Schottky Ttl 1970s Develop 74ls Low Power Schottky Ttl
# Schottky TTL (early 1970s): Step 9 — Develop 74LS (Low-Power Schottky) TTL
Develop 74LS (Low-Power Schottky) TTL. The 74LS series took the same Schottky clamping technique but pointed it at a different design target: instead of pushing speed past standard TTL, 74LS raised the internal resistor values well above both standard TTL's and 74S's, cutting the current each gate drew and thus its power dissipation, while using the Schottky clamp to recover enough of the speed lost to those higher resistances that the net propagation delay came out roughly comparable to, or slightly better than, standard TTL.
## 1. 74LS: Power First
The 74LS series took the same Schottky clamping technique but pointed it at a different design target: instead of pushing speed past standard TTL, 74LS raised the internal resistor values well above both standard TTL's and 74S's, cutting the current each gate drew and thus its power dissipation, while using the Schottky clamp to recover enough of the speed lost to those higher resistances that the net propagation delay came out roughly comparable to, or slightly better than, standard TTL. The result was a family that matched standard TTL's familiar ~9-10 ns gate delay at roughly one-fifth the power per gate (around 2 mW versus 10 mW), which is the combination that made 74LS, rather than 74S, the long-term volume winner once the market had time to absorb both options.
## 2. Real Diagram: 74LS Internal Resistor Scaling vs. Standard TTL and 74S
## 3. Why Low Power Won the Long Game
74LS's power advantage compounded at the board and system level in a way that mattered more as digital systems grew: a board with several hundred TTL packages drawing one-fifth the power per gate needed a correspondingly smaller power supply, lighter-gauge power distribution, and less cooling, all of which lowered total system cost even though 74LS parts individually cost slightly more per gate than standard TTL. By the mid-to-late 1970s, 74LS had become the default choice for new general-purpose TTL designs, with standard TTL relegated to legacy designs and cost-sensitive applications where even 74LS's modest price premium mattered, and 74S reserved for the speed-critical minority of a design — the division of labor examined directly in Step 10.
## 4. Companion Diagram: Stage Sequence and Trend Summary
## Develop 74LS (Low-Power Schottky) TTL's Place in the Process Lineage
This is step 9 of 20 in the Schottky TTL (early 1970s) series, introducing the low-power-optimized 74LS family that ultimately became the dominant general-purpose TTL variant.