ATMEGA325P-20MU - 8-bit AVR MCU 32KB 20MHz 64-QFN | Microchip
MPN: ATMEGA325P-20MU β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.42 | $3.42 |
| 10 | $3.08 | $30.80 |
| 100 | $2.74 | $274.00 |
| 500 | $2.48 | $1,240.00 |
| 1,000 | $2.21 | $2,210.00 |
ATMEGA325P-20MU Overview
A microcontroller unit (MCU) is a single-chip computer that integrates a processor core, program memory, data memory, and peripherals such as ADCs, timers, and communication interfaces. Within the semiconductor hierarchy, the ATmega325P belongs to the AVR ATmega family of 8-bit MCUs, positioned above small AVR tinyAVR parts and below 32-bit ARM-based MCUs in complexity, and serves as the central control element in embedded systems.
Key features include an advanced RISC architecture with 131 powerful instructions, most executing in a single clock cycle; an 8-channel 10-bit ADC; a JTAG interface for on-chip debugging; and In-Circuit Serial Programming (ICSP) for field updates. The picoPower technology delivers low active and sleep current, making the P-variant more efficient than the earlier non-P ATmega325.
Technically, the ATmega325P executes up to 20 MIPS at 20 MHz, and the -20 speed suffix requires a 4.5 V to 5.5 V supply, while the wider AVR ATmega family supports 1.8 V to 5.5 V operation at reduced clock rates. Self-programming Flash enables bootloaders, and 1024 bytes of EEPROM retain calibration data through power cycles.
Typical applications include industrial control panels, consumer appliance control, sensor data loggers, and low-cost instrumentation where a 5 V logic environment and mature AVR tooling are preferred.
For design, remember that a 20 MHz clock requires the 5 V supply range; below 4.5 V the maximum safe clock frequency drops, so derate the crystal accordingly. Use the JTAG header or MPLAB SNAP for on-chip debug during development.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA325P-20MU 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 ATMEGA325P-20MU (same form factor and footprint) β differing in EEPROM, Package.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
ATMEGA325PA-20MU
β Drop-Inπ Reference alternative (not in catalog)
ATMEGA325P-20MUR
β Drop-Inβ In Stock
$2.86 / Unit
View Datasheet βATMEGA325P-20MI
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA325-20MU
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
ATMEGA325P-20MU Maximum Ratings & Electrical Characteristics
| Core Architecture | AVR 8-bit RISC |
| Core Size | 8-bit |
| Maximum Clock Frequency | 20 MHz |
| Throughput | 20 MIPS at 20 MHz |
| Flash Program Memory | 32 KB (16K x 16) |
| SRAM | 2 KB |
| EEPROM | 1 KB (1024B) |
| Supply Voltage Range (family) | 1.8 V to 5.5 V |
| Supply Voltage Range (20 MHz grade) | 4.5 V to 5.5 V |
| ADC | 8-channel 10-bit |
| Debug / Programming Interface | JTAG, ICSP |
| Package | 64-VFQFN Exposed Pad (9x9 mm) |
| Mounting Type | Surface Mount |
| Programming Features | Self-programming Flash, In-System Programmable |
| Instruction Set | 131 instructions, mostly single-cycle |
| Lifecycle Status | ACTIVE |
ATMEGA325P-20MU 64-vfqfn exposed pad (9x9 mm) Pin Configuration Guide
Pin configuration for ATMEGA325P-20MU (64-vfqfn exposed pad (9x9 mm) package). This digital IC includes GPIO, communication interfaces (UART, SPI, I2C), and power pins. Refer to the manufacturer datasheet for alternate pin functions and configuration options. Essential for embedded system design and PCB layout.
No detailed pinout data available for ATMEGA325P-20MU.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA325P-20MU is suitable for 6 applications: Industrial Control Panels, Sensor Data Loggers, Consumer Appliance Control, Low-Cost Instrumentation, Automotive Aftermarket & Accessory Modules, LED Lighting Controllers.
Industrial Control Panels
The ATMEGA325P-20MU fits industrial control panels because its 4.5 V to 5.5 V supply range matches legacy 5 V industrial logic, and 20 MIPS throughput handles state machines, relay sequencing, and HMI polling with margin. The 8-channel 10-bit ADC digitizes potentiometers, current-shunt signals, and temperature sensors directly, while 1 KB EEPROM stores calibration and trip-limit data across power cycles. JTAG on-chip debugging accelerates firmware bring-up on panel prototypes. Placed as the main controller with ICSP header for field firmware updates, the device runs reliably from unregulated industrial supplies after simple linear or buck regulation; its exposed-pad VFQFN aids heat spreading in sealed enclosures.
Recommended
Sensor Data Loggers
For battery-backed data loggers, the ATMEGA325P-20MU's picoPower sleep modes and 1 KB EEPROM allow periodic sampling with data retention. The 8-channel 10-bit ADC multiplexes multiple analog sensors without external front-ends, and 2 KB SRAM buffers logged records before writing to external EEPROM or SD media over SPI. Designers typically run the part from 2x AA cells through a boost regulator, waking on timer or pin-change interrupt, sampling, then sleeping to cut average current. Note that the 20 MHz grade requires 5 V, so loggers running below 4.5 V should derate clock speed per the AVR frequency-voltage curve. Self-programming Flash supports field-updatable logging firmware in deployed units.
Recommended
Consumer Appliance Control
White goods and small appliances use the ATMEGA325P-20MU as the main control MCU because its 5 V operation, 32 KB Flash, and rich timer set cover motor timing, user-interface scanning, and safety interlock logic in one chip. The 64-pin VFQFN provides enough I/O to drive seven-segment displays, relays, and touch keys simultaneously without port expanders, reducing BOM cost. Firmware benefits from 131 mostly single-cycle AVR instructions for deterministic button-scan and PWM loops. The JTAG interface supports production-line programming and in-circuit diagnosis, while self-programming Flash allows service-bootloader updates. Its active lifecycle status ensures long-term availability for multi-year appliance programs.
Recommended
Low-Cost Instrumentation
Bench and portable instruments exploit the ATMEGA325P-20MU's deterministic 8-bit core and integrated peripherals to replace discrete glue logic. The 10-bit ADC with 8 input channels captures front-panel settings and measurement channels, while hardware timers generate precise gate windows and PWM reference signals. With 20 MHz operation at 5 V, the MCU delivers timing resolution of 50 ns per cycle for counter and frequency-meter functions. The JTAG port allows engineers to single-step measurement firmware during calibration, and EEPROM retains gain and offset constants between sessions. The exposed-pad 9x9 mm VFQFN keeps the controller compact on crowded analog boards without sacrificing routability.
Recommended
Automotive Aftermarket & Accessory Modules
In non-safety automotive accessory modules such as lighting controllers, window retrofit kits, and gauge adapters, the ATMEGA325P-20MU provides robust 5 V control tolerant of automotive 12 V rails after a simple regulator, with the industrial-temperature ATMEGA325P-20MI grade available for harsher cabin and engine-bay environments. Its ADC reads potentiometer and sensor feedback, timers drive lamp PWM dimming, and EEPROM stores learned vehicle configurations. The 64-pin footprint supplies ample I/O for CAN-toolιδ»Ά or discrete signaling, and ICSP supports end-of-line flashing. Note that the standard ATmega325P is not AEC-Q100 qualified, so certified automotive programs must use qualified Microchip automotive AVR parts instead.
Recommended
LED Lighting Controllers
Dimmable LED drivers and smart-lamp controllers use the ATMEGA325P-20MU's hardware timers to generate phase-cut or PWM dimming signals with 50 ns cycle resolution at 20 MHz. The 10-bit ADC samples dimmer potentiometers, ambient-light sensors, and current-shunt feedback for closed-loop brightness regulation, while the 5 V logic simplifies interfacing with triac driver optocouplers. With 32 KB Flash, the MCU implements smooth gamma-corrected fading curves, DALI-like protocol handlers, and temperature foldback protection in a single chip. PicoPower sleep modes keep standby power low for always-plugged fixtures. The VFQFN exposed pad grounds the controller thermal path, improving reliability in enclosed, passively cooled lamp housings.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA325P-20MU β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA325PA-20MU | ATMEGA325P-20MUR | ATMEGA325P-20MI | ATMEGA325P-20AU |
|---|---|---|---|---|---|
| Package | 64-VFQFN (9x9 mm) exposed pad | 64-VFQFN (9x9 mm) - same | 64-VFQFN (9x9 mm) - same | 64-VFQFN (9x9 mm) - same | TQFP-64 - different footprint |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 32 KB | 32 KB | 32 KB | 32 KB | 32 KB |
| SRAM | 2 KB | 2 KB | 2 KB | 2 KB | 2 KB |
| Max Clock Speed | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Power Technology | picoPower (P) | picoPower A - lowest power | picoPower (P) | picoPower (P) | standard (higher power) |
| Debug Interface | JTAG + ICSP | JTAG + ICSP | JTAG + ICSP | JTAG + ICSP | JTAG + ICSP |
| Lifecycle Status | ACTIVE | ACTIVE | ACTIVE | ACTIVE | ACTIVE |
Key Differentiators
- Lowest power in the 32 KB 64-QFN ATmega family (vs ATMEGA325-20MU)
- JTAG on-chip debug on a sub-4 USD MCU (vs ATMEGA324P-20AUR)
- Even lower power A-variant available with zero redesign (vs ATMEGA325PA-20MU)
- Trade-off: no AEC-Q100 qualification (vs ATMEGA16M1-15MD)
Design Notes
The ATMEGA325P-20MU operates at full 20 MHz only from a 4.5 V to 5.5 V supply. If your rail sags below 4.5 V during inrush or brownout, the AVR may overclock relative to its rating and corrupt execution. Add a supply monitor or brown-out detector (the AVR internal BOD can be fused on) and verify the 5 V rail under worst-case load. For 3.3 V systems, switch to a low-voltage V-series ATmega with a reduced clock instead of forcing this speed grade.
The 64-VFQFN exposed pad is the primary ground and thermal path. Solder the center pad to a grounded copper pour with an array of thermal vias - do not leave it floating, as QFN center pads are prone to incomplete wetting with excessive paste. Use a window-pane stencil covering roughly 50-70% of the pad area. Decouple VCC and AVCC each with 100 nF ceramics placed within 2 mm of the pins, plus 10 uF bulk at the supply entry.
Route XTAL1/XTAL2 crystal traces short (under 10 mm) and guard them with ground pour to keep the 20 MHz oscillator stable against switching noise from the ADC and outputs. Keep analog sensor traces away from the crystal and PWM outputs, and connect AGND/DGND at a single point near the exposed pad. If JTAG is used in production for boundary scan or debug, reserve the four JTAG pins with 100-ohm series resistors to protect them from contention.
Two frequent errors with this part: first, assuming the family 1.8 V to 5.5 V range applies at 20 MHz - it does not; the -20 grade needs 5 V. Second, forgetting that JTAG pins overlap general-purpose I/O: if your firmware expects full port width, disable JTAG via fuse after production programming, otherwise PC port pins remain unavailable. Also verify EEPROM wear leveling if logs write every second - 1 KB EEPROM endurance is finite.
Compliance Information
RoHS/lead-free per current Microchip AVR production standards; confirm certificate on the Microchip product page. REACH, halogen-free, and conflict-minerals status not stated in provided data.