4000 series
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The 4000 series is a family of industry standard integrated circuits which implement a variety of logic functions using Complementary Metal–Oxide–Semiconductor technology. They were introduced by RCA as CD4000 COS/MOS in 1968, as a lower power and more versatile alternative to the 7400 series of TTL logic chips.[1] Almost all IC manufacturers active during the era fabricated chips from this series. RCA sometimes advertised the line as COSMOS, standing for COmplementary Symmetry Metal-Oxide Semiconductor.
Initially, the 4000 series was slower than the popular 7400 TTL chips, but had the advantage of much lower power consumption, the ability to operate over a much wider range of supply voltages (3V to 15V), and simpler circuit design due to the vastly increased fanout. However their slower speed (initially only capable of about 1 MHz operation, compared with TTL's 10 MHz) limited their applications to static or slow speed designs. Later, new fabrication technology largely overcame the speed problems, while retaining backward compatibility with most circuit designs. Although all semiconductors can be damaged by electrostatic discharge, the high impedance of CMOS inputs made them more susceptible than bipolar, TTL, devices. Eventually, the advantages of CMOS (especially the later series such as 74HC) edged out the older TTL chips, but at the same time ever increasing LSI techniques edged out the modular chip approach to design. The 4000 series is still widely available, but perhaps less important than it was two decades ago.
The series was extended in the late 1970s and 1980s to include new types which implemented new or more greatly integrated functions, or were better versions of existing chips in the 4000 series. Most of these newer chips were given 45xx and 45xxx designations, but are usually still regarded by engineers as part of the 4000 series.
In the 1990s, some manufacturers (e.g. Texas Instruments) ported the 4000 series to their 74HC/74HCT series to make chips like the 74HCT4060 that offers the functionality of a 4060 IC but with the speed of the 74HCT chip.
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[edit] Design considerations
The original 4000 series was available in two versions. The A series was unbuffered, while the B series featured buffered outputs. The buffered outputs were able to source or sink more current than the unbuffered outputs, thus eliminating the need for discrete switching transistors in some designs. The buffered versions were also faster, as the signal rise time through the buffer was faster than the unbuffered chip's output transistor[2]
The 4000 series permits the use of "cookbook design" at least for slow design, where standard circuit elements can be created, shared, and connected to other circuits with few, if any, connection difficulties. This greatly speeds the design of new hardware by reusing standard approaches to circuit design. In contrast, TTL circuits, while similarly modular, often required much more careful interfacing, since the limited fanout (and fan-in) required that the loading of each output be carefully considered. Some later TTL families, like 74LS reduce this problem with fanouts of 20. It is also much easier to prototype LSI designs using the 4000 series and get repeatable and transferrable results when moving to the more integrated design.
Some care needed to be taken with the design of circuits using these chips. Many parts offered multiple gates in a single package. Using less than the complete number of gates was common, and an engineer who forgot to tie off the other gates would find the chip using too much current. The problem was caused by biasing in each gate. With the inputs disconnected, the gate would bias itself into a linear mode where the outputs were partially switched. This left the output buffer drawing a great deal of current, since it wasn't fully on or off.
[edit] Example common 4000 series chips
- 4000 - Dual 3-Input NOR Gate and Inverter
- 4001 - Quad 2-Input NOR Gate
- 4002 - Dual 4-Input NOR Gate OR Gate
- 4008 - 4-Bit Full Adder
- 4010 - hex non-inverting buffer
- 4011 - Quad 2-Input NAND Gate
[edit] Notable parts
A few parts are notable in the 4000 series because of their level of integration compared to other chips. This list is intentionally incomplete and is meant to provide a sample of the more interesting parts in the series.
[edit] 4017 decade counter
The 4017 IC is a 16-pin CMOS decade counter from the 4000 series. It takes clock pulses from the clock input, and makes one of the ten outputs come on in sequence each time a clock pulse arrives.
- Pinout
| Pin number | Name | Purpose |
|---|---|---|
| 1 | 6 | The 6th sequential output |
| 2 | 2 | The 2nd sequential output |
| 3 | 1 | The 1st sequential output |
| 4 | 3 | The 3th sequential output |
| 5 | 7 | The 7th sequential output |
| 6 | 8 | The 8th sequential output |
| 7 | 4 | The 4th sequential output |
| 8 | 0V, VDD | The connection to the 0V rail |
| 9 | 9 | The 9th sequential output |
| 10 | 5 | The 5th sequential output |
| 11 | 10 | The 10th sequential output |
| 12 | CO | Carry out output - outputs high on counts 0 to 4, outputs low on counts 5 to 9 (thus a transition from low to high occurs when counting from 9 back to 0) |
| 13 | LE | Latch enable - latches on the current output when high (i.e. the chip counts when LE is low) |
| 14 | CLK | Clock in |
| 15 | RST | Reset - sets output 1 high and outputs 2 through 10 low, when taken high |
| 16 | +9V, VCC | The connection to the +VCC rail (voltage between +3V and +15V) |
[edit] Example: Electronic Roulette
The circuit diagram on the right shows how to create a game of roulette using the 4017 decade counter and various other electronic parts. The switch stops the roulette, and the resistor adjusts the spin speed.
(Warning: Assembling this circuit requires knowledge of soldering and how to read circuit diagrams. Errors in the diagram, or made by the assembler may damage the integrated circuit).
[edit] 4026 counter and display decoder
The 4026 IC is a 16-pin CMOS seven-segment counter from the 4000 series. It counts clock pulses and returns the output in a form which can be displayed on a seven-segment display. This avoids using a binary-coded decimal to seven-segment decoder, but it can only be used to display the (decimal) digits 0-9.
- Pinout
| Pin number | Name | Purpose |
|---|---|---|
| 1 | CLK | Clock in |
| 2 | CI | Clock inhibit - when low, clock pulses increment the seven-segment |
| 3 | DE | Display enable - the chip outputs to the seven-segment when this is high (i.e. when it's low, the seven-segment is off) - useful to conserve battery life, for instance |
| 4 | DEO | Display enable out - for chaining 4026s |
| 5 | CO | Carry out output - Is high when changing from 9 to 0. It provides an output at 1/10 of the clock frequency, to drive the clock input of another 4026 to provide multi-digit counting. |
| 6 | F | Output for the seven-segment's F input |
| 7 | G | Output for the seven-segment's G input |
| 8 | VDD | The connection to the 0V rail |
| 9 | D | Output for the seven-segment's D input |
| 10 | A | Output for the seven-segment's A input |
| 11 | E | Output for the seven-segment's E input |
| 12 | B | Output for the seven-segment's B input |
| 13 | C | Output for the seven-segment's C input |
| 14 | UCS | Ungated C-segment - an output for the seven-segment's C input which isn't affected by the DE input. This output is high unless the count is 2, when it goes low. |
| 15 | RST | Reset - resets all outputs to low when taken high |
| 16 | VSS | The connection to the +9V rail |
[edit] 4511 BCD to seven-segment decoder
The 4511 IC is a 16-pin CMOS BCD to seven-segment decoder from the 4000 series. It takes the binary-coded decimal from a binary counter and decodes it to drive a seven-segment display.
- Pinout
| Pin number | Name | Purpose |
|---|---|---|
| 1 | 2s | Input for the 2s digit from the binary counter |
| 2 | 4s | Input for the 4s digit from the binary counter |
| 3 | LT | Lamp test - when low, the chip takes all the segments on the display high (to test connections, etc.) |
| 4 | BI | Blanking input - when low, the chip doesn't output to the display - to conserve battery life, for instance |
| 5 | LE | Latch enable - latches on the current output when high (i.e. the inputs change the output when LE is low) |
| 6 | 8s | Input for the 8s digit from the binary counter |
| 7 | 1s | Input for the 1s digit from the binary counter |
| 8 | 0V, VDD | The connection to the 0V rail |
| 9 | E | Output for the seven-segment's E input |
| 10 | D | Output for the seven-segment's D input |
| 11 | C | Output for the seven-segment's C input |
| 12 | B | Output for the seven-segment's B input |
| 13 | A | Output for the seven-segment's A input |
| 14 | G | Output for the seven-segment's G input |
| 15 | F | Output for the seven-segment's F input |
| 16 | +9V, VCC | The connection to the +9V rail |
[edit] See also
- List of 4000 series integrated circuits
- 7400 series
- List of 7400 series integrated circuits
- Logic gate
[edit] References
- ^ Wright, Maury. Milestones That Mattered: CMOS pioneer developed a precursor to the processor EDN, 6/22/2006
- ^ Lancaster, Don. CMOS Cookbook, ISBN 0-672-21398-2
[edit] External links
- List of 4000 series ICs manufactured by NXP Semiconductors
- Thorough list of 4000 series ICs
- [1]
