ATMEGA168A-MMHR - 8-Bit AVR MCU 16KB Flash 20MHz | Microchip
MPN: ATMEGA168A-MMHR β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.35 | $2.35 |
| 10 | $2.12 | $21.20 |
| 100 | $1.89 | $189.00 |
| 500 | $1.72 | $860.00 |
| 1,000 | $1.58 | $1,580.00 |
ATMEGA168A-MMHR Overview
An AVR microcontroller is a Harvard-architecture 8-bit RISC device that executes most instructions in a single clock cycle. Within the product hierarchy, the ATmega168A sits under AVR 8-bit MCUs, then microcontrollers (MCU), then embedded processors and integrated circuits. The ATmega168A family is the mid-density member of the classic ATmega48/88/168/328 pin-compatible line, sharing the same 28-pin footprint and peripheral set so firmware can scale between memory densities without PCB changes.
Key features include 16 KB flash with read-while-write, 512 B EEPROM for non-volatile parameter storage, 1 KB SRAM, 23 general-purpose I/O lines, 32 general-purpose working registers, and three flexible timers (two 8-bit, one 16-bit) with PWM. Peripherals include a 10-bit ADC, USART, SPI, and TWI (I2C) interfaces, plus an internal 8 MHz calibrated RC oscillator that removes the need for an external clock in many designs.
The device uses Microchip's low-power AVR core with picoPower technology, supporting multiple sleep modes for battery operation. The 28-VQFN (4x4 mm) package with exposed pad provides a compact footprint for portable and wearable electronics while retaining the full 23 I/O lines of the larger TQFP-32 variant.
Typical applications include Arduino-compatible development boards, battery-powered sensor nodes, motor control, and industrial automation front-ends. The 1.8 V to 5.5 V range allows direct operation from single-cell Li-Ion or 3.3 V/5 V rails.
When designing, decouple VCC and AVCC with 100 nF ceramic capacitors placed close to the pins, and connect the exposed pad to ground for thermal and noise performance. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA168A-MMHR 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-MMHR (same form factor and footprint) β differing in ADC, Instruction Set, Package.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA168A-MMH
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA88A-MMHR
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA48A-MMHR
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA328P-MMHR
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA168PA-MMHR
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA168A-MMHR Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Program Memory | 16 KB Flash (8K x 16) |
| EEPROM | 512 B |
| SRAM | 1 KB |
| Maximum Clock Frequency | 20 MHz |
| Operating Voltage | 1.8 V to 5.5 V |
| Throughput | Up to 20 MIPS at 20 MHz |
| General Purpose I/O | 23 lines |
| General Purpose Registers | 32 (8-bit) |
| Timers | Two 8-bit, one 16-bit with PWM |
| ADC | 10-bit successive approximation |
| Communication Interfaces | USART, SPI, TWI (I2C) |
| Internal Oscillator | 8 MHz calibrated RC |
| Package | 28-VQFN (4x4 mm) with exposed pad |
| Mounting Type | Surface Mount |
| Operating Temperature | -40 C to +85 C |
| Instruction Set | 133 powerful instructions, most single-cycle |
| RoHS Status | Compliant |
ATMEGA168A-MMHR Pin Configuration
| Pin 1 | PD3 β Port D, bit 3 / INT1 / OC2B |
| Pin 2 | PD4 β Port D, bit 4 / T0 / XCK |
| 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 / TOSC1 |
| Pin 8 | PB7 β Port B, bit 7 / XTAL2 / TOSC2 |
| Pin 9 | PD5 β Port D, bit 5 / T1 / OC0B |
| Pin 10 | PD6 β Port D, bit 6 / AIN0 / OC0A |
| Pin 11 | PD7 β Port D, bit 7 / AIN1 |
| Pin 12 | PB0 β Port B, bit 0 / ICP1 / CLKO |
| Pin 13 | PB1 β Port B, bit 1 / OC1A |
| Pin 14 | PB2 β Port B, bit 2 / SS / OC1B |
| Pin 15 | PB3 β Port B, bit 3 / MOSI / OC2A |
| Pin 16 | PB4 β Port B, bit 4 / MISO |
| Pin 17 | PB5 β Port B, bit 5 / SCK |
| Pin 18 | AVCC β Analog supply voltage |
| Pin 19 | ADC6 β Analog input channel 6 |
| Pin 20 | AREF β Analog reference voltage |
| Pin 21 | GND β Ground |
| Pin 22 | ADC7 β Analog input channel 7 |
| Pin 23 | PC0 β Port C, bit 0 / ADC0 |
| Pin 24 | PC1 β Port C, bit 1 / ADC1 |
| Pin 25 | PC2 β Port C, bit 2 / ADC2 |
| Pin 26 | PC3 β Port C, bit 3 / ADC3 |
| Pin 27 | PC4 β Port C, bit 4 / ADC4 / SDA |
| Pin 28 | PC5 β Port C, bit 5 / ADC5 / SCL |
Typical Applications
ATMEGA168A-MMHR is suitable for 6 applications: Arduino-Compatible Development Boards, Battery-Powered Sensor Nodes, Motor Control and Robotics, Industrial Automation Front-Ends, Consumer Electronics Control, Embedded Data Logging.
Arduino-Compatible Development Boards
The ATMEGA168A-MMHR fits Arduino-compatible development boards because it is the same 8-bit AVR core used on classic Arduino hardware, with 16 KB flash and 1 KB SRAM sufficient for the bootloader plus typical sketches. The 28-pin VQFN (4x4 mm) package provides 23 I/O lines, enough for digital and analog headers, while the internal 8 MHz RC oscillator allows operation without an external crystal in cost-reduced variants. The MiniCore Arduino hardware package explicitly supports the ATmega168 family, so toolchain support is mature. A trade-off is that the VQFN package requires reflow soldering and is harder to hand-prototype than the TQFP-32 ATMEGA168A-AU, so it suits production boards rather than breadboard builds.
Recommended
Battery-Powered Sensor Nodes
The ATMEGA168A-MMHR suits battery-powered sensor nodes because it operates from 1.8 V to 5.5 V, allowing direct connection to a single-cell Li-Ion battery without a boost converter, and its AVR core supports multiple sleep modes for low average current. The 10-bit ADC samples analog sensors such as thermistors or photodiodes, while the TWI (I2C) interface connects digital sensors and the USART handles wireless module communication. With 16 KB flash and 1 KB SRAM, the device can run sensor fusion and radio stack firmware without external memory. The main trade-off is that at 1.8 V the maximum clock is reduced, so designers must balance throughput against battery life when selecting the operating point.
Recommended
Motor Control and Robotics
The ATMEGA168A-MMHR is used in motor control and robotics because its three timers, including a 16-bit timer with PWM, generate the precise pulse-width modulation signals required for H-bridge and servo control. The 23 general-purpose I/O lines drive direction pins, limit switches, and encoder inputs, while the 10-bit ADC reads current-sense shunts for overcurrent detection. At 20 MHz the core delivers up to 20 MIPS, enough for a simple PID loop running alongside communication tasks. The 1.8 V to 5.5 V range allows direct interfacing with 5 V motor drivers or 3.3 V logic. A design consideration is that PWM jitter must be minimized by using hardware timers rather than software loops, especially when driving multiple motors.
Recommended
Industrial Automation Front-Ends
The ATMEGA168A-MMHR serves industrial automation front-ends where a compact microcontroller handles sensor polling, relay sequencing, and serial communication. The 28-pin VQFN (4x4 mm) package saves board area on dense I/O modules, while the -40 C to +85 C operating range covers most factory environments. USART, SPI, and TWI interfaces connect to industrial sensors, display drivers, and host controllers, and the 512 B EEPROM stores calibration constants without external memory. The 5.5 V maximum supply allows direct operation from a regulated 5 V backplane rail. A trade-off is that the device is not AEC-Q100 qualified, so it is unsuitable for automotive under-hood applications; for those, an automotive-grade MCU should be selected instead.
Recommended
Consumer Electronics Control
The ATMEGA168A-MMHR is used in consumer electronics control because it provides a complete 8-bit MCU with 16 KB flash, 23 I/O lines, and integrated USART, SPI, and TWI in a 4x4 mm package that fits small enclosures. It can manage button matrices, LED indicators, and capacitive touch sensing while communicating with a main processor over I2C or UART. The internal 8 MHz RC oscillator reduces bill-of-materials cost by eliminating the external crystal in non-timing-critical designs. The 1.8 V to 5.5 V range supports both 3.3 V and 5 V system rails. A design consideration is that the internal oscillator has limited accuracy over temperature, so an external crystal should be added when precise UART baud rates or real-time clocks are required.
Recommended
Embedded Data Logging
The ATMEGA168A-MMHR supports embedded data logging because its 512 B EEPROM stores configuration and calibration data across power cycles, while the 16 KB flash holds logging firmware and the 1 KB SRAM buffers samples before writing to external memory. The 10-bit ADC digitizes analog inputs, and the SPI interface connects SD cards or serial flash for bulk storage. The 1.8 V to 5.5 V range allows the logger to run from a 3.3 V rail or directly from a Li-Ion cell. At 20 MHz the core can timestamp and compress samples in real time. A trade-off is that 1 KB SRAM limits in-RAM buffering, so designs with high sample rates should stream data to external memory rather than buffering large blocks internally.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA168A-MMHR β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA168A-MMH | ATMEGA88A-MMHR | ATMEGA48A-MMHR | ATMEGA328P-MMHR | ATMEGA168PA-MMHR |
|---|---|---|---|---|---|---|
| Package | 28-VQFN (4x4 mm) | 28-VQFN (4x4 mm) - same | 28-VQFN (4x4 mm) - same | 28-VQFN (4x4 mm) - same | 28-VQFN (4x4 mm) - same | 28-VQFN (4x4 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 16 KB | 16 KB | 8 KB | 4 KB | 32 KB | 16 KB |
| SRAM | 1 KB | 1 KB | 512 B | 512 B | 2 KB | 1 KB |
| EEPROM | 512 B | 512 B | 512 B | 256 B | 1 KB | 512 B |
| Maximum Clock | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Operating 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 | 1.8 V to 5.5 V | 1.8 V to 5.5 V |
| General Purpose I/O | 23 lines | 23 lines | 23 lines | 23 lines | 23 lines | 23 lines |
| Packaging | Tape & Reel | Tray | Tape & Reel | Tape & Reel | Tape & Reel | Tape & Reel |
| picoPower Technology | No | No | No | No | Yes | Yes |
Key Differentiators
- Mid-density flash in the pin-compatible ATmega family (vs ATMEGA88A-MMHR)
- Lower cost than the 32 KB variant (vs ATMEGA328P-MMHR)
- Standard AVR core without picoPower premium (vs ATMEGA168PA-MMHR)
- Tape-and-reel packaging for automated assembly (vs ATMEGA168A-MMH)
Design Notes
Decouple both VCC pins (pins 4 and 6) and the AVCC pin (pin 18) with 100 nF ceramic capacitors placed within a few millimeters of the package. Add a 10 uF bulk capacitor on the board rail. For ADC accuracy, insert a 10 uH inductor or ferrite bead between VCC and AVCC to isolate digital switching noise from the analog supply, and tie AREF to AVCC through a 100 nF capacitor when using the internal reference.
The 28-VQFN (4x4 mm) package has an exposed thermal pad that must be soldered to a grounded copper area for mechanical strength and heat spreading. Use a stencil aperture of approximately 50-80% of the pad area to control solder volume and avoid bridging. Route the crystal (if used) on pins 7 and 8 with short, symmetric traces and guard them with ground; keep switching signals such as PWM outputs away from the XTAL pins to prevent clock jitter.
Do not leave the RESET pin floating; although an internal pull-up exists, add an external 10 kOhm pull-up and a 100 nF capacitor to ground for reliable operation in noisy environments. When migrating firmware between ATmega48A/88A/168A/328P variants, update the device signature and fuse bytes in the programmer, because the signature differs even though the pinout is identical. Estimated: at 5 V and 20 MHz the core draws roughly 10-12 mA, so verify the regulator can supply the MCU plus peripherals before finalizing the power budget.
Compliance Information
RoHS compliance and lead-free status are stated on the Microchip ATmega168A product page and distributor listings. The device is not AEC-Q100 qualified, so it is not intended for automotive applications. REACH, halogen-free, and conflict-minerals status were not confirmed in the retrieved data.
