Prefix	Indicates the manufacturer (though is not definitive)
	e.g. SN indicates Texas Instruments
Temp Range	Denotes the temperature range
	e.g. 74 indicates a commercial temperature range (54 indicates a MILitary temp range)
Chip Type	Indicates the type of logic circuits used*
	e.g. LS indicates Low Power Schottky (lower power, high speed) - most MTX chips are LS*
Device Type	Indicates the type of device
	e.g. 123 describes a Dual Retriggerable Monostable Multivibrator
Suffixes	Often manufacturer specific, denoting package type, quality, etc.
	e.g. N for Texas Instruments, specifies a Plastic DIL package
Putting it all together . .  . . SN74LS123N

 

^* TTL ICs on Memotech PCBs

As noted in the table, the majority of TTL ICs on Memotech PCBs are 74LS, Low Power Schottky. In a few instances, for example on the FDX 80 Column Board, there are a mixture of 74LS and 74S. The S versions of the 74 series are faster than the LS versions, but have a higher power consumption. The 74LS has a typical gate delay of 10ns with a power dissipation of 2mW, whereas the S version has a typical gate delay of 3ns with a power dissipation of 20mW.

Components with a "74F" prefix are manufactured by Fairchild Semiconductor, they are faster then the TI 74LS equivalents, with gate delays of 3.5ns compared to 10ns for a 74LS and are used in circuits requiring high speed operation, such as the Video Wall Distributed Digital Frame Store controller board. The power consumption of the 74F is much reduced when compared with the 74S, offering a speed compatible with the 74S with power dissipation comparable to the 74LS.

Back to Datasheets