▁voltage ▁reg ulator ▁integrated ▁circ uits . ▁The ▁ 7 8 xx ▁family ▁is ▁commonly ▁used ▁in ▁electronic ▁circ uits ▁requiring ▁a ▁reg ulated ▁power ▁supply ▁due ▁to ▁their ▁ease - of - use ▁and ▁low ▁cost . ▁ ▁N omen cl ature ▁and ▁pack aging ▁For ▁IC s ▁within ▁the ▁ 7 8 xx ▁family , ▁the ▁xx ▁is ▁replaced ▁with ▁two ▁digits , ▁indicating ▁the ▁output ▁voltage ▁( for ▁example , ▁the ▁ 7 8 0 5 ▁has ▁a ▁ 5 - vol t ▁output , ▁while ▁the ▁ 7 8 1 2 ▁produces ▁ 1 2   vol ts ). ▁The ▁ 7 8 xx ▁line ▁are ▁positive ▁voltage ▁regul ators : ▁they ▁produce ▁a ▁voltage ▁that ▁is ▁positive ▁relative ▁to ▁a ▁common ▁ground . ▁There ▁is ▁a ▁related ▁line ▁of ▁ 7 9 xx ▁devices ▁which ▁are ▁complement ary ▁negative ▁voltage ▁regul ators . ▁ 7 8 xx ▁and ▁ 7 9 xx ▁IC s ▁can ▁be ▁used ▁in ▁combination ▁to ▁provide ▁positive ▁and ▁negative ▁supply ▁volt ages ▁in ▁the ▁same ▁circuit . ▁▁ 7 8 xx ▁IC s ▁have ▁three ▁terminal s ▁and ▁are ▁commonly ▁found ▁in ▁the ▁TO - 2 2 0 ▁form ▁factor , ▁although ▁they ▁are ▁available ▁in ▁surface - mount , ▁TO - 9 2 , ▁and ▁TO - 3 ▁packages . ▁These ▁devices ▁support ▁an ▁input ▁voltage ▁anywhere ▁from ▁around ▁ 2 . 5 ▁vol ts ▁over ▁the ▁intended ▁output ▁voltage ▁up ▁to ▁a ▁maximum ▁of ▁ 3 5 ▁to ▁ 4 0