74LS08 PDF

SN54/74LS QUAD 2-INPUT AND GATE. LOW POWER SCHOTTKY. J SUFFIX . CERAMIC. CASE N SUFFIX. PLASTIC. CASE 1. 1. Symbol. Parameter. DM54LS DM74LS Units. Min. Nom. Max. Min. Nom. Max. VCC. Supply Voltage. 5. 5. V. VIH. High Level Input. Note The ”Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaran- teed The device should not be operated at.

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74LS08 – Quadruple Two Input AND Gate

Top menu About Us Contact. As you can see the LED is on by default despite neither button being pressed. Pull down resistors as suggested in another answermight also a good idea.

Both transistors will be ON and voltage across both of them will be zero. If you do use a pull down resistor, make it low like PeterBennett recommended. This LED is connected to detect the state of output. When any one of the buttons is pressed.

74os08 am new to electrical engineering still so forgive me if I am making a stupid mistake. Next Article Timer IC. And after a google search I havnt come up with anything, usually the videos are terrible quality or they are using a different AND gate. Output of the AND gate is the voltage across resistor R1.

74lz08 realizing the above truth table let us take a simple AND gate application circuit as shown below. Then if your IC is good your switches are mis-wired, I have done it myself with that type of switch. The chip is basically used where AND logic operation is needed.


If you want to absolutely avoid learning the pin out of these push buttons, always connect them in diagonal. Sign up using Facebook. Skip to 47ls08 content. Pressing the buttons does nothing.

74LS08 Datasheet

Many pins left floating. For better understanding the internal working let us consider the simplified internal circuit of AND gate as shown below. With the LS you need to sink 1. Home Questions Tags Users Unanswered. The chip is available in different packages and is chosen depending on requirement. It might be oscillating as well.

At this time the total VCC appears across resistor R1. There are four legs connected together in pair of two. It is really popular and is available everywhere. The inputs of the 74LS family and other TTL versions source significant current and will appear as a logic High unless firmly pulled to Ground – your k resistors won’t help. Sign up using Email and Password. By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies.

They are notorious for that particular mishap.

74lx08 inputs on CMOS parts anything with a “C” in the middle source or sink very little current, so K pull-up or -down will work with them. Simon Marcoux 1, 2 When both buttons are not pressed. If you choose the wrong pair, you end up with an always on switch.


The inputs with both switches unpressed allow the pins to float around, depending on the way the IC is set-up internally. In that case, the left button should have a red wire on the lower left pin. The chip is used in systems where high speed AND operation is needed. In this state the current flow through base of both transistors will be zero. You might be using push buttons that are connected 47ls08 such a way that the legs are shorted connected together.

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There are four AND gates in the chip, we can use one or all gates simultaneously. 74l0s8 two inputs of AND gate are driven 7l4s08 from bases 74lss08 the two transistors.

When both buttons are pressed. Post Your Answer Discard By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies.