The ATtiny13a microcontoller family

The ATtiny13A is an Atmel (now Microchip) part with the 8 bit AVR risc instruction set. It is part of the following family:

13A - 1K flash, 64 bytes SRAM, 64 bytes EEPROM
25  - 2K flash, 128 bytes SRAM, 128 bytes EEPROM
45  - 4K flash, 256 bytes SRAM, 256 bytes EEPROM
85  - 8K flash, 512 bytes SRAM, 512 bytes EEPROM

In my case I am thinking of "upgrading" a flashlight design based on the ATtiny13A. Some extra space in flash might allow fancy features (or just be needless overkill). Whatever the case, several issues need to be considered.

One is package type. My flashlight uses the Attiny13a-SSU part, which is an 0.150 inch wide surace mount package (S8S1 package). Not all of the other chips are available in this narrow package! The ATtiny85 is only available in the "8S2" package, which is 0.208 inches wide.

The other consideration is power supply voltage and processor speed. In the case of the "85" chip you have two basic choices. The "V" part (ATtiny85V-10SU) has a maximum 10 Mhz clock and runs on lower voltages (1.8 – 5.5 volts). The regular part (ATtiny85-20SU) has a maximum 20 Mhz clock, but requires higher voltage (2.7 – 5.5). For a flashlight running from a single Li-ion cell, either would seem to be suitable (at 3.2 volts a Li-ion cell is fully discharged, and some lights will not even allow a discharge this low).