What is unique about TTL devices such as the 74SXX?

• These devices use Schottky transistors and diodes to prevent them from going into saturation; this results in faster turn-on and turn-off times, which translates into higher frequency operation.
• The gate transistors are silicon (S), and the gates therefore have lower values of leakage current.
• The S denotes the fact that a single gate is present in the IC rather than the usual package of 2–6 gates.
• The S denotes a slow version of the device, which is a consequence of its higher power rating.