Atmel Corporation was a creator and manufacturer of semiconductors before being subsumed by Microchip Technology in 2016. Atmel was founded in 1984. The company focused on embedded systems built around microcontrollers. Its products included microcontrollers (8-bit AVR, 32-bit AVR, 32-bit ARM-based, automotive grade, and 8-bit Intel 8051 derivatives) radio-frequency (RF) devices including Wi-Fi, EEPROM, and flash memory devices, symmetric and asymmetric security chips, touch sensors and controllers, and application-specific products. Atmel supplies its devices as standard products, application-specific integrated circuits (ASICs), or application-specific standard product (ASSPs) depending on the requirements of its customers.

Atmel serves applications including consumer, communications, computer networking, industrial, medical, automotive, aerospace and military. It specializes in microcontroller and touch systems, especially for embedded systems.

Atmel's corporate headquarters is in San Jose, California, in the North San Jose Innovation District. Other locations include Trondheim, Norway; Colorado Springs, Colorado; Chennai, India; Shanghai, China; Taipei, Taiwan; Rousset, France; Nantes, France; Patras, Greece; Heilbronn, Germany; Munich, Germany; Whiteley, United Kingdom; Cairo, Egypt. Atmel makes much of its product line at vendor fabrication facilities. It owns a facility in Colorado Springs, Colorado that manufactures its XSense line of flexible touch sensors.

In 2016, Microchip agreed to buy Atmel for US$3.6 (equivalent to $4.72 in 2024) billion in a deal brokered by JPMorgan Chase and Qatalyst.

Atmel Corporation was founded in 1984, by George Perlegos. Atmel was an acronym for "advanced technology for memory and logic". Perlegos had worked in the memory group of Intel in the 1970s and had co-founded Seeq Technology to manufacture EPROM memory. Using only US$30,000 in capital, Atmel was initially operated as a fabless company, using Sanyo and General Instrument to make the chip wafers. The first Atmel memory products used less power than competitors. Customers included Motorola, Nokia, and Ericsson. In 1987, Intel sued Atmel for patent infringement. Rather than fight the patent claim, Atmel redesigned its products to use different intellectual property. These had better performance and even lower power consumption. In addition, Atmel then entered the flash memory business that Intel had focused on. Atmel used US$60 million in venture capital for the 1989 purchase of a fabrication facility from Honeywell in Colorado Springs. Atmel then invested another US$30 million in manufacturing technology.

In 1991, Atmel expanded the Colorado facility after acquiring Concurrent Logic, a field-programmable gate array (FPGA) manufacturer. The company made its initial public offering (IPO) in 1991 which yielded more than US$65 million. 1994 saw Atmel enter the microprocessor market. The first Atmel flash memory microcontroller was based on the Intel 8051. The controller executed an instruction for every clock cycle, as opposed to the 12 cycles that legacy 8051 parts required. In 1994, Atmel purchased the EEPROM assets of Seeq Technology (LSI Corporation acquired the rest of Seeq in 1999). In 1995, Atmel was among the first companies to license the ARM architecture, creating its AT91 family of devices, followed by the SAM family, and more recently a full selection of Cortex-based solutions, including ones based on the ultra-low-power ARM Cortex-M4. Atmel now has dozens of families of ARM-based devices. In 1995, Atmel acquired the pan-European chipmaker European Silicon Structures (ES2) and thus gained a fabrication facility in Rousset, France. Atmel built a new fab alongside the existing ES2 fab. This business unit was named Atmel-ES2. Atmel acquired Digital Research in Electronic Acoustics and Music (DREAM) in 1996. Atmel formed a design team in Trondheim, Norway to develop the Atmel AVR line of RISC microcontrollers. This team combined technology of former students at the Norwegian University of Science and Technology with Atmel's expertise in flash memory. These 8-bit Harvard architecture chips were first developed in 1996. The AVR chip is the basis of most Arduino open-source development boards. In 1998, Atmel purchased part of TEMIC from Vishay Intertechnology, which provided them with a fab in Germany as well as part of MHS from Vishay that gave them a fab in Nantes, France.

In September 2000, Atmel acquired a fabrication plant in North Tyneside, England, from Siemens, via a £28 million grant from the UK government and paying Siemens around US$35 million.

Atmel streamlined operations with a strategy called "fab-lite". This started in 2005 when Atmel sold the MHS fab in Nantes France to Xbybus. In February 2006, Steven Laub became a director and in August president and chief executive officer. Under Laub Atmel divested more manufacturing plants and business lines. Atmel announced the sale of its North Tyneside facility (Fab9) on October 8, 2007. The manufacturing equipment was sold to Taiwan Semiconductor Manufacturing Company, Ltd. (TSMC) and the property and associated land to Highbridge Business Park Limited. In 2008, Atmel sold their fab in Germany to Tejas semiconductor. In 2010, Atmel received approval from the French government to sell its fab to Germany-based LFoundry GmbH, while retaining their design center there. Atmel completed the sale of their Secure Microcontroller Solutions smart card business to INSIDE Secure. In February 2011, Atmel sold its Digital Research in Electronics, Acoustics and Music (DREAM) business, which sold products for karaoke and other entertainment machines, for US$2.3 million. Atmel's DataFlash serial interface flash memory products were sold to Adesto Technologies in October 2012.