Thursday, 31 August 2017

TTL - Index and notes

There seem to be three common families of ICs that I regularly come across when building synths.
1. CMOS (digital)
2. Linear (mainly analog)
3. TTL (Digital)

Linear ICs are solid-state analog devices characterized by a theoretically infinite number of possible operating states. They operate over a continuous range of input levels. In contrast, digital ICs have a finite number of discrete input and output states.

I've already started a page on CMOS. You can see it here.
(I'll do a Linear page later)
TTL and CMOS contain digital devices such as logic gates, flip flops, counters, decoders, etc.
Linear ICs are mostly analog and you will see them in amps, oscillators, regulators, etc etc
TTL stands for Transistor-Transistor Logic. They are built from bipolar junction transistors and resistors.
The ICs are mostly 4 or 5 digits and usually start with a 74 or 54. (eg: 7400 or 5404).
They are less sensitive to static electricity (unlike CMOS),
 but have a narrow operational voltage range (5 to 5.25V).
Inputs should always go somewhere. That is not be left floating.

TTL ICs use much more current that CMOS but are faster.
TTL have a low input impedance in comparison to CMOS .

Common ICs
7400 - quad 2 input NAND  eg74HC00
7402 - quad 2 input NOR gate
7404 - Hex inverter
7408 - quad 2 input AND eg:74HC08
7410 - triple 3 input NAND
7411 - triple 3 input AND
7420 - dual 4-input NAND
7421 - Dual 4-input AND
7427 - triple 3 input NOR
7432 - quad 2-input OR
744002 - dual 4-input NOR
744075 - triple 3-input OR
747266 - quad 2-input XNOR
7486 - quad 2-input XOR


The history and identification of the TTL chip family
TTL was invented in 1961 by James L. Buie. The first commercial integrated-circuit TTL devices were manufactured by Sylvania in 1963. TTL became popular with electronic systems designers after Texas Instruments introduced the 5400 series of ICs, in 1964 and the later 7400 series in 1966.
The Texas Instruments 7400 family became an industry standard. Compatible parts were made by Motorola, AMD, Fairchild, Intel,and many other manufacturers around the world.

* 74xx - old original chips. Now obsolete
* 74Sxx - Higher speed Schottky. (1969). Also obsolete
* 74LSxx - Low power Schottky
* 74ASxx - Advanced Schottky (1985) 
* 74HCxx - High speed using CMOS circuitry
* 74HCT - High speed,low power using  CMOS circuitry. The devices are pin compatible with             existing devices such as the 74TTL, 74STTL,  4000 series and the 74LS family.
 * 74xx - that have other letters after the 74. These are usually modern, fast surface mount

TTL devices are usually packaged in dual in-line packages (DIPs), usually with 14 to 24 pins.
Today, many TTL-compatible devices are available in surface-mount packages, which are available in a wider array of types than through-hole packages.

Most manufacturers offer commercial and extended temperature ranges: for example Texas Instruments 7400 series parts are rated from 0 to 70 °C, and 5400 series devices over the military-specification temperature range of −55 to +125 °C.

Links
+ Ken Stone Digitally controlled oscillator
+ List of 7400 series ICs
+Transistor-Transistor Logic

 Please let me know if there are any mistakes or omissions.

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