TTL and CMOS differ in voltage levels, speed and power.
TTL (5 V bipolar) and CMOS (wide supply, low static power) families have defined thresholds V_IL, V_IH, V_OL, V_OH and noise margins. Modern families: LVCMOS at 3.3, 1.8 V. Level shifters interface different families. Open-drain outputs allow wired-AND.
A 3.3 V sensor output into a 5 V input may need a level shifter.
Logic family determines voltage levels, speed and power, so you must match them when connecting devices from different sources.
TTL and CMOS differ in voltage levels, speed and power.
Logic family determines voltage levels, speed and power, so you must match them when connecting devices from different sources.
The difference between the output level a device guarantees and the input level it requires, which tells you how much noise the link can tolerate.
Driving a 3.3 V input from a 5 V output can exceed its absolute maximum rating, so a level shifter or divider is needed.
Typical applications include interfacing a 3.3 V microcontroller with a 5 V sensor, choosing CMOS logic for a battery device to save power and checking the noise margin of a legacy TTL circuit before replacing it.
Study "Memory types" first (topic 47 of 104 in Electronics & Embedded). It covers the groundwork this topic builds on.
Fan-out. Speed-power trade-off. Unused inputs must be tied.
A 3.3 V sensor output into a 5 V input may need a level shifter.
The next topic is "ADC", which builds directly on this one.
It is classed as Intermediate in Electronics & Embedded (topic 48 of 104). It is an intermediate topic. Work through the beginner topics in Electronics & Embedded first.
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