ATMEGA48-20MI - 8-bit AVR MCU 20MHz 4KB Flash VQFN-32 | Microchip
MPN: ATMEGA48-20MI ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0 | $0.00 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
ATMEGA48-20MI Overview
An 8-bit AVR microcontroller is a single-chip processor that executes an advanced RISC instruction set (131 instructions, most in a single clock cycle) and integrates program Flash, data SRAM, EEPROM, timers, analog peripherals and I/O on one die. Within the power-management hierarchy, MCUs like the ATmega48 sit at the node level, reading sensors and driving actuators in embedded systems ranging from consumer appliances to industrial control.
Key features include 23 general-purpose I/O lines, three flexible timer/counters with compare modes, an 8-channel 10-bit ADC, and debugWIRE on-chip debugging that uses only the reset line. The picoPower technology supports multiple sleep modes for battery-operated designs, and operation spans 1.8 V to 5.5 V at full 20 MHz speed grade.
Architecturally, the AVR uses a Harvard structure with 32 general-purpose working registers directly connected to the ALU, allowing two independent instructions to execute in one cycle. Self-programming Flash enables in-system programming (ISP) and bootloader firmware updates in the field, while the 32-pin QFN footprint with exposed pad improves thermal and ground performance on compact two-layer PCBs.
Typical applications include sensor nodes and battery-powered IoT devices (leveraging low-voltage 1.8 V operation and sleep modes), small motor and LED control boards using the three timers, and industrial consumer appliances where debugWIRE simplifies in-circuit development without a JTAG pod.
When designing, remember the industrial temperature range (-40 C to +85 C) applies to the MI suffix, and Brown-out detection plus the internal 8 MHz RC oscillator eliminate external components at moderate clock rates; reserve the crystal option for UART-heavy or timing-critical designs.
This page synthesizes distributor stock data, drop-in same-family alternatives, pinout detail, and practical design notes not consolidated in the manufacturer datasheet, with pricing freshness noted as of 2026-09-18.
Drop-in alternatives for ATMEGA48-20MI — 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 ATMEGA48-20MI (same form factor and footprint) — differing in Operating Temperature, Package, ADC Channels, Timers, Supply Voltage Range.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA48-20MU
✅ Drop-In📋 Reference alternative (not in catalog)
ATMEGA48A-MU
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
ATMEGA48PA-MU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.08 / Unit
View Datasheet →ATMEGA88-20MU
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
ATMEGA168-20MU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
Contact for price
View Datasheet →ATMEGA328P-MU
✅ Drop-In✓ In Stock
$1.28 / Unit
View Datasheet →ATMEGA48V-10MU
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.38 / Unit
View Datasheet →ATMEGA48-20MI Maximum Ratings & Electrical Characteristics
| Core | AVR 8-bit RISC |
| Core Size | 8-bit |
| Max Clock Frequency | 20 MHz |
| Throughput | Up to 20 MIPS at 20 MHz |
| Flash Memory | 4 KB (2K x 16) In-System Programmable |
| SRAM | 512 B |
| EEPROM | 256 B |
| Operating Voltage Range | 1.8 V to 5.5 V |
| I/O Count | 23 general purpose I/O lines |
| Timers | 3 timer/counters with compare modes |
| ADC | 8-channel 10-bit |
| On-Chip Debug | debugWIRE |
| Working Registers | 32 x 8-bit general purpose |
| Instruction Set | 131 instructions, mostly single-cycle |
| Operating Temperature | -40 C to +85 C (industrial) |
| Package | 32-VQFN (5x5 mm) exposed pad |
| Mounting Type | Surface Mount |
| Technology | picoPower low power |
| Series | AVR ATmega |
ATMEGA48-20MI Pin Configuration
| Pin 1 | PD3 — Port D, bit 3 (GPIO / INT1) |
| Pin 2 | PD4 — Port D, bit 4 (GPIO / 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/TOSC1) |
| Pin 8 | PB7 — Port B, bit 7 (XTAL2/TOSC2) |
| Pin 9 | PD5 — Port D, bit 5 (GPIO / T1) |
| Pin 10 | PD6 — Port D, bit 6 (GPIO / AIN0) |
| Pin 11 | PD7 — Port D, bit 7 (GPIO / AIN1) |
| Pin 12 | PB0 — Port B, bit 0 (GPIO / ICP1/OC0A) |
| Pin 13 | PB1 — Port B, bit 1 (GPIO / OC1A) |
| Pin 14 | PB2 — Port B, bit 2 (GPIO / SS/OC1B) |
| Pin 15 | PB3 — Port B, bit 3 (GPIO / MOSI/OC2A) |
| Pin 16 | PB4 — Port B, bit 4 (GPIO / MISO) |
| Pin 17 | PB5 — Port B, bit 5 (GPIO / 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 (GPIO / ADC0) |
| Pin 24 | PC1 — Port C, bit 1 (GPIO / ADC1) |
| Pin 25 | PC2 — Port C, bit 2 (GPIO / ADC2) |
| Pin 26 | PC3 — Port C, bit 3 (GPIO / ADC3) |
| Pin 27 | PC4 — Port C, bit 4 (GPIO / ADC4/SDA) |
| Pin 28 | PC5 — Port C, bit 5 (GPIO / ADC5/SCL) |
| Pin 29 | PC6 — Port C, bit 6 (RESET / debugWIRE) |
| Pin 30 | PD0 — Port D, bit 0 (GPIO / RXD) |
| Pin 31 | PD1 — Port D, bit 1 (GPIO / TXD) |
| Pin 32 | PD2 — Port D, bit 2 (GPIO / INT0) |
Typical Applications
ATMEGA48-20MI is suitable for 6 applications: Battery-Powered Sensor Nodes, Small Motor and Fan Control, LED Lighting and Dimming Control, Consumer Appliance Control Panels, Industrial Sensing and 4-20 mA Transmitters, Hobby, Education and Rapid Prototyping.
Battery-Powered Sensor Nodes
The ATMEGA48-20MI suits battery-powered sensor nodes because its picoPower technology provides multiple sleep modes and it operates from 1.8 V, allowing direct use of a two-cell alkaline supply without a boost converter. A typical node places the MCU in power-down between measurement intervals, waking on pin-change or watchdog interrupt to read a thermistor via the 8-channel 10-bit ADC and transmit over a simple UART or RF link. Using the internal 8 MHz RC oscillator eliminates the crystal and its associated quiescent load, reducing component count on cost-optimized nodes. The 4 KB Flash is generally sufficient for protocol-and-measure firmware; if OTA update payloads grow, the pin-compatible ATMEGA328P-MU allows a memory upgrade without PCB change.
Recommended
Small Motor and Fan Control
Three flexible timer/counters with compare and PWM modes make the ATMEGA48-20MI an economical controller for small DC or brushless fan/motor boards. One timer generates the PWM carrier (e.g., 20 kHz to stay above audible range) while a second counts encoder or tacho pulses for closed-loop speed regulation, and the 10-bit ADC samples a back-EMF or current-sense voltage for stall detection. Running from a 5 V rail at 20 MHz provides ample MIPS for a PI loop at kHz rates. The 32-VQFN exposed-pad package provides a solid ground reference for switching noise; decouple AVCC separately and keep the motor-driver gate traces away from the ADC reference to preserve conversion accuracy.
Recommended
LED Lighting and Dimming Control
In LED luminaires and dimmable fixtures, the ATMEGA48-20MI generates hardware PWM on multiple channels simultaneously using its three timers, supporting color mixing or multi-zone dimming without CPU-intensive software timing. The 10-bit ADC can read a potentiometer, 0-10 V analog dimming input, or NTC temperature sensor mounted on the LED heatsink, enabling thermal foldback that extends LED lifetime. Operation from 1.8 V to 5.5 V allows direct integration with low-voltage control rails. Because hardware PWM continues during CPU sleep, the firmware can park in idle mode between dimming-level changes, trimming standby consumption; the 4 KB Flash accommodates typical dimming-curve and communication firmware with room to spare.
Recommended
Consumer Appliance Control Panels
Washing machines, small HVAC controllers, and kitchen appliances commonly use ATmega-class MCUs for keypad scanning, display driving, and relay control. The ATMEGA48-20MI's 23 GPIO lines cover a 4x4 keypad plus segment or LED-matrix display in one package, and its industrial temperature rating (-40 C to +85 C) covers unventilated appliance enclosures. debugWIRE on-chip debugging through the RESET line lets developers instrument code on the actual production board without sacrificing I/O for a debug header. The 256 B EEPROM stores cycle counters and user presets across power cycles. Brown-out detection ensures predictable reset behavior during mains dips, a frequent occurrence in appliance environments.
Recommended
Industrial Sensing and 4-20 mA Transmitters
The ATMEGA48-20MI's 10-bit ADC with selectable internal bandgap reference makes it viable for industrial loop-powered transmitters, where it digitizes a sensor (RTD, strain bridge, or pressure element) and drives a PWM-filtered or DAC-based 4-20 mA output stage. Running from a 3.3 V or 5 V loop-derived supply within its 1.8-5.5 V range simplifies power extraction from the current loop. The industrial -40 C to +85 C rating matches field-mounted transmitter enclosures. Because loop budget is limited, choose the ATMEGA48PA variant for lower active current, and place the ADC in noise-reduction mode during conversions to lower sample noise on millivolt-level bridge signals.
Recommended
Hobby, Education and Rapid Prototyping
The ATmega48 family is fully supported by open toolchains (avr-gcc, Microchip Studio, and the MiniCore Arduino hardware package), making the ATMEGA48-20MI a favorite for prototypes, student projects, and maker products. Its 4 KB Flash and 512 B SRAM force disciplined C code, which is an excellent teaching constraint, while debugWIRE single-wire debugging works with low-cost programmers. When a prototype outgrows the memory, moving to the pin-compatible ATMEGA88, ATMEGA168, or ATMEGA328P on the same QFN-32 footprint requires no layout change - a property unique to this AVR family ladder. Distributor stock and same-day shipping keep prototype iterations fast.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA48-20MI — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA48-20MU | ATMEGA48PA-MU | ATMEGA88-20MU | ATMEGA328P-MU |
|---|---|---|---|---|---|
| Package | 32-VQFN (5x5 mm) exposed pad | 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 | 4 KB | 4 KB | 4 KB | 8 KB | 32 KB |
| SRAM | 512 B | 512 B | 512 B | 1 KB | 2 KB |
| EEPROM | 256 B | 256 B | 256 B | 512 B | 1 KB |
| Max Clock Frequency | 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 |
| ADC | 8-channel 10-bit | 8-channel 10-bit | 8-channel 10-bit | 8-channel 10-bit | 8-channel 10-bit |
| Power Optimization | picoPower family | Standard ATmega48 die | picoPower-optimized (lower sleep current) | Standard | picoPower (P-series) |
| On-Chip Debug | debugWIRE | debugWIRE | debugWIRE | debugWIRE | debugWIRE |
Key Differentiators
- Lowest Flash/RAM in a pin-compatible upgrade ladder (vs ATMEGA328P-MU)
- Standard ATmega48 die cost vs picoPower refresh (vs ATMEGA48PA-MU)
- Full 20 MHz speed grade (vs ATMEGA48V-10MU)
Design Notes
The 32-VQFN package has two VCC pins (4 and 6) plus a separate AVCC pin (18). Connect both VCC pins to the same 5 V (or 3.3 V) rail and never leave either floating; AVCC must be tied to VCC through an LC filter (e.g., 10 uH inductor with 100 nF) when ADC accuracy matters, and must never exceed VCC by more than 0.3 V or the ADC and digital logic can be damaged. Enable the internal brown-out detector at approximately 2.7 V for 5 V systems to guarantee predictable resets during supply dips.
The exposed pad on the underside of the QFN-32 is internally connected to GND and must be soldered to a grounded copper pour with an array of thermal vias - relying on perimeter leads alone gives an unreliable connection and poor ground integrity. Place 100 nF ceramic decoupling capacitors within 2 mm of each VCC pin and an additional 100 nF close to AVCC. AREF needs a 100 nF capacitor to ground when the internal reference is used; add an external reference source there only if ADC ratiometric accuracy to VCC is not required.
The debugWIRE interface shares the RESET pin (PC6, pin 29) with high-voltage programming; once the DWEN fuse is set, normal ISP programming and external reset behavior are disabled until debugWIRE is disabled from the debugger, a step beginners often miss and conclude the chip is dead. Also note RESET is active-low with an internal pull-up - if your circuit drives it, keep the driver open-drain. Clock-source fuses determine whether PB6/PB7 act as XTAL pins or GPIO; changing clock fuses incorrectly can lock out the device, so set them deliberately.
When using the internal 8 MHz RC oscillator, keep digital I/O switching currents (LED matrix, relays) physically separated from the XTAL-free PB6/PB7 area used as GPIO, and route ADC input traces short and away from UART/PWM lines. For crystal operation above 16 MHz, follow the datasheet's load-capacitor guidance (typically 12-22 pF depending on crystal) and place the crystal within 5 mm of pins 7-8 with a ground guard ring to prevent stray coupling from causing startup failures.
Compliance Information
The ATmega48 is offered in Microchip's green (halogen-free/lead-free) package variants per family practice, but explicit RoHS/REACH statements for this exact ordering code were not present in the verified web data and should be confirmed from the Microchip product page certificate documents.
