In 1972, Signetics originally released the 555 timer in 8-pin DIP and 8-pin TO-5 metal can packages, and the 556 timer was released in 14-pin DIP package [REF].
Currently, the 555 is available in through-hole packages as DIP-8 and SIP-8 (both 2.54mm pitch),[REF] and surface-mount packages as SO-8 (1.27mm pitch), SSOP-8 / TSSOP-8 / VSSOP-8 (0.65mm pitch), BGA (0.5mm pitch) [REF].