4093 Quad 2-Input NAND Schmitt Trigger

The 4093 is a CMOS chip with four NAND gates with a Schmitt trigger. Because each gate has two inputs and has four gates inside, it’s often referred to as a Quad 2-Input NAND Schmitt Trigger.

A NAND gate with a Schmitt trigger works more or less like a normal NAND gate. With the exception that the threshold for when it switches from LOW to HIGH is different from when it switches from HIGH to LOW.