ATMEGA168-20MI - 8-bit AVR MCU 20MHz 16KB Flash QFN-32 | Microchip
MPN: ATMEGA168-20MI ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.14 | $4.14 |
| 10 | $3.79 | $37.90 |
| 100 | $3.45 | $345.00 |
| 500 | $3.16 | $1,580.00 |
| 1,000 | $2.92 | $2,920.00 |
ATMEGA168-20MI Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a processor core, program memory, data memory, and peripherals such as timers, serial interfaces, and analog-to-digital converters. MCUs sit at the device level of the embedded-systems hierarchy, below system-on-chip and application processors, and above discrete logic. The AVR family from Atmel (now Microchip Technology) popularized the single-cycle RISC execution model for general-purpose embedded control.
Key features of the ATMEGA168-20MI include the Advanced RISC architecture with 131 powerful instructions, most executing in a single clock cycle; 32 general-purpose 8-bit working registers; three flexible timer/counters with compare modes and PWM; and connectivity via I2C (TWI), SPI, and UART/USART. It operates from 1.8 V to 5.5 V with full 20 MHz operation at 4.5 V to 5.5 V, supporting both battery-powered and 5 V industrial designs.
Technically, the device supports self-programming Flash with read-while-write capability, enabling boot-loader-based field updates. DebugWIRE provides on-chip debug over a single wire using the reset line, while In-Circuit Serial Programming (ICSP) permits programming through the SPI port. The picoPower-style sleep modes and a rich clock system (internal 8 MHz RC oscillator, external crystal, watchdog) minimize power in standby-heavy applications.
Typical applications include industrial control panels, sensor nodes and data loggers, consumer appliance control, motor-adjacent logic, and hobbyist/embedded prototypes such as Arduino-compatible boards.
Design consideration: for reliable operation at 20 MHz, use a crystal below 16 MHz if the supply can dip toward 4.5 V, and route the MLF exposed pad to a solid ground pour for thermal and EMC performance.
This page synthesizes verified distributor pricing, drop-in same-package alternatives, pinout data, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA168-20MI — 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 ATMEGA168-20MI (same form factor and footprint) — differing in Package, Timers, Operating Temperature, Supply Voltage Range, RoHS Status.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA168-20MU
✅ Drop-In✓ In Stock
Contact for price
View Datasheet →ATMEGA168-20AU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.82 / Unit
View Datasheet →ATMEGA168A-MU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.38 / Unit
View Datasheet →ATMEGA168PA-MU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.72 / Unit
View Datasheet →ATMEGA328P-MU
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
ATMEGA328-20MU
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
ATMEGA168-20MI Maximum Ratings & Electrical Characteristics
| Core | AVR 8-bit RISC |
| Maximum Clock Frequency | 20 MHz |
| Program Memory Size | 16 KB Flash |
| SRAM Size | 1 KB |
| EEPROM Size | 512 B |
| Supply Voltage Range | 1.8 V to 5.5 V |
| ADC Resolution | 10-bit |
| ADC Channels | 8 |
| Communication Interfaces | I2C, SPI, UART/USART |
| Timers | Three timer/counters with compare modes and PWM |
| I/O Pins | 23 general purpose I/O lines |
| Operating Temperature | -40C to +85C (industrial) |
| Package | 32-pad VQFN / MLF (HVQCCN), square, no-lead |
| Mounting Type | Surface Mount |
| On-Chip Debug | DebugWIRE |
| Programming | ISP (SPI), self-programming Flash with boot loader support |
| RoHS Status | Compliant (GREEN) |
ATMEGA168-20MI Pin Configuration
| Pin 1 | PD3 — Port D bit 3 / digital I/O |
| Pin 2 | PD4 — Port D bit 4 / digital I/O (XCK/T0) |
| Pin 3 | GND — Ground |
| Pin 4 | VCC — Digital supply voltage |
| Pin 5 | GND — Ground |
| Pin 6 | VCC — Digital supply voltage |
| Pin 7 | PB6 — Port B bit 6 / XTAL1 (clock input) |
| Pin 8 | PB7 — Port B bit 7 / XTAL2 (clock output) |
| Pin 9 | PD5 — Port D bit 5 / digital I/O (T1) |
| Pin 10 | PD6 — Port D bit 6 / digital I/O (AIN0) |
| Pin 11 | PD7 — Port D bit 7 / digital I/O (AIN1) |
| Pin 12 | PB0 — Port B bit 0 / digital I/O (ICP1/CLKO) |
| Pin 13 | PB1 — Port B bit 1 / digital I/O (OC1A) |
| Pin 14 | PB2 — Port B bit 2 / digital I/O (SS/OC1B) |
| Pin 15 | PB3 — Port B bit 3 / digital I/O (MOSI/OC2A) |
| Pin 16 | PB4 — Port B bit 4 / digital I/O (MISO) |
| Pin 17 | PB5 — Port B bit 5 / digital I/O (SCK) |
| Pin 18 | AVCC — ADC supply voltage |
| Pin 19 | ADC6 — ADC input channel 6 |
| Pin 20 | AREF — Analog reference voltage |
| Pin 21 | GND — Ground |
| Pin 22 | ADC7 — ADC input channel 7 |
| Pin 23 | PC0 — Port C bit 0 / ADC0 (SCL/PCINT8) |
| Pin 24 | PC1 — Port C bit 1 / ADC1 (SDA/PCINT9) |
| Pin 25 | PC2 — Port C bit 2 / ADC2 (TCK/PCINT10) |
| Pin 26 | PC3 — Port C bit 3 / ADC3 (TMS/PCINT11) |
| Pin 27 | PC4 — Port C bit 4 / ADC4 (TDO/PCINT12) |
| Pin 28 | PC5 — Port C bit 5 / ADC5 (TDI/PCINT13) |
| Pin 29 | PC6 — RESET / PCINT14 (active-low reset) |
| Pin 30 | PD0 — Port D bit 0 / digital I/O (RXD/PCINT16) |
| Pin 31 | PD1 — Port D bit 1 / digital I/O (TXD/PCINT17) |
| Pin 32 | PD2 — Port D bit 2 / digital I/O (INT0/PCINT18) |
Typical Applications
ATMEGA168-20MI is suitable for 6 applications: Industrial Control and Automation Nodes, Sensor Nodes and Data Loggers, Embedded Prototyping and Education Boards, Consumer Appliance Control, Motor-Adjacent Logic and PWM Control, Networking and Communication Accessories.
Industrial Control and Automation Nodes
The ATMEGA168-20MI fits industrial control nodes because it combines a 20 MHz, 20 MIPS AVR core, 16 KB Flash, and the -40C to +85C industrial temperature rating demanded on factory floors. Its 8-channel 10-bit ADC digitizes up to eight sensor inputs such as potentiometers, NTC thermistors, or 4-20 mA conditioned signals, while three timers with PWM drive actuators or heater control. The 1.8 V to 5.5 V supply range tolerates unregulated 5 V industrial rails, and the VFQFN-32 package keeps the controller footprint under 7x7 mm on dense control boards. Placed as the main MCU with a watchdog enabled and brown-out detection fused on, it executes PID loops and Modbus-over-UART routines well within its 1 KB SRAM budget, offering deterministic single-cycle-instruction behavior that 32-bit alternatives often do not need here.
Recommended
Sensor Nodes and Data Loggers
For battery-powered sensor nodes, the ATMEGA168-20MI offers the deep sleep modes (power-down at microamp-level currents) needed for years of operation, plus the 1.8 V floor that allows direct operation from two alkaline cells. The 8-channel 10-bit ADC samples analog sensors without an external converter, and the SPI/UART links stream logged data to SD cards or radios. In a typical topology the MCU wakes on watchdog or pin-change interrupt, reads sensors via I2C, timestamps entries into the 512 B EEPROM, and returns to power-down; with 1-second logging intervals the average current is dominated by the sleep floor. Designers should bias ADC references to the internal 1.1 V bandgap for ratiometric measurements and keep the 20 MHz rating in reserve - running at 1 or 8 MHz (internal RC) at low voltage maximizes efficiency at negligible throughput cost for logging tasks.
Recommended
Embedded Prototyping and Education Boards
The ATMEGA168-20MI is a mainstay of Arduino-class prototype boards because its AVR instruction set, vast community toolchain (avr-gcc, avrdude, Arduino IDE), and DebugWIRE single-wire debug lower the entry barrier dramatically. The 16 KB Flash accommodates beginner-to-intermediate sketches with UART bootloader support built in via self-programming Flash, and the 23 GPIO with PWM and ADC cover LED drivers, buttons, servo signals, and analog readouts without external peripherals. On a breakout board the VFQFN-32 MLF package is hand-reflowable and connects directly to a USB-serial bridge for in-field reprogramming through the bootloader. Since instructions execute in a single cycle, timing-critical bit-banging (WS2812 LEDs, software UART) is predictable, and the same board layout can later accept the pin-compatible ATMEGA328P-MU for sketches that outgrow 16 KB.
Recommended
Consumer Appliance Control
White goods, small appliances, and HVAC controllers benefit from the ATMEGA168-20MI's 5 V-tolerant industrial characterization, rich timer PWM for triac/relay control and fan speed, and I2C/UART links to displays and user interfaces. The 16 KB Flash stores control state machines, EEPROM calibration tables persist across power cycles, and the internal 8 MHz RC oscillator eliminates the cost of a crystal in applications where precise timing is not required - shaving BOM cost in high-volume products. The 10-bit ADC reads NTC temperature sensors and user potentiometers across its eight channels. In a typical appliance board the MCU drives relay coils through transistor drivers, sequences motor starts with PWM ramps, and implements thermal protection with watchdog supervision; the MLF package's exposed ground pad aids thermal dissipation inside enclosed plastic housings.
Recommended
Motor-Adjacent Logic and PWM Control
Although not a dedicated motor driver, the ATMEGA168-20MI excels as the PWM command source and sequencer for small DC and stepper motor systems. Its three timer/counters generate hardware PWM at up to 8-bit resolution on multiple channels, enabling speed and direction control of drivers without CPU overhead, while the 20 MIPS core executes ramp profiles, limit-switch polling, and fault interlocks. The 10-bit ADC reads current-sense amplifiers and back-EMF for basic closed-loop speed regulation within the 1 KB SRAM budget. Typical topology: the MCU PWM outputs feed gate drivers or H-bridge controllers, ADC monitors rail current every PWM cycle, and the UART reports status to a supervisory controller. Running the core at 5 V/20 MHz gives ample interrupt latency headroom for cycle-by-cycle current limiting on brushed motor applications.
Recommended
Networking and Communication Accessories
The ATMEGA168-20MI suits low-speed communication accessory roles such as serial-to-sensor bridges, DMX lighting nodes, and simple fieldbus slaves. The hardware UART/USART runs standard baud rates from the 20 MHz clock, the SPI master clocks peripherals like Ethernet or CAN controllers, and TWI (I2C) manages EEPROMs and RTCs. With 16 KB Flash, compact protocol stacks (e.g., lightweight Modbus RTU slaves) fit comfortably; the 512 B EEPROM stores node addresses and configuration. Because the AVR executes from single-cycle Flash with read-while-write, protocol timeouts remain accurate even while self-programming parameters. Designers should fit the UART to a crystal-derived baud rate (the internal RC is unsuitable for tight-tolerance buses) and use the VFQFN-32 exposed pad as a low-inductance ground for clean signal edges on RS-485 transceiver interfaces.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA168-20MI — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA168-20MU | ATMEGA168PA-MU | ATMEGA328P-MU |
|---|---|---|---|---|
| Package | VFQFN-32 (MLF, HVQCCN) 32-pad | VFQFN-32 - same | VFQFN-32 - same | VFQFN-32 - same |
| Brand | Microchip Technology (Atmel) | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory (Flash) | 16 KB | 16 KB | 16 KB | 32 KB |
| SRAM | 1 KB | 1 KB | 1 KB | 2 KB |
| EEPROM | 512 B | 512 B | 512 B | 1 KB |
| Maximum Clock | 20 MHz (20 MIPS) | 20 MHz | 20 MHz | 20 MHz |
| Supply Voltage | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V |
| Power Technology | Standard AVR | Standard AVR | picoPower (lower sleep current) | picoPower (lower sleep current) |
Key Differentiators
- True drop-in exact match availability (vs ATMEGA168-20MU)
- 20 MHz full-speed operation at low cost (vs ATMEGA168PA-MU)
- Memory headroom via pin-compatible upgrade (vs ATMEGA328P-MU)
Design Notes
The VFQFN-32 (MLF) no-lead package requires the PCB land pattern to include a central thermal/ground pad connected to GND via an array of 3x3 or more vias. This pad is the primary ground return and heat dissipation path; skipping it causes floating-ground behavior and elevated junction temperatures. Follow the Microchip QFN land-pattern application note for stencil aperture design (about 50-70% pad coverage) to avoid excessive solder voiding under the exposed pad.
Decouple VCC/AVCC/GND pad pairs with 100 nF ceramics placed within 2-3 mm of each supply pad, plus a 4.7-10 uF bulk capacitor per rail. AVCC must be connected to VCC even when the ADC is unused (through a low-pass network if ADC noise matters). Program the brown-out detector (BOD) via fuses for 5 V rails to prevent EEPROM corruption during slow brown-outs - this is the single most common field-failure mode of ATmega-based products.
Clock sourcing: at 20 MHz the -20MI speed grade requires VCC in the 4.5-5.5 V range; designs that must operate down to 1.8 V must limit the system clock accordingly or use the internal RC oscillator at 1-8 MHz. Also remember PC6 is RESET by default (fuse-controlled as I/O); leave it asserted high with a 10 k pull-up during programming, and never set the RSTDISBL fuse unless you have a working high-voltage programmer, as it permanently disables ISP.
Compliance Information
Listed as GREEN/RoHS-compliant in Microchip part data for the -MI (industrial) ordering code. AEC-Q100 qualification not claimed for this consumer/industrial-grade part.
