Glue Logic
Logic Speed x Power Chart

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Speed vs Power Chart

This is a graph of Glue Logic speed [in nS] vs. Quiescent power consumption [in mW]. The switching speed is constant as defined in the graph, but the power consumption will change as the device switches. Quiescent means the device is in a steady state, at rest or not being used. While the device is stopped the graph holds true for power consumption, but as the device starts to operate the current increases. So as the switching speed increases many of the CMOS logic family devices will approach the TTL logic family devices for power consumption. It only holds when the devices are not operating! CMOS logic families consume little power because their output pin resides between one NMOS FET and one PMOS FET, so normally only one FET is conducting. How ever as the device begins to switch both FETs begin to conduct increasing the current consumption of the device. As the CMOS current consumption increases it begins to approach the consumption of TTL devices. Seems like I saw by 50Khz the CMOS and TTL families consumed the same power, may have been 500KHz. In either case the slope of the consumption curve is different, as the TTL devices increase their current consumption faster then the CMOS devices. But by 50KHz they both level out at about the same current demand. The ECL [Emitter Coupled Logic] devices consume the same current regardless of the switching speed.
The X axis represents Quiescent power consumption (mW), the lower the number the less power used. The graph shows the glue logic families with no input signal applied. When switching, CMOS and TTL dissipate near the same power.
The Y axis represents propagation delay in 'nS' [10-9 seconds], the lower the number the faster the device.

This is a guide, the numbers change with each different company. I believe that I picked an average number to represent the family. Complied back in 1995, I think I used Propagation delay numbers for AND gates (which are normally available in all families). All TTL, CMOS, mixed TTL/CMOS and ECL Glue Logic families are listed [as of 1995]. So based on this graph the best Glue Logic IC family to use would be ACTQ; Advanced CMOS with TTL input logic switching levels, with non-spike-ing outputs [slow output switching levels]. There are a number of bus driver families which are not listed above. Bus driver families normally only contain 'bus' drivers and receivers.




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Electronic Design Key words: Glue Logic Families, Operating Speed, CMOS, TTL, ECL, Speed, Speed-Power Product, IC, Integrated Circuits, Propagation delay, Device Quiescent power consumption, 74xx, Speed vs. Power, Logic family listing, Logic family types, Definition for Logic family, Logic Terms, TTL: Transistor Transistor Logic, ECL: Emitter Coupled Logic, CMOS: Complementary Metal-Oxide Semiconductor, BICMOS: Bipolar Complementary Metal Oxide Semiconductor

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Last Modified: 2/26/08
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