USING THE 4516, 4 BIT BINARY COUNTER 

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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: 
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 
4BIT COUNTER
A basic 4bit counter from 0 to 15 then resets. Each output Q03 will divide the CLOCK frequency by 2, 4, 8 or 16 times respectively.

DIVIDEbyN 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 LD14 inputs.


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

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.

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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