End Nodes and Remote Monitoring
For sub-GHz and LPWAN IoT nodes, the ATMEGA168A-MU acts as the application controller driving a radio module over SPI or UART. Its sleep modes are critical: in power-down between reporting intervals, current consumption drops to the microampere range, enabling multi-year battery life when paired with a sensor and a low-power radio such as the ATA578x receiver family. The 512 B EEPROM stores device IDs and calibration constants, and the ADC reads battery voltage via divider for health telemetry. Wake-up via watchdog or external interrupt from a motion sensor keeps the design event-driven. The compact VQFN-32 package allows the controller to share a small PCB with the RF section.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA168A-MU β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA168PA-MU | ATMEGA88A-MU | ATMEGA48A-MU | ATMEGA328P-MU |
|---|---|---|---|---|---|
| Package | 32-VQFN (5x5 mm) | 32-VQFN (5x5 mm) - same | 32-VQFN (5x5 mm) - same | 32-VQFN (5x5 mm) - same | 32-VQFN (5x5 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 16 KB | 16 KB | 8 KB | 4 KB | 32 KB |
| SRAM | 1 KB | 1 KB | 1 KB | 512 B | 2 KB |
| EEPROM | 512 B | 512 B | 512 B | 256 B | 1 KB |
| Maximum Clock | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Supply Voltage | 2.7 V to 5.5 V | 1.8 V to 5.5 V (PA speed grades) | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 1.8 V to 5.5 V (P speed grades) |
| Low Power Technology | Standard AVR sleep modes | picoPower | Standard AVR sleep modes | Standard AVR sleep modes | picoPower |
| Drop-in Compatible with ATMEGA168A-MU | - | Yes - pin-to-pin | Yes - pin-to-pin (less flash) | Yes - pin-to-pin (less flash) | Yes - pin-to-pin (more flash) |
Key Differentiators
- Balanced 16 KB flash tier in the AVR memory ladder (vs ATMEGA88A-MU)
- Lowest-cost option for large memory needs (vs ATMEGA328P-MU)
- Honest trade-off: no picoPower technology (vs ATMEGA168PA-MU)
- More SRAM than the smallest family member (vs ATMEGA48A-MU)
Design Notes
The ATMEGA168A-MU VQFN-32 has two VCC pins (4, 6), AVCC (18), and multiple ground pins (3, 5, 21) plus an exposed thermal pad. Connect every VCC and AVCC pin to the 5 V or 3.3 V rail with a 100 nF ceramic capacitor placed within 2 mm of each pin, and tie AVCC to VCC through an LC filter (10 uH + 100 nF) when ADC accuracy matters. Solder the exposed pad to a grounded copper pour; it improves heat dissipation and reduces ground bounce for the ADC and comparator.
At 5 V and 20 MHz, active-mode current is in the several-milliampere range per the datasheet electrical characteristics; in power-down sleep it falls to the microampere range. Estimated: a node sleeping 99% of the time at 1 uA and active 1% at 5 mA draws an average of roughly 51 uA, which a 500 mAh CR2032 supports for well over a year. If battery life is the binding constraint, use the pin-compatible picoPower ATMEGA168PA-MU which lowers sleep current further without layout changes.
Fuse misconfiguration is the most common field failure with AVR devices: selecting external clock when only a crystal is fitted, or disabling SPI when ISP programming is needed, can lock the part. Always verify fuse settings (low/high/extended byte) against the family datasheet before flashing, and keep the reset pin (PC6) decoupled with a 100 nF capacitor with a 10 kohm pull-up for reliable brown-out behavior. Enable the internal brown-out detector for mains-powered designs to prevent EEPROM corruption during power glitches.
For ADC measurements, keep analog traces (AREF, ADC channels) short and away from crystal and PWM switching lines. Use the ADC noise reduction sleep mode during conversions: it halts the CPU and I/O clocks, measurably reducing quantization noise. A 100 nF capacitor directly on AREF with the internal reference selected gives the most repeatable results; avoid driving AREF externally while the internal reference is enabled, as this can damage the reference amplifier per the datasheet.
Compliance Information
Compliance status not stated in the provided verified web data; consult the Microchip product page and product environmental data for RoHS/REACH details.
