ATMEGA640-16CU - 8-bit AVR MCU 16MHz 64KB CBGA-100 | Microchip
MPN: ATMEGA640-16CU ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $11.67 | $11.67 |
| 10 | $10.74 | $107.40 |
| 25 | $10.28 | $257.00 |
| 100 | $9.42 | $942.00 |
| 1,000 | $8.61 | $8,610.00 |
ATMEGA640-16CU Overview
An 8-bit microcontroller is an integrated circuit that executes instructions and controls peripheral devices using an 8-bit-wide data bus. The AVR ATmega family belongs to the broader taxonomy of embedded processors under the microcontroller (MCU) category, sitting alongside Microchip's PIC and SAM product lines. MCUs integrate CPU, memory, and peripherals on a single die, making them the foundation of embedded system design.
Key features of the ATMEGA640-16CU include a 16MHz AVR RISC core delivering up to 16 MIPS, 64KB self-programmable FLASH with a dedicated boot section supporting in-system programming, and rich connectivity: four USARTs, one master/slave SPI interface, and one byte-oriented 2-wire serial interface (TWI/I2C). The device also integrates a programmable watchdog timer with a separate on-chip oscillator and an on-chip analog comparator.
Technical depth: the AVR architecture uses a Harvard structure with single-cycle instruction execution, and the ATmega640 shares its die family with the ATmega1280 and ATmega2560 (64K/128K/256K Bytes In-System Programmable Flash per the datasheet title). Peripherals include an 8/16-channel 10-bit ADC and an output compare modulator.
Typical applications include industrial automation controllers, 3D printer mainboards, embedded networking nodes, and test and measurement equipment, where the many USARTs and I/O ports simplify multi-channel designs.
Design consideration: this part runs from a 4.5V to 5.5V supply only, so 3.3V designs require the V variants or level shifting; verify CBGA assembly capability before layout.
This page synthesizes verified distributor data, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ATMEGA640-16CU — 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 ATMEGA640-16CU (same form factor and footprint) — differing in Serial Interfaces, USART, Mounting Type, EEPROM, Flash Memory.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ATMEGA1280-16CU
✅ Drop-In✓ In Stock
$12.9 / Unit
View Datasheet →ATMEGA2560-16CU
✅ Drop-In✓ In Stock
$11.75 / Unit
View Datasheet →ATMEGA1280-16CUR
✅ Drop-In✓ In Stock
$6.25 / Unit
View Datasheet →ATMEGA2560-16CUR
✅ Drop-In📋 Reference alternative (not in catalog)
ATMEGA640-16CU Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit AVR RISC |
| Maximum Clock Frequency | 16 MHz |
| Program Memory Size (FLASH) | 64KB (32K x 16) |
| Program Memory Type | In-System Programmable FLASH |
| SRAM Size | 8KB |
| EEPROM Size | 4KB |
| Supply Voltage Range | 4.5 V to 5.5 V |
| I/O Ports / Lines | 53 I/O |
| Number of USARTs | 4 |
| ADC Resolution | 10-bit |
| ADC Channels | 8/16-channel (per datasheet family description) |
| Serial Interfaces | SPI, 2-wire (I2C-compatible TWI), USART |
| Watchdog Timer | Programmable, separate on-chip oscillator |
| Analog Comparator | On-chip |
| Package | 100-CBGA (9x9 mm) |
| Mounting Type | Surface Mount |
| Operating Temperature | Industrial temperature range (-40C to +85C) |
| Data Bus Width | 8 Bit |
| RoHS / Green Status | Green package |
| Debug / Programming | ICSP via 2 I/O pins plus reset (MPLAB SNAP compatible) |
ATMEGA640-16CU 100-cbga (9x9 mm) Pin Configuration Guide
Pin configuration for ATMEGA640-16CU (100-cbga (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 ATMEGA640-16CU.
Refer to the datasheet for full pin configuration.
Typical Applications
ATMEGA640-16CU is suitable for 6 applications: Industrial Automation Controllers, 3D Printer and CNC Motion Control, Embedded Networking Nodes, Test and Measurement Instrumentation, Building Automation and HVAC Control, Security and Access Control Systems.
Industrial Automation Controllers
The ATMEGA640-16CU fits industrial PLC-style controllers because it combines 53 I/O lines, four USARTs, and a 10-bit ADC on one 5V-tolerant die. The 4.5V to 5.5V supply range gives high noise margin on factory floors where 24V logic environments generate significant switching noise, and the programmable watchdog timer with its separate on-chip oscillator recovers the MCU from latch-up or firmware hangs without external components. In a typical controller, USART channels 0 and 1 handle Modbus RTU and HMI communication while the ADC reads analog sensor channels through the analog multiplexer. The 64KB FLASH accommodates a full control loop plus bootloader for field updates, and the 8KB SRAM holds buffered process data. The 100-CBGA (9x9 mm) package keeps the PCB footprint compact for DIN-rail mounted boards.
Recommended
3D Printer and CNC Motion Control
Open-source 3D printer and CNC mainboards historically use the ATmega2560 in 100-pin packages, and the ATMEGA640-16CU is the same die family with 64KB FLASH, making it a cost-reduced option for firmware that fits within 64KB. The four USARTs drive multiple stepper drivers' UART configurations, a host USB-serial bridge, and an SD-card auxiliary channel simultaneously. The 16MHz AVR core executes the stepping ISR with deterministic single-cycle instructions, and the 10-bit ADC reads thermistors for hot-end and bed temperature control. The output compare modulator and multiple timers generate precise step pulses. Because the CBGA package is electrically identical to the TQFP variants used in classic RAMBo-class boards, firmware such as Marlin ports directly with pin-map changes only.
Recommended
Embedded Networking Nodes
Multi-protocol sensor and gateway nodes benefit from the ATMEGA640-16CU's four independent USARTs: one for RS-485 field bus, one for a cellular or LoRa modem, one for a local display, and one reserved for debug. The byte-oriented 2-wire serial interface (TWI, I2C-compatible) attaches EEPROMs, RTCs, and sensor hubs on a shared bus, while the master/slave SPI interface services high-throughput peripherals such as SD cards or Ethernet MACs via SPI-attached controllers. The 8KB SRAM provides adequate buffering for packet assembly at low-to-medium throughput. Operating at 16MHz from a 5V rail simplifies interfacing with 5V RS-485 transceivers without level shifting. The watchdog timer ensures autonomous recovery of unattended remote nodes.
Recommended
Test and Measurement Instrumentation
Bench instruments and data loggers use the ATMEGA640-16CU's 10-bit ADC with its 8/16-channel multiplexer to scan multiple analog inputs, while the on-chip analog comparator provides fast threshold detection for events that would otherwise need an external comparator. The 16MHz core services a menu-driven UI over SPI or TWI displays and streams readings over USART. The 4KB EEPROM stores calibration constants across power cycles, an essential feature for measurement accuracy, and the separate-on-chip-oscillator watchdog guarantees logging continuity. Because the whole ATmega640/1280/2560 family shares one datasheet and register map, designs can migrate to the 128KB or 256KB FLASH parts when logging firmware grows, using the same 100-CBGA footprint and PCB.
Recommended
Building Automation and HVAC Control
Zone controllers and HVAC boards exploit the ATMEGA640-16CU's large I/O count to drive dampers, relays, and fan controls directly from port pins with only transistor buffers, while the 10-bit ADC reads NTC temperature sensors on multiple zones. The TWI bus connects humidity and pressure sensor ICs and real-time clocks for scheduling, and a USART implements BACnet-MS/TP or simple ASCII protocol links to a supervisory controller. The 5V supply rail matches common opto-isolated and relay-driver circuits, reducing component count. The 64KB FLASH holds scheduling logic, PID loops, and an OTA-capable bootloader, and the 4KB EEPROM preserves setpoints during outages. The industrial temperature rating covers rooftop and mechanical-room environments.
Recommended
Security and Access Control Systems
Door controllers and alarm panels require many monitored inputs and several communication channels concurrently, which maps directly onto the ATMEGA640-16CU's 53 I/O lines and four USARTs. Port pins monitor tamper loops and read keypads via matrix scanning or TWI-attached keypads, while a USART drives an RS-485 panel bus and another a GPRS/IP communicator. The 10-bit ADC supervises battery backup voltage and loop resistance measurements for line supervision. The programmable watchdog timer with a separate on-chip oscillator is critical here: security firmware must self-recover even if the main clock fails, because the panel must not remain unresponsive. The 4KB EEPROM retains user codes, zone definitions, and event logs through power loss, and 64KB FLASH stores a full event-history application.
Recommended
Recommended Products Summary
Engineering reference data for ATMEGA640-16CU — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ATMEGA1280-16CU | ATMEGA2560-16CU | ATMEGA1280-16CUR |
|---|---|---|---|---|
| Package | 100-CBGA (9x9) | 100-CBGA (9x9) - same | 100-CBGA (9x9) - same | 100-CBGA (9x9) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| FLASH Size | 64KB | 128KB | 256KB | 128KB |
| SRAM Size | 8KB | 8KB | 8KB | 8KB |
| EEPROM Size | 4KB | 4KB | 4KB | 4KB |
| Max Clock Speed | 16 MHz | 16 MHz | 16 MHz | 16 MHz |
| Supply Voltage | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V |
| I/O Lines | 53 | 53 | 53 | 53 |
Key Differentiators
- Lowest-cost member of the 100-pin CBGA family (vs ATMEGA2560-16CU)
- Four USARTs in a single 8-bit MCU (vs ATMEGA1280-16CU)
- Trade-off: 5V-only operation (vs ATMEGA2560V-8AI)
Design Notes
The 100-CBGA (9x9 mm) package requires a BGA-capable assembly process: define an accurate 0.8/1.0 mm pitch ball land pattern per the datasheet mechanical drawing, and route inner fanout with micro-vias or via-in-pad if layer count allows. CBGA packages have a different CTE than FR-4, so on large boards consider underfill or follow the manufacturer's reliability guidelines for thermal cycling environments. If your contract manufacturer cannot do CBGA rework, consider the pin-equivalent TQFP-100 ATMEGA640-16AUR for easier prototyping.
This is a 5V-only part (4.5V to 5.5V per DigChip specs). Decouple every VCC/VDD ball pair with 100nF ceramics placed as close to the package as the BGA fanout allows, plus bulk 10uF near the supply entry. If mixed with 3.3V peripherals, add series resistors or level translators on the 53 I/O lines; AVR input thresholds at 5V are ~0.6*VCC, so 3.3V drive is marginal-high only for Schmitt-buffered inputs. The separate on-chip oscillator watchdog keeps running even if the main crystal stops, so enable it in production firmware.
Do not confuse suffixes: -16CU is CBGA, -16AU/-16AUR is TQFP-100; they are electrically the same die but NOT footprint-compatible. The ATmega640/1280/2560 share one datasheet, so always check the family table for register differences rather than assuming 1:1 with smaller ATmegas. JTAG and ICSP share some pins - disable JTAG via fuse if those pins are needed as GPIO. Program FLASH endurance and erase/write cycle limits are family-specified in the datasheet; log EEPROM wear if you write calibration data frequently.
Compliance Information
FindIC listing describes the ATMEGA640-16CU as GREEN package and industrial temperature, indicating RoHS-compliant green packaging; REACH, lead-free, and halogen details were not explicitly stated in the provided data.
