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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It’s datashedt a 3-state output. So this makes up 12 of the 14 pins of the chip. The 74HC chip is a quad tri-state buffer 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.

So a tri-state buffer is just like a logic chip in that it offers HIGH or LOW states, but it also offers the additional state of high impedance.

This logic is shown in 74hf125 table below. And Z stands for “high impedance”. This establishes power to the 74HC Pin 1 is the output enable pin, labeled C on the pinout. 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.

74HC125 Datasheet

So when the pushbutton is unpressed, the 2 inputs are in LOW logic state. If it is HIGH, the output will be in a high impedance state. If we don’t press down on the pushbutton attached to pin 1, the buffer will be in a high impedance state. If we do this to all the tri-state buffers save one, the bus can listen to one device at any given time. When the output enable pin is LOW, this pin determines the logic state of the output.


So in order for the LED to turn on, this button must be pressed. It is an active LOW pin. The 74HC is a pin chip. The pinout for the 74HC is shown below. Tri-state Buffer Logic 3-state Logic. The output enable pin enables output. Pin 2 is the data input pin, labeled A on the pinout.

Each tri-state buffer has 3 pins associated with them- 2 input pins and 1 output pin. If this button is not pressed, it does not matter whether we press the input button or not. And this is how a tri-state buffer circuit can work with a 74HC chip.

This pin is active LOW. Each tri-state buffer of the 74HC has 2 inputs, an output enable and the data input. To this pin, we connect the output device; in 74h125 case, it’s an LED.

When we press down on the pushbuttons, the logic state of the pins is now HIGH. It is labeled C on the inputs of the tri-state buffers.

74HC Datasheet(PDF) – Diodes Incorporated

One terminal is connected to 5V and the other to ground. This essentially cuts it off the output from the bus it is connected to. We connect the 2 inputs of the tri-state buffer to pull-down resistors. In this circuit, we will simply connect a tri-state buffer and show how it works with manual pushbutton control.


Pin 3 is the output pin. A tri-state buffer is a buffer that can be in 1 of 3 output states. They’re also used in registers and flip flops, datsheet they appear a lot in computer memory 74hc152 processors.

For this circuit, we’re just using a single tri-state buffer. If the output enable is disabled, the input pin has no effect.

Datasheeet it’s as if it is not connected at all. So this is why tri-state buffers work really good with their 3-state logic. 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.

The datasheet for the 74HC is shown at the following link: How the Circuit Works How the circuit works is only both pushbuttons are pressed down does the output, which is the LED, turn on.