ATMEGA168PA-MU - 8-bit AVR MCU 16KB 20MHz VQFN-32 | Microchip
MPN: ATMEGA168PA-MU β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.85 | $2.85 |
| 10 | $2.56 | $25.60 |
| 100 | $2.21 | $221.00 |
| 500 | $1.95 | $975.00 |
| 1,000 | $1.72 | $1,720.00 |
ATMEGA168PA-MU Overview
An 8-bit AVR microcontroller is a single-chip computer that integrates a RISC CPU core, program flash, SRAM, EEPROM, and peripheral functions such as timers, USART, SPI, and I2C onto one die. Within the power-management hierarchy, MCUs sit at the top of embedded control systems, executing user firmware that sequences peripherals, reads sensors, and drives actuators in everything from consumer appliances to industrial nodes.
Key features include the Advanced RISC architecture with 131 mostly single-cycle instructions and 32 general-purpose working registers, achieving up to 20 MIPS at 20 MHz. The picoPower technology provides multiple sleep modes with sub-uA current draw, critical for battery-powered designs. On-chip peripherals include one 8-bit and one 16-bit timer with PWM, a 10-bit 6-channel ADC, byte-oriented two-wire interface (I2C), SPI, and a serial USART. Brown-out detection, power-on reset, and an internal 8 MHz calibrated RC oscillator reduce external component count.
Technically, the ATmega168PA is fabricated in a low-power process, with the PA suffix denoting the picoPower revision that lowers active and idle current versus the original ATmega168. The Harvard architecture separates program and data buses, enabling single-cycle instruction fetch. In-system programmable flash supports self-programming for firmware updates in the field via bootloader.
Typical applications include battery-powered sensor nodes, Arduino-compatible hobby and prototyping boards, industrial sensor interfaces, and consumer appliance control, where 16 KB of flash and low sleep current align well with cost-sensitive designs.
Design consideration: operate below 8 MHz when running under 2.7V, since the 20 MHz rating requires VCC above 4.5V per the speed-grade curve; plan the BOD threshold to match your supply rail.
This page synthesizes distributor pricing, verified drop-in alternatives, pinout data, and practical design notes not consolidated in the manufacturer datasheet.
Drop-in alternatives for ATMEGA168PA-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 ATMEGA168PA-MU (same form factor and footprint) β differing in Package, Operating Temperature, Timers, Communication Interfaces, ADC Channels.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA328P-MU
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA168A-MU
β Drop-Inβ In Stock
$1.38 / Unit
View Datasheet βATMEGA88PA-MU
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA328-MU
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA168PA-MU Maximum Ratings & Electrical Characteristics
| Core Processor | AVR 8-bit RISC |
| Core Size | 8-bit |
| Speed | 20 MHz |
| Flash Memory | 16 KB (8K x 16) |
| EEPROM | 512 B |
| SRAM | 1 KB |
| Supply Voltage Range | 1.8 V to 5.5 V |
| Number of I/O | 23 |
| ADC Resolution | 10-bit |
| Number of ADC Channels | 6 |
| Peripherals | Brown-out Detect/Reset, POR, PWM, WDT |
| Communication Interfaces | I2C, SPI, USART |
| Timers | Two 8-bit, One 16-bit |
| Operating Temperature | -40C to +85C |
| Package | 32-VQFN (5x5 mm, 0.5 mm pitch, MLF-32) |
| Mounting Type | Surface Mount |
| Data Bus Width | 8 Bit |
| RoHS Status | Compliant (GREEN) |
| Oscillator Type | Internal |
ATMEGA168PA-MU Pin Configuration
| Pin 1 | PD3 β Port D bit 3 / INT1 external interrupt / OC2B PWM output |
| Pin 2 | PD4 β Port D bit 4 / XCK USART external clock / T0 timer input |
| 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 β Port B bit 6 / XTAL1 clock input / TOSC1 timer oscillator |
| Pin 8 | PB7 β Port B bit 7 / XTAL2 clock output / TOSC2 timer oscillator |
| Pin 9 | PD5 β Port D bit 5 / T1 timer input / OC0B PWM output |
| Pin 10 | PD6 β Port D bit 6 / AIN0 analog comparator input / OC0A PWM output |
| Pin 11 | PD7 β Port D bit 7 / AIN1 analog comparator input |
| Pin 12 | PB0 β Port B bit 0 / ICP1 input capture / CLKO clock output |
| Pin 13 | PB1 β Port B bit 1 / OC1A PWM output |
| Pin 14 | PB2 β Port B bit 2 / SS SPI slave select / OC1B PWM output |
| Pin 15 | PB3 β Port B bit 3 / MOSI SPI data output / OC2A PWM output |
| Pin 16 | PB4 β Port B bit 4 / MISO SPI data input |
| Pin 17 | PB5 β Port B bit 5 / SCK SPI serial clock |
| Pin 18 | AVCC β ADC supply voltage |
| Pin 19 | ADC6 β ADC input channel 6 |
| Pin 20 | AREF β ADC analog reference voltage |
| Pin 21 | GND β Ground |
| Pin 22 | ADC7 β ADC input channel 7 |
| Pin 23 | PC0 β Port C bit 0 / ADC0 analog input |
| Pin 24 | PC1 β Port C bit 1 / ADC1 analog input |
| Pin 25 | PC2 β Port C bit 2 / ADC2 analog input |
| Pin 26 | PC3 β Port C bit 3 / ADC3 analog input |
| Pin 27 | PC4 β Port C bit 4 / ADC4 / SDA two-wire data |
| Pin 28 | PC5 β Port C bit 5 / ADC5 / SCL two-wire clock |
| Pin 29 | PC6 β RESET active-low reset input |
| Pin 30 | PD0 β Port D bit 0 / RXD USART receive |
| Pin 31 | PD1 β Port D bit 1 / TXD USART transmit |
| Pin 32 | PD2 β Port D bit 2 / INT0 external interrupt |
Typical Applications
ATMEGA168PA-MU is suitable for 6 applications: Battery-Powered Sensor Nodes, Arduino-Compatible Prototyping Boards, Industrial Sensor Interfaces, Consumer Appliance Control, Motor Control and PWM Drives, IoT Edge Nodes and Remote Monitoring.
Battery-Powered Sensor Nodes
The ATMEGA168PA-MU's picoPower architecture makes it a strong fit for battery-operated wireless and wired sensor nodes. Its power-down sleep mode draws on the order of 0.1 uA while retaining register contents, and power-save mode keeps the asynchronous timer running at under 1 uA for periodic wake-up. A typical node sleeps in power-save, wakes on the watchdog or RTC interval, samples a sensor through the 10-bit ADC, and transmits over USART or SPI before returning to sleep, achieving multi-year life from a coin cell or two AA cells. Because the 16 KB flash is in-system programmable, calibration and reporting logic can be field-updated without swapping parts.
Recommended
Arduino-Compatible Prototyping Boards
The ATmega168 was one of the founding MCUs of the Arduino platform (Arduino Nano, Diecimila), and the ATMEGA168PA-MU remains fully compatible with the Arduino bootloader ecosystem. Its 16 KB flash holds a compact bootloader plus application sketch, the hardware USART at 115200 baud handles sketch upload, and the 10-bit ADC plus PWM timers map directly onto Arduino analogRead and analogWrite APIs. The 32-VQFN 5x5 mm footprint suits compact board designs where DIP packages are too large. For designs needing more headroom, the pin-compatible ATMEGA328P-MU doubles flash and SRAM with zero PCB changes.
Recommended
Industrial Sensor Interfaces
In industrial environments, the ATMEGA168PA-MU interfaces analog sensors to digital control systems. The industrial temperature rating of -40C to +85C covers cabinet and field installations, and the internal 2.56V ADC reference option plus internal 8 MHz oscillator allow fully self-contained analog front ends without precision external components. The 10-bit ADC with up to 6 external channels samples 4-20 mA or ratiometric sensors; SPI and I2C buses connect to external precision ADCs or EEPROMs when higher resolution is needed. Brown-out detection ensures firmware integrity during supply sags caused by motor starts on shared power rails.
Recommended
Consumer Appliance Control
White-goods and small-appliance controls benefit from the ATMEGA168PA-MU's cost structure and integration. A single device replaces discrete logic by combining button matrix scanning on 23 GPIO lines, LED/PWM fan or heater control from the three timers, and temperature sensing via NTC on the 10-bit ADC. The internal oscillator and internal brown-out reset eliminate crystals and supervisor ICs, cutting BOM cost in high-volume builds. The GREEN/RoHS-compliant VQFN-32 package meets global environmental requirements for consumer products, and the in-system programmable flash supports post-assembly firmware correction on the production line.
Recommended
Motor Control and PWM Drives
The ATMEGA168PA-MU drives small DC and stepper motors using its hardware PWM channels: the 16-bit Timer/Counter1 generates high-resolution PWM while the 8-bit timers handle complementary auxiliary outputs. Phase-correct PWM modes reduce acoustic noise in fan and pump applications, and the input-capture unit measures motor speed from hall or encoder pulses with hardware timestamping that does not load the CPU. A 20 MHz clock supports closed-loop control loops in the tens-of-kilohertz range, adequate for small appliance fans, robotics hobby servos, and printer mechanisms. The watchdog timer provides fail-safe shutdown if firmware hangs during stall conditions.
Recommended
IoT Edge Nodes and Remote Monitoring
For cost-sensitive IoT edge nodes, the ATMEGA168PA-MU performs local sensing, filtering, and preprocessing before passing compact data frames to a radio module over SPI or UART. Its 1.8V supply floor allows direct operation from a single lithium cell with a low-dropout regulator, and picoPower sleep modes keep average current within energy-harvesting budgets. The 1 KB SRAM holds state machines and small ring buffers for packetization; designs requiring TLS stacks typically migrate to the pin-compatible ATMEGA328P-MU or pair the ATmega168PA with a dedicated network coprocessor. The VQFN-32 package supports compact two-layer PCBs common in IoT hardware.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA168PA-MU β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA328P-MU | ATMEGA168A-MU | ATMEGA88PA-MU | ATMEGA328-MU |
|---|---|---|---|---|---|
| Package | VQFN-32 (5x5 mm, MLF-32) | VQFN-32 (5x5 mm) - same | VQFN-32 (5x5 mm) - same | VQFN-32 (5x5 mm) - same | VQFN-32 (5x5 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 16 KB | 32 KB | 16 KB | 8 KB | 32 KB |
| SRAM | 1 KB | 2 KB | 1 KB | 1 KB | 2 KB |
| EEPROM | 512 B | 1 KB | 512 B | 512 B | 1 KB |
| Max Clock Speed | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Supply Voltage Range | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 2.7 V to 5.5 V (non-picoPower) | 1.8 V to 5.5 V | 2.7 V to 5.5 V (non-picoPower) |
| picoPower Low Sleep Current | Yes | Yes | No | Yes | No |
| Lifecycle Status | Active | Active | Active | Active | Active |
Key Differentiators
- picoPower technology for ultra-low sleep current (vs ATMEGA168A-MU)
- Cost-optimized memory sizing vs the Uno-class part (vs ATMEGA328P-MU)
- Full memory headroom vs the family entry point (vs ATMEGA88PA-MU)
- Lower sleep current than the non-picoPower 32 KB part (vs ATMEGA328-MU)
Design Notes
Respect the speed-versus-voltage derating curve: 20 MHz operation is guaranteed only at VCC of 4.5V or higher. At 3.3V, keep the clock at or below roughly 13.3 MHz; below 2.7V, limit to about 8 MHz. Running above the curve can cause marginal timing failures that appear only over temperature. For battery designs at 3.3V, either use the internal 8 MHz RC oscillator or select a crystal no higher than 12 MHz, and enable the brown-out detector at 1.8V/2.7V threshold appropriate to your rail.
The 32-VQFN 5x5 mm MLF package has an exposed pad on the underside that must be soldered to a ground pad array on the PCB - it provides the main thermal and ground connection, and skipping it degrades both EMC and ADC accuracy. Use a 3x3 via array under the pad to the ground plane. Place 100 nF decoupling capacitors at each VCC pin (pins 4 and 6) and at AVCC (pin 18), within 2 mm of the pads. AVCC should be connected to VCC through an LC or RC filter when ADC noise matters.
For ADC accuracy, keep analog traces (AREF, AVCC, ADC0-ADC7) away from the SPI/USART digital lines crossing the corner of the package, and add a 100 nF capacitor from AREF (pin 20) to ground close to the pin. If using the two-wire (I2C) interface on PC4/PC5, always fit external pull-up resistors - typically 4.7 kohm at 5V and 2.2-4.7 kohm at 3.3V - since the peripheral only drives the bus open-drain. For ICSP programming access, route MOSI/MISO/SCK/RESET to a standard 2x3 header during layout.
The RESET pin (pin 29) can be disabled in fuses to free a GPIO - avoid this in production unless high-voltage programming recovery is available on your fixture, since a disabled RESET makes ICSP debugging impossible. New parts ship with the internal 8 MHz RC oscillator and 65 ms start-up delay fused by default; a design expecting an external crystal must set the CKOPT/SUT fuse bits at first programming. Also note PC6 doubles as RESET, not a general I/O, despite its port naming.
Compliance Information
Distributor data (FindIC) lists the part as GREEN package, indicating RoHS-compliant lead-free/halogen-free construction. REACH and conflict-minerals status not stated in provided data.
