4000 series

The 4000 series (originally: CD4000 series, but now includes HEF4000 series, etc.) 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. The naming system followed the RCA convention of CA for analog, CD for digital, but did not relate to the Texas Instruments SN7400 series numbering scheme.

The CD4007 on a breadboard

Initially, the 4000 series devices could not operate at speeds as fast as 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 makes them more susceptible than bipolar transistor-based, 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 newer HCMOS technology with devices such as the 74HCT4060 providing equivalent functionality to a 4060 IC but with greater speed.

Design considerations

The original 4000 series was available in two versions: The A series was unbuffered, while the B series featured buffered inputs and outputs (in the form of additional, simple logic gates). The buffered outputs are 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 also have faster output switching times, as the signal rise time of the buffered output stage is faster than that of an unbuffered device, however the overall propagation delay through the buffered versions is higher due to the additional circuitry^[2][3]. The buffered devices are less susceptible to output oscillation with slow-changing inputs so designers have to weigh up the pros and cons of using buffered or unbuffered parts according to the nature of the circuit in which the devices are being used. The additional input and output gates on the buffered parts also make them marginally less susceptible to damage by electrostatic discharge (ESD).

Although the original designation for unbuffered and buffered parts was the addition of an 'A' or 'B' suffix to the part code (eg: 4000A = unbuffered, 4000B = buffered), some manufacturers (eg: Texas Instruments) later changed to using UB (unbuffered) and B (buffered) suffixes (eg: 4000UB and 4000B).

The diagrams below show the construction differences between a simple buffered and unbuffered CMOS NOR logic gate. Note that the logic gate at the core of the buffered part is actually a NAND gate, but the overall function of the complete circuit is a NOR gate due to the logic inversions performed by the buffers. The clamping diodes on the inputs are to offer some protection against ESD.

Buffered CMOS two input NOR gate

Unbuffered CMOS two input NOR gate

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 require much more careful interfacing, since the limited fanout (and fan-in) require 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 transferable results when moving to the more integrated design.

Some care needs to be taken with the design of circuits using CMOS chips. Many parts offer multiple logic gates in a single package and it is common to not need or use all of them. An engineer who forgets to 'tie off' (connect the unused gate inputs to VSS or VDD through pull-down or pull-up resistors may find the chip draws excessive current. The problem is caused by biasing in each gate. With the inputs disconnected, the gate will bias itself into a linear mode where the outputs are partially switched; this leaves the output buffer drawing a great deal of current since it isn't fully on or off.

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

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. Devices useful for switching analog signals (such as the 4066, and 4051 to 4053) have continued to enjoy popularity in some audio designs (although non-4000 series chips, often with less distortion, are now available).

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

Example: Electronic Roulette

Electronic Roulette circuit diagram.

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.

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

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

See also

• List of 4000 series integrated circuits
• 7400 series
• List of 7400 series integrated circuits
• Logic gate

References

External links

• List of 4000 series ICs manufactured by NXP Semiconductors
• Thorough list of 4000 series ICs
• [1]