MOS technology. They have the same high speed performance of. LSTTL combined with true CMOS low power con- sumption. These devices require the same. 74HC Datasheet, 74HC Quad Bus Buffer Datasheet, buy 74HC 74HC datasheet, 74HC pdf, 74HC data sheet, datasheet, data sheet, pdf, Diodes, QUADRUPLE 3-STATE BUFFERS OE LOW.

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datazheet So this is why tri-state buffers work really good with their 3-state logic. How the Circuit Works How the circuit works is only both pushbuttons are pressed down does the output, which is the LED, turn on. If it is HIGH, the output will be in a high impedance state.

dstasheet If the output enable is disabled, the input pin has no effect. Pin 1 is the output enable pin, labeled C on the pinout.

74HC125 Datasheet

This logic is shown in the table below. Each tri-state buffer of the 74HC has 2 inputs, an output enable and the data input. This essentially cuts it off the output from the bus it is connected to. It is an active LOW pin. The 74HC chip has 4 independent tri-state buffers. When the tri-state buffer is in a high impedance state, the output of a tri-state buffer is removed from the line that it is connected to.


One place to find is at Tayda Electronics at the following link: The output enable pin enables output.

74HC Datasheet PDF –

And Z stands for “high impedance”. We connect the 2 inputs of the tri-state buffer to pull-down resistors. Pin 3 is the output pin.

Only if these conditions are met does the output go HIGH. So it’s as if it is not connected at all.

How to Build a Tri-state Buffer Circuit with a 74HC125 Chip

If we don’t press down on the pushbutton attached to pin 1, the buffer will be in a high impedance state. And this is how a tri-state buffer circuit can work with a 74HC chip. With the output enable still enabled, if we push down on the input pushbutton, the output will be in a HIGH logic state.

The pinout for the 74HC is shown below. So when the pushbutton is unpressed, the 2 inputs are in LOW logic state. The tri-state buffer isn’t used for a real-life purpose as it would be done; this circuit simply just shows how it works. This means it contains 4 independent tri-state buffers. If the output enable is disabled, this puts the buffer in a high-impedance state. This pin is active LOW. The input, labeled A, determines the output. So in order for the LED to turn on, this button must be pressed.


The datasheet for the 74HC is shown at the following link: The 74HC chip is a quad tri-state buffer chip.

How to Build a Tri-state Buffer Circuit with a 74HC Chip

Each tri-state buffer has 3 pins associated with them- 2 input pins and 1 output pin. So this makes up 12 of the 14 pins of the chip. Now if we press down on the output enable pushbutton, enabling the output, and we don’t press down on the input pushbutton, the output will be in a LOW logic state.

In this project, we will build a tri-state buffer circuit with a 74HC chip. If this button is not pressed, it does not matter whether we press the input button or not. Tri-state Buffer Logic 3-state Logic.