AVR531: Migrating from ATtiny261/461/861 to ATtiny261A/461A/861A 8-bit Microcontrollers 1 Introduction Application Note In order to optimize the manufacturing process and to further reduce current consumption, an optimized version of ATtiny261/461/861 has been introduced. The ATtiny261A/461A/861A is a functionally identical, drop-in replacement for the ATtiny261/461/861. All devices are subject to the same qualification process and same set of production tests, but as the manufacturing process is not the same some electrical characteristics differ. ATtiny261/461/861 and ATtiny261A/461A/861A have separate datasheets. This application note outlines the differences between the two devices and the datasheets. There is also a detailed change log to assist the user at the end of the ATtiny261A/461A/861A datasheet. Remember to always use the latest revision of the device datasheet. Minor differences in typical characteristics are not discussed in this document as long as the low and high limits remain the same. For detailed information about the typical characteristics, see sections “Electrical Characteristics” and “Typical Characteristics” of the device datasheets. Note: This application note serves as a guide to ease migration. For complete device details, always refer to the most recent version of the ATtiny261A/461A/861A data sheet. Rev. 8245A-AVR-10/09 2 Changes in Characteristics This section outlines such differences in characteristics that may have an effect on the application in which the device is used. For detailed information, refer to the most recent version of the device data sheets. 2.1 Current Consumption Active and Idle mode current consumption of the device have been reduced. The table below present typical current consumption figures at room temperature. All values are taken from device datasheets. Table 2-1. Typical Current Consumption of Device at Room Temperature Mode Active Idle Condition ATtiny261/461/861 ATtiny261A/461A/861A Change VCC = 2V, f = 1 MHz 400 µA 200 µA -50 % VCC = 3V, f = 4 MHz 2 mA 1.2 mA -40 % VCC = 5V, f = 8 MHz 6 mA 3.6 mA -40 % VCC = 2V, f = 1 MHz 100 µA 35 µA -65 % VCC = 3V, f = 4 MHz 400 µA 250 µA -40 % VCC = 5V, f = 8 MHz 1.5 mA 0.9 mA -40 % 2.2 Reset The table below summarizes the differences between the reset circuitry of ATtiny261/461/861 and that of ATtiny261A/461A/861A. Table 2-2. Changes in Power-On Reset ATtiny261/461/861 Symbol ATtiny261A/461A/861A Unit Min Typ Max Min Typ Max VPOR 0.7 1.0 1.4 1.1 1.4 1.6 V VPOA 0.05 0.9 1.3 0.6 1.3 1.6 V SRON 0.01 - 4.5 0.01 - - V/ms 3 New or Updated Bits and Registers The following table illustrates bits that have changed since ATtiny261/461/861. Some bits were marked as reserved in ATtiny261/461/861 and some bits have another use in ATtiny261A/461A/861A. Table 3-1. New or Updated Bits and Registers in ATtiny261A/461A/861A Addr. Name Bit 7 0x35 MCUCR BODS 0x31 Notes: 2 OSCCAL CAL7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 BODSE (1) 1. ATtiny261/461/861 was equipped with two, overlapping frequency ranges while ATtiny261A/461A/861A has one, continuous frequency range AVR531 8245A-AVR-10/09 AVR531 4 Datasheet Changes For a summary of changes, see the revision history at the end of the ATtiny261A/461A/861A data sheet. 3 8245A-AVR-10/09 Disclaimer Headquarters International Atmel Corporation 2325 Orchard Parkway San Jose, CA 95131 USA Tel: 1(408) 441-0311 Fax: 1(408) 487-2600 Atmel Asia Unit 1-5 & 16, 19/F BEA Tower, Millennium City 5 418 Kwun Tong Road Kwun Tong, Kowloon Hong Kong Tel: (852) 2245-6100 Fax: (852) 2722-1369 Atmel Europe Le Krebs 8, Rue Jean-Pierre Timbaud BP 309 78054 Saint-Quentin-enYvelines Cedex France Tel: (33) 1-30-60-70-00 Fax: (33) 1-30-60-71-11 Atmel Japan 9F, Tonetsu Shinkawa Bldg. 1-24-8 Shinkawa Chuo-ku, Tokyo 104-0033 Japan Tel: (81) 3-3523-3551 Fax: (81) 3-3523-7581 Technical Support [email protected] Sales Contact www.atmel.com/contacts Product Contact Web Site www.atmel.com Literature Request www.atmel.com/literature Disclaimer: The information in this document is provided in connection with Atmel products. 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