USING THE 4516, 4 BIT BINARY COUNTER
Home > Tutorials > 4516 4-Bit CMOS Binary Counter
Modified: 22:38, 22 October 2013
The 4516 is a 4 bit SYNCHRONOUS BINARY counter which means all the outputs change at the same time - as opposed to a RIPPLE BINARY counter whose outputs changed sequentially (albeit very quickly). It can count either up or down between 0 and 15.

Presettable:
This means when the LD input is high, then whatever binary value is present on LOAD INPUTS, will be immediately copied to the outputs and stay that way until LD goes low. This enables the counter to begin from any value. , eg count from 6 to 15. Note this only works if the RESET input is low.

Download the Datasheet for 4516
4516 IC PINOUTS
LOAD - 1
Q3 - 2
P3 - 3
P0 - 4
EN/CARRYIN - 5
Q0 - 6
CARRYOUT - 7
0V -8
16 - +V
15 - CLOCK
14 - Q2
13 - P2
12 - P1
11 - Q1
10 - UP/DN
9 - RESET

IC DESCRIPTION
Download Livewire simulation of 4516 functions
Remember to save to file, then open Livewire and navigate to the file using Open...

Take care with the priority of controls. If your circuit fails to work, chances are that you have one of the control inputs incorrectly set. For example, the counter will not count if the ENABLE is high, or will not load any presettable value if the RESET is high.

BASIC APPLICATIONS
4-BIT COUNTER

A basic 4-bit counter from 0 to 15 then resets. Each output Q0-3 will divide the CLOCK frequency by 2, 4, 8 or 16 times respectively.

Download Livewire simulation of 4-bit counter
Remember to save to file, then open Livewire and navigate to the file using Open...

DIVIDE-by-N COUNTER

This uses the LOAD (or PRESET) inputs to set the outputs to a preset binary value. The counter then counts down until zero is reached, at which point CARRYOUT goes low, is inverted by the 4069 and loads the preset value back again. In this way it will divide the input frequency by the binary value 'n' present on the LD1-4 inputs.

Download Livewire simulation of Divide-by-N counter
Remember to save to file, then open Livewire and navigate to the file using Open...

CASCADING COUNTERS

This means joining them together to make larger counters. The ENABLE is now used as a CARRYIN control.

EXPLANATION:
When the ENABLE input is high, the counter will not count and thus acts as a way of controlling the counter operation. The ENABLE also works as a CARRYIN input. This is because when the clocks are connected in parallel, the CARRYOUT goes low to enable the next digit to count on the next clock pulse. When connected sequentially (RIPPLE), the CARRYOUT connects to the clock also, returning high to on the 9 to 0 digit change, thus clocking the next digit counter. This happens at the same time the counter is disabled but it seems to work.

There are two ways of connecting SYNCHRONOUS counters.
SYNCHRONOUS
Maintains the fact that all clocks operate together, therefore all outputs change exactly the same time. Use this method if you are "trapping" and binary values or comparing bits with another output.

Note how similar controls on each IC are linked together - in parallel.

Cascading link 3 or more, the CARRYOUT's must be gated with the previous one so the next stage ENABLE only goes low when all previous counters are about to change.

Download Livewire simulation of counters
Remember to save to file, then open Livewire and navigate to the file using Open...

RIPPLE
Connected sequentially so that each counters outputs change slightly later than the previous counters. This is the cheapest and easiest method - in particular when 3 or more counters are cascaded.

Notice how the clocks are not in parallel anymore, the CARRYOUT connects to the CLOCK as well as the CARRYIN.

Cascading 3 or more is the same as for 2. The CARRYOUT connects to the clock and the CARRYIN.

Download Livewire simulation of counters
Remember to save to file, then open Livewire and navigate to the file using Open...

WHICH METHOD TO USE...

If timing and accuracy are not really important then ripple counters and connecting in RIPPLE configuration is fine. But for highly accurate timing (for trapping complex binary values) it is best done in SYNCHRONOUS. It is important that if you change direction of the counter that you do it while the clock is high - recommended by datasheet.
VOCABULARY

CASCADING - linking up counters to enable themt o count to higher values.

Presettable: - when a counter can be set to start at any value

RIPPLE - when clocks and outputs change sequentially.

SYNCHRONOUS - When all clocks and outputs of a counter change together

Trapping - To use logic gates to detect when a certain binary value is present.
Written by Phil Townshend 2010
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