Na família TTL temos:

74/54 TTL standard

74/54 TTL low power

74H/54H TTL High speed

74S/54S TTL sehotthy

74LS/54LS TTL Low - Power Schttkey

74SLS/54ALS TTL Adeanced Low -Power Shottky

74AS/54AS TTL Adeanced Shottky 

Exemplo de uma TTL