ATMEGA48A-MMH - 8-Bit AVR MCU, 4KB Flash, 20MHz | Microchip
MPN: ATMEGA48A-MMH ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.42 | $1.42 |
| 10 | $1.28 | $12.80 |
| 100 | $1.1 | $110.00 |
| 500 | $0.98 | $490.00 |
| 1,000 | $0.86 | $860.00 |
ATMEGA48A-MMH Overview
An AVR ATmega microcontroller is a Harvard-architecture 8-bit MCU in the broader product hierarchy of microcontroller unit (MCU) -> embedded processor -> semiconductor integrated circuit. AVR cores use a load/store architecture with 32 general-purpose working registers directly connected to the ALU, allowing most of the 131 instructions to execute in a single clock cycle, which yields throughput of up to 20 MIPS at 20MHz while minimizing power consumption.
Key features include 4KB self-programmable ISP Flash organized as 2K x 16 with 10,000 write cycles, an on-chip 8-channel 10-bit ADC, three flexible timer/counters with compare modes, and a byte-oriented two-wire serial interface (I2C-compatible TWI) alongside SPI and USART. The device operates from 4.5V to 5.5V at 0-20MHz (industrial temperature range) and supports five power-saving sleep modes with an on-chip brown-out detector and power-on reset.
The ATMEGA48A implements the advanced RISC AVR architecture with hardware multiplier, nested interrupt controller, and in-system programmability via SPI. DebugWIRE on-chip debugging is provided through the RESET pin, eliminating the need for a dedicated JTAG port in cost-sensitive designs. The MMH suffix denotes the halogen-free, green 28-VQFN package qualified for industrial temperature.
Typical applications include industrial control and automation nodes, consumer appliances, HVAC and motor-control subsystems, and battery-charged handheld instruments where a compact 4x4 mm footprint and 5V ADC accuracy are required.
Design consideration: at 5V operation the full 20MHz clock range is available, but below 4.5V the maximum safe frequency derates, so match the supply rail to the intended clock speed.
This page synthesizes distributor pricing, drop-in alternatives, FAQ content, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA48A-MMH — 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 ATMEGA48A-MMH (same form factor and footprint) — differing in Communication Interfaces, Timers, Package, EEPROM, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA88A-MMH
✅ Drop-In✓ In Stock
$1.12 / Unit
View Datasheet →ATMEGA168A-MMHR
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.58 / Unit
View Datasheet →ATMEGA48-20MMH
✅ Drop-In📋 Reference alternative (not in catalog)
ATMEGA48PA-MMHR
✅ Drop-In✓ In Stock
$1.62 / Unit
View Datasheet →ATMEGA48A-MMH Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Flash Memory | 4KB (2K x 16) |
| EEPROM | 256B |
| SRAM | 512B |
| Maximum Clock Frequency | 20 MHz |
| Supply Voltage Range | 4.5 V to 5.5 V (at 20 MHz) |
| Number of I/O | 23 |
| ADC Resolution | 10-bit |
| ADC Channels | 8 |
| Timers | 2 x 8-bit, 1 x 16-bit |
| Communication Interfaces | USART, SPI, TWI (I2C-compatible) |
| MIPS Throughput | Up to 20 MIPS at 20 MHz |
| Operating Temperature | -40C to +85C (industrial) |
| Package | 28-VQFN (4x4 mm, 0.45 mm pitch) |
| Mounting Type | Surface Mount |
| Package Height | 1 mm |
| Programming Interface | ISP (SPI), DebugWIRE |
| RoHS Status | Compliant (green package) |
ATMEGA48A-MMH Pin Configuration
| Pin 1 | PD3 (PCINT19/INT1/OC2B/TXD1) — Port D, digital I/O / external interrupt / Timer2 PWM / USART TX (alternate) |
| Pin 2 | PD4 (PCINT20/XCK/T0) — Port D, digital I/O / USART clock / Timer0 input (alternate) |
| Pin 3 | GND — Ground |
| Pin 4 | VCC — Digital supply voltage |
| Pin 5 | GND — Ground |
| Pin 6 | VCC — Digital supply voltage |
| Pin 7 | PB6 (PCINT6/XTAL1/TOSC1) — Port B / crystal oscillator input / Timer oscillator (alternate) |
| Pin 8 | PB7 (PCINT7/XTAL2/TOSC2) — Port B / crystal oscillator output (alternate) |
| Pin 9 | PD5 (PCINT21/XCK1/OC0B/T1) — Port D, digital I/O / Timer0 PWM / Timer1 input (alternate) |
| Pin 10 | PD6 (PCINT22/OC0A/AIN0) — Port D, digital I/O / Timer0 PWM / analog comparator input (alternate) |
| Pin 11 | PD7 (PCINT23/AIN1) — Port D, digital I/O / analog comparator input (alternate) |
| Pin 12 | PB0 (PCINT8/ICP1/CLKO) — Port B, digital I/O / Timer1 capture / clock output (alternate) |
| Pin 13 | PB1 (PCINT9/OC1A) — Port B, digital I/O / Timer1 PWM output A (alternate) |
| Pin 14 | PB2 (PCINT10/SS/OC1B) — Port B, digital I/O / SPI slave select / Timer1 PWM output B (alternate) |
| Pin 15 | PB3 (PCINT11/OC2A/MOSI) — Port B, digital I/O / Timer2 PWM / SPI MOSI (alternate) |
| Pin 16 | PB4 (PCINT12/MISO) — Port B, digital I/O / SPI MISO (alternate) |
| Pin 17 | PB5 (PCINT13/SCK) — Port B, digital I/O / SPI clock (alternate) |
| Pin 18 | AVCC — ADC supply voltage |
| Pin 19 | ADC6 — Analog input channel 6 |
| Pin 20 | AREF — ADC analog reference |
| Pin 21 | GND — Ground |
| Pin 22 | ADC7 — Analog input channel 7 |
| Pin 23 | PC0 (PCINT16/ADC0) — Port C, digital I/O / ADC channel 0 (alternate) |
| Pin 24 | PC1 (PCINT17/ADC1) — Port C, digital I/O / ADC channel 1 (alternate) |
| Pin 25 | PC2 (PCINT18/ADC2) — Port C, digital I/O / ADC channel 2 (alternate) |
| Pin 26 | PC3 (PCINT19/ADC3) — Port C, digital I/O / ADC channel 3 (alternate) |
| Pin 27 | PC4 (PCINT20/ADC4/SDA) — Port C, digital I/O / ADC channel 4 / TWI data (alternate) |
| Pin 28 | PC5 (PCINT21/ADC5/SCL) — Port C, digital I/O / ADC channel 5 / TWI clock (alternate) |
Typical Applications
ATMEGA48A-MMH is suitable for 6 applications: Industrial Control and Automation Nodes, Home Appliance and HVAC Control Boards, Motor Control Subsystems (Small DC/Stepper), Battery-Charged Handheld Instruments, IoT Sensor End Nodes (Wired Backhaul), Consumer Electronics Human-Interface Controllers.
Industrial Control and Automation Nodes
The ATMEGA48A-MMH fits industrial sensor and actuator nodes where a 5V logic rail, -40C to +85C operation, and a compact 4x4 mm footprint coexist. Its 8-channel 10-bit ADC reads analog transducers (thermistors, potentiometers, 4-20mA conditioners) directly at 5V full-scale, avoiding external level shifting, while the three timer/counters generate PWM for relays, valves, or small motors. The brown-out detector and power-on reset guarantee deterministic startup on noisy industrial supplies. Communication to a PLC or supervisory controller uses the USART (RS-485 via external transceiver) or TWI bus. At 20MHz with 23 I/O lines, a single ATmega48A replaces discrete glue logic, reducing BOM count in control boards.
Recommended
Home Appliance and HVAC Control Boards
Appliance and HVAC controllers value the ATMEGA48A-MMH combination of 5V ADC accuracy, on-chip temperature-capable ADC channels, and self-programmable Flash for field firmware updates. The 4KB Flash comfortably holds state machines for compressor/fan sequencing, keypad scanning, and 7-segment or LCD driving via TWI. The watchdog timer and brown-out reset satisfy basic functional-safety supervision of heating loops. The 28-VQFN (4x4 mm) keeps the PCB small enough for wall-thermostat and control-panel form factors, while the industrial temperature rating tolerates enclosure heat. Sleep modes allow always-on standby displays to meet low standby-power expectations at wall-power budgets.
Recommended
Motor Control Subsystems (Small DC/Stepper)
The hardware PWM outputs of the ATmega48A timers, combined with the 20MHz single-cycle-execution core, provide closed-loop control of small DC motors and steppers. The 16-bit Timer/Counter1 supports phase-correct PWM at audio-above frequencies, and the ADC can sample a current-sense shunt or hall feedback for speed regulation. Running from a 5V rail simplifies interfacing with gate drivers and logic-level MOSFET bridges. The MMH package's exposed pad provides a solid ground return that reduces switching-noise ground bounce. Firmware-level commutation tables fit easily within 4KB, making this MCU a cost-effective controller under a dedicated driver IC.
Recommended
Battery-Charged Handheld Instruments
Handheld meters and test instruments use the ATMEGA48A-MMH for front-panel control, measurement sequencing, and display driving. The 8-channel 10-bit ADC samples battery voltage, user controls, and sensor inputs; EEPROM (256B) stores calibration constants that survive battery replacement. Although the A-version is optimized for 5V, handheld designs with a boost regulator to 5V gain a full 20MHz clock and maximum ADC accuracy. Power-down and power-save sleep modes reduce average current between measurements. DebugWIRE debugging through the RESET pin allows in-enclosure firmware troubleshooting without extra pins, valuable in dense handheld layouts.
Recommended
IoT Sensor End Nodes (Wired Backhaul)
In wired IoT sensor nodes (TWI/SPI sensor front ends, RS-485 backhaul), the ATMEGA48A-MMH aggregates readings from I2C sensors and reports over USART. The 512B SRAM holds protocol buffers for Modbus RTU frames; 4KB Flash stores sensor drivers, Modbus stack, and CRC routines. The 5V I/O tolerates industrial wiring environments better than 3.3V-only MCUs, and the internal pull-ups simplify open-drain bus interfaces. The green, halogen-free 28-VQFN package suits compact, RoHS-driven node designs. For battery-powered wireless nodes, consider the picoPower ATmega48PA variant instead, which shares the same pinout and footprint.
Recommended
Consumer Electronics Human-Interface Controllers
The ATMEGA48A-MMH serves as a low-cost HID controller for buttons, rotary encoders, LEDs, and small displays in consumer products. Its 131-instruction AVR core handles debouncing, menu state machines, and PWM LED dimming (all three timers support PWM) within the 4KB budget. The TWI interface drives I2C OLED or segment drivers, while 23 GPIO lines cover keypad matrices up to 11x12. The 4x4 mm VQFN keeps controller area minimal on dense consumer PCBs, and the industrial temperature grade tolerates enclosure heat near power supplies. Self-programmable Flash enables final-configuration personalization on the production line.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA48A-MMH — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA88A-MMH | ATMEGA168A-MMH | ATMEGA48-20MMH |
|---|---|---|---|---|
| Package | 28-VQFN (4x4 mm) | 28-VQFN (4x4 mm) - same | 28-VQFN (4x4 mm) - same | 28-VQFN (4x4 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 4KB | 8KB | 16KB | 4KB |
| SRAM | 512B | 1KB | 1KB | 512B |
| EEPROM | 256B | 512B | 512B | 256B |
| Max Clock | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Supply Voltage | 4.5 V to 5.5 V (20 MHz) | 4.5 V to 5.5 V (20 MHz) | 4.5 V to 5.5 V (20 MHz) | 4.5 V to 5.5 V (20 MHz) |
| ADC | 10-bit, 8 channels | 10-bit, 8 channels | 10-bit, 8 channels | 10-bit, 8 channels |
| Lifecycle | Active | Active | Active | Legacy (superseded by ATmega48A family) |
Key Differentiators
- Lowest cost entry point of the megaAVR QFN-28 family (vs ATMEGA88A-MMH)
- Newer manufacturing process than legacy ATmega48 (vs ATMEGA48-20MMH)
- 5V-optimized timing and ADC full-scale accuracy (vs ATMEGA48PA-MMHR)
Design Notes
Decouple both VCC pins (4 and 6) with 0.1uF ceramic capacitors placed within 3 mm of each pin, plus a 4.7-10uF bulk capacitor near the package. AVCC (pin 18) must be connected to VCC even if the ADC is unused; filter it through an LC network (10uH + 100nF) when ADC accuracy matters, since AVCC noise directly appears as ADC reference noise. Estimated: at 20MHz, 5V, typical active current is in the several-mA range per the datasheet electrical characteristics; verify exact figures in the family datasheet for your supply budget.
The exposed pad underneath the 28-VQFN is the main ground connection - solder it to a stitched ground plane, not just thermal relief vias, to guarantee ground integrity and ADC performance. The 0.45 mm pitch requires accurate solder paste apertures (approximately 90% stencil scale) to avoid bridging. If using a crystal on PB6/PB7, keep trace length under 10 mm and place 12-22 pF load capacitors close to the pins; the internal RC oscillator (8 MHz factory-calibrated) avoids this entirely for non-timing-critical designs.
Two frequent migration mistakes: (1) DebugWIRE shares the RESET pin - once DWEN fuse is set, an external programmer cannot reset the chip normally and recovery requires a DebugWIRE-aware tool; leave DWEN unset in production. (2) Clock safety: the 20MHz rating applies only at 4.5-5.5V. Running near the voltage floor at full speed violates the frequency-vs-voltage curve and causes intermittent failures, especially at temperature extremes. Also remember ATmega48A lacks the 8KB+ boot-section features; ISP programming uses the standard SPI interface on PB3/PB4/PB5.
Compliance Information
Distributor listings describe the MMH package as GREEN (halogen-free, RoHS). REACH and conflict-minerals declarations were not present in the retrieved data.
