Each circuit functions as a 4-input NAND gate, but because of the Schmitt action, it has different input threshold levels for positive (VT+) and for negative going (VT-) signals.
These circuits are temperature-compensated and can be triggered from the slowest of input ramps and still give clean, litter-free output signals.
The SN5413 and SN54LS13 are characterized for operation over the full military temperature range of -55°C to 125°C. The SN7413 and SN74LS13 are characterized for operation from 0°C to 70°C.
Manufactured: 1974 week 17