ATMEGA48A-MMHR - 4KB AVR MCU, 20MHz, VQFN-28 | Microchip
MPN： ATMEGA48A-MMHR ✓ 啟用中ATMEGA48A-MMHR 概覽
An 8-bit AVR microcontroller is a single-chip computer built around an advanced RISC core in which most of the 131 instructions execute in a single clock cycle. Within the power-management hierarchy, it integrates the CPU, program memory, data memory, timers, and peripherals into one semiconductor device, replacing multi-chip processor-plus-memory designs in cost-sensitive embedded systems.
Key differentiating features include 32 general-purpose working registers directly connected to the ALU for single-cycle execution, three flexible timer/counters with compare modes, and In-System Programmable (ISP) Flash that allows firmware updates on the assembled PCB. The 4 KB self-programmable Flash, organized for both code and data storage, suits compact firmware images typical of sensor nodes and small appliances.
Architecturally, the AVR core couples a load-store Harvard memory structure with the large register file, achieving throughput of up to 20 MIPS at 20 MHz while remaining low power. Hardware multiply, interrupt-driven peripherals, and programmable watchdog complete the core subsystem, and the A-grade silicon is a drop-in functional replacement for the original ATmega48/88/168 family per Microchip application note AVR532.
Typical applications include consumer appliance control, small industrial sensor nodes, battery-powered handheld devices, and lighting or HVAC control boards where a compact 4x4 mm footprint and low cost dominate.
A key design consideration: at 20 MHz the part requires a 4.5 V to 5.5 V supply for full-speed operation, while lower clock frequencies permit reduced supply voltage, so verify the frequency-versus-voltage derating curve in the datasheet before fixing the rail.
This page synthesizes distributor pricing context, verified drop-in alternatives within the ATmega family, and practical design notes not consolidated in the manufacturer datasheet. Pricing below is as of 2026-09-18.
直接替換替代品，適用於 ATMEGA48A-MMHR — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： ATMEGA48A-MMHR （相同外形與佔位） — 差異在於 Package, SRAM, RoHS Status, Communication Interfaces, Flash Memory.
ATMEGA48PA-MMHR
✅ 直接替換聯絡詢價
查看資料表 →ATMEGA48-20MMH
✅ 直接替換📋 參考替代品（不在目錄中）
ATMEGA88A-MMHR
✅ 直接替換 ⚠️ 規格未經驗證聯絡詢價
查看資料表 →ATMEGA168A-MMHR
✅ 直接替換 ⚠️ 規格未經驗證聯絡詢價
查看資料表 →ATMEGA328-MMHR
✅ 直接替換 ⚠️ 規格未經驗證聯絡詢價
查看資料表 →ATMEGA48A-MMHR 最大額定值與電氣特性
| Core Architecture | 8-bit AVR RISC |
| Core Frequency | 20 MHz |
| Flash Memory | 4 KB (2K x 16) ISP Flash |
| EEPROM | 256 B |
| SRAM | 512 B |
| General Purpose I/O | 23 lines |
| Working Registers | 32 x 8-bit |
| Instructions | 131 instructions, most single-cycle |
| Timer/Counters | 3 flexible timer/counters with compare modes |
| Supply Voltage (min, reduced speed) | 1.8 V |
| Supply Voltage (full 20 MHz speed) | 4.5 V to 5.5 V |
| 封裝 | 28-VQFN (4x4 mm), 0.45 mm pitch, 1.0 mm height |
| 安裝類型 | Surface Mount |
| 生命週期狀態 | Active |
| Programmability | In-System Programmable (ISP) Flash |
ATMEGA48A-MMHR 28-vqfn (4x4 mm), 0.45 mm pitch, 1.0 mm height 腳位配置指南
ATMEGA48A-MMHR（28-vqfn (4x4 mm), 0.45 mm pitch, 1.0 mm height 封裝）的腳位配置。 此數位 IC 包含 GPIO、通訊介面（UART、SPI、I2C）與電源腳位。替代腳位功能與配置選項請參閱製造商資料表。對嵌入式系統設計與 PCB 佈局至關重要。
無詳細腳位定義資料： ATMEGA48A-MMHR.
請參閱 資料表 以查看完整腳位配置。
典型應用
ATMEGA48A-MMHR 適用於 6 應用s: Consumer Appliance Control, Industrial Sensor Nodes, Lighting and HVAC Control Boards, Battery-Powered Handheld Devices, Hobby and Educational Embedded Platforms, Small Motor and Actuator Drivers.
Consumer Appliance Control
Small appliances such as coffee makers, fans, and rice cookers need a low-cost controller that reads a few buttons and sensors and drives relays or triacs. The ATMEGA48A-MMHR fits this role with its 23 GPIO lines, three timer/counters with compare modes for PWM generation, and 4 KB Flash that is ample for control loops and UI logic. Its 4x4 mm VQFN footprint lets designers place the MCU directly under or beside the user-interface PCB without a dedicated controller area, cutting board cost. The 20 MHz AVR core executes 131 mostly single-cycle instructions, providing headroom for button debouncing, temperature filtering, and safety interlocks in a single compact 8-bit microcontroller.
推薦
Industrial Sensor Nodes
Wired industrial sensor nodes benefit from the ATMEGA48A-MMHR's combination of 23 I/O lines, on-chip ADC-capable port structure, and 256 B EEPROM for storing calibration constants that survive power cycles. The 512 B SRAM handles modest filtering buffers for temperature, pressure, or proximity readings, while the three timer/counters generate measurement gates and PWM outputs. Its ISP Flash allows field firmware updates over SPI without desoldering the device - a practical advantage during production-line revisions. Running from a 5 V industrial rail at 4.5 V to 5.5 V, the 20 MHz core provides fast interrupt response for pulse-capture tasks, and the small 4x4 mm package fits compact terminal-block mounted adapter boards.
推薦
Lighting and HVAC Control Boards
Dimming, fan-speed, and damper control demand precise multi-channel PWM, which the ATMEGA48A-MMHR delivers through its three timer/counters with compare modes at up to 20 MHz resolution. The 5 V operating range aligns directly with legacy 12 V/5 V lighting power trees after simple regulation, and the 4 KB Flash accommodates scheduling, ramping, and NTC-lookup firmware with room to spare. Its 28-VQFN 4x4 mm body allows placement on dense wall-control PCBs where a DIP MCU would not fit. Because the AVR architecture executes most of its 131 instructions in one cycle, deterministic PWM updates and button scanning run reliably even with conservative interrupt latencies, simplifying EMC-compliant dimming designs.
推薦
Battery-Powered Handheld Devices
When the battery-compatible ATMEGA48PA variant is substituted (same 28-VQFN footprint), the platform suits handheld meters, tags, and remote controls. The base ATMEGA48A-MMHR itself fits mains- or cradle-charged handhelds where a 5 V rail exists. In either case, the 23 GPIO lines drive segmented LCD or LED indicators and scan keypads, while the 256 B EEPROM preserves user settings and usage counters between sessions. The low-power AVR core idles between tasks using timer interrupts, and the compact 4x4 mm, 1 mm-height package slides into slim enclosure constraints. Designers should verify the frequency-versus-voltage derating curve before running reduced-voltage batteries, since full 20 MHz speed requires 4.5 V to 5.5 V.
推薦
Hobby and Educational Embedded Platforms
The ATmega48A family is a staple of embedded-systems education and maker projects because its AVR core matches the widely documented Arduino architecture while keeping cost minimal. The ATMEGA48A-MMHR's 4 KB Flash is enough for introductory C programs covering GPIO, interrupts, timers, and ADC exercises, and the 32 working registers make assembly teaching straightforward. ISP programming over SPI uses a simple 6-wire header, so students can flash code from free toolchains without dedicated programmers. The 28-VQFN package teaches modern surface-mount assembly, while socketed TQFP/DIP siblings in the same family support breadboard prototyping before committing to the compact 4x4 mm production footprint.
推薦
Small Motor and Actuator Drivers
Small DC and stepper motors in printers, locks, and dosing pumps need coordinated PWM plus direction and limit-switch I/O. The ATMEGA48A-MMHR provides 23 GPIO lines for H-bridge gating and feedback inputs, and its timer/counters with compare modes generate phase-correct PWM for smooth low-speed torque control. Running at 20 MHz gives 50 ns PWM edge resolution at typical 20 kHz switching frequencies, well beyond the needs of small actuators. The 512 B SRAM supports ramp tables and step sequencing, and the watchdog timer adds fail-safe shutdown for jammed-mechanism conditions. Its 4 KB Flash holds commutation, protection, and communication firmware within the compact 4x4 mm VQFN footprint.
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推薦產品摘要
工程參考資料，適用於 ATMEGA48A-MMHR — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | ATMEGA48PA-MMHR | ATMEGA48-20MMH | ATMEGA88A-MMHR | ATMEGA168A-MMHR | ATMEGA328-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 | 4 KB ISP Flash | 4 KB | 4 KB | 8 KB | 16 KB | 32 KB |
| SRAM | 512 B | 512 B | 512 B | 1 KB | 1 KB | 2 KB |
| EEPROM | 256 B | 256 B | 256 B | 512 B | 512 B | 1 KB |
| Max Clock Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| GPIO Count | 23 | 23 | 23 | 23 | 23 | 23 |
| Key Differentiator | Cost-optimized 4 KB A-grade AVR | picoPower low sleep current | original process revision | 2x Flash, bootloader support | 4x Flash | 8x Flash, Arduino-class memory |
主要差異化特點
- Lowest-cost entry point of the 28-VQFN ATmega family (對比ATMEGA328-MMHR)
- Same footprint with a picoPower sibling available (對比ATMEGA48PA-MMHR)
- Modern A-process silicon (對比ATMEGA48-20MMH)
設計說明
The ATMEGA48A-MMHR needs 4.5 V to 5.5 V for full 20 MHz operation. If your rail is 3.3 V, either reduce the clock per the datasheet frequency-versus-voltage derating curve or switch to the pin-compatible ATMEGA48PA-MMHR, which supports 1.8 V to 5.5 V. Decouple VCC and AVCC with 100 nF ceramics placed within 2 mm of each pin, and tie AVCC to VCC through a low-pass filter (10R + 100 nF) when ADC accuracy matters. Estimated: at 5 V and 20 MHz with light GPIO loading, active current stays in the low-milliamp region, so thermal design is rarely a concern.
The 28-VQFN (4x4 mm, 0.45 mm pitch) package requires a correct land pattern with an exposed center pad for ground. Sweep the center pad with a via array (4-9 vias of 0.3 mm) to the ground plane to improve solderability and grounding, and apply a solder-paste aperture of roughly 60-70% coverage to prevent floating during reflow. The trailing R in ATMEGA48A-MMHR denotes tape-and-reel for pick-and-place; specify the corresponding land pattern per the Microchip MLF/VQFN application note rather than copying TQFP-32 patterns, since the two footprints differ.
Do not confuse package suffixes: ATMEGA48A-MMH (alternate packing) and ATMEGA48A-MU (32-pad VQFN) are NOT the same footprint - only the 28-pad MMH/MMHR versions share the 4x4 mm, 0.45 mm pitch land pattern. Also remember RESET shares pin PC6; if you enable RSTDISBL to gain an I/O line you permanently disable ISP programming, bricking field updates. Program the SPIEN fuse default and keep a 6-pin ISP header accessible. When migrating firmware between ATmega48A/88A/168A, update the device header and check interrupt vector differences per Microchip app note AVR532.
合規資訊
Distributor packaging data describes a green plastic package typical of Microchip lead-free RoHS parts, but formal RoHS/REACH declarations for this exact MPN were not verified in the provided data as of 2026-09-18. Request the compliance certificate with your quote.
