Tie high to enable the output

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In summary: In your case, it sounds like you are working on a small PCB where tie pin 1 is connected to a 5V supply. That would mean that the output would be enabled by tying this pin to 5V. You could also tie it to a different logic signal, like GND or another 5V supply, but that would create a 'tri-state buffer' (3 states). That would be a 3-input, 3-output buffer that would be enabled when any of the inputs were tied to 5V. In summary, tie pin 1 high to enable the output.
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Enabling the output?
Hello,

I am new to engineering first year! I was wondering what "Tie pin 1 high to enable the output" My boss asked me to look at a crystal and asked me to do a small PCBA in PCB Express, but I am not sure what "high" is, is "high" tied to the +5V supply or is he asking for me to drop a pullup resistor? I would ask him again he is out on a honeymoon. Anything will help... Thanks!
 
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Welcome to PF. :smile:

Yes, "tie high" means to pull the input up to the supply rail. If the part is running off of 5V and GND, then pull that pin up to 5V. You can tie it directly to 5V with a trace, but a better practice is to pull it up through a medium-size resistor (10k-40k-ish). That allows testing of the enable/disable function in manufacturing, at the cost of one resistor. Your Manufacturing Engineering Department may have "Design for Manufacturability Rules" that will dictate whether you tie directly with a trace or through a resistor.

Always check the part's datasheet to be sure you understand the allowed supply voltages, input current specs, etc. Have fun learning!
 
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It means to connect that pin to the high supply, which it sounds like is +5V in your case. It probably doesn't matter whether you connect it to the high supply directly (with a wire), or whether you connect it through a resistor. Do you have the datasheet for the component you are working with? It might have some info. The chip is probably designed so that you have to connect this pin to the high supply in order for the outputs to drive out data, this is what "to enable the output" means. This is often called 'Output enable", and an output using this is called a "tri-state buffer". See this link for example:
https://www.electronics-tutorials.ws/logic/logic_9.html
 
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(Great minds think alike) :wink:
 
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Interesting! Makes sense. since this is my first board spin I am anxious to get his done! Thanks for your assistance!
 
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New Kid said:
"Tie pin 1 high to enable the output"
That statement refers an input logic signal that needs to be connected to a high = positive logical 1, to enable the outputs. That could be a positive supply, or it could be to some other logic signal that remains high = 1.
 

1. What does it mean to "tie high" in relation to enabling an output?

Tying high refers to connecting a signal or input to a high voltage level, typically the highest voltage level in the system. In this case, tying high is used to enable the output, meaning it allows the output to be activated or turned on.

2. Why is it important to tie high when enabling an output?

Tying high is important because it ensures that the output is only enabled when the desired conditions are met. This helps prevent any accidental or unintended activation of the output, which can cause malfunctions or damage to the system.

3. How is "tie high" achieved in a circuit or system?

"Tie high" can be achieved by connecting the signal or input to a high voltage source, such as the positive supply voltage. This can be done using a resistor or a switch, depending on the specific circuit design.

4. Can "tie high" be used to enable multiple outputs at the same time?

Yes, "tie high" can be used to enable multiple outputs simultaneously. This can be achieved by connecting all the signals or inputs to the high voltage source, or by using a logic gate to combine the signals and then tying the output of the gate to the high voltage source.

5. Are there any potential drawbacks to tying high to enable an output?

One potential drawback is that tying high can consume more power, as the signal or input is constantly connected to a high voltage source. This can also lead to increased heat dissipation, which may need to be managed in the system design. Additionally, if the high voltage source fails, it can cause the output to be unintentionally enabled or disabled.

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