SN54/74LS • SN54/74LS • SN54/74LS DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified). S. b l. P. 74LS Octal Buffers AND LINE Drivers WITH 3-state Outputs SN74S, SN74S OCTAL BUFFERS Details, datasheet, quote on part number: 74LS Texas Instruments 74LS Buffers & Line Drivers are available at Mouser Electronics. Mouser offers inventory, pricing, & datasheets for Texas Instruments .

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Please show the schematic diagram. A tristrate output can have 3 different states: Pull pin 19 high, and the output will follow the input 17 and either the green or the red LED will glow brightly; the other one datasheet be off. If you use a 5V power supply, and make sure this is always connected to the 74ld241 Vcc and Gnd pins see belowthen you should see expected behaviour.

Do you understand WHY we have tri-state outputs?

(PDF) 74LS241 Datasheet download

From what I read, if two input are high on a buffer, then the output will be high. I don’t know that I’d actually seen a chip manufacturer document the behavior, but I’ve observed it and understood enough about silicon to understand that two P regions joined by an N region form a transistor.

Which I have interpreted as: Do you understand what a buffer is and why we use it? Although it is not “best practice” to do this, datasheeg LS TTL inputs will usually float high, as PeterBennet has already kindly explained.

I’m trying to understand how the 74LS works. I have put a led on the 3 output pin, in order to test the output. Why is my microcontroller passing daatsheet current through it when not connected? Mr Bonjour 1 2 Which I have interpreted as being: But I thought gate like those didn’t need to be protected.


A 74LS or any 74LS family part will datasueet see an unconnected input as a High – you need to connect inputs directly to Ground to input a Low.

Post Datashet 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. I don’t use the two G inputs at the same time. Sign up using Email and Password.

I have the feeling that I have understood the schematic, but the fact is this is not working. And when I connect the Vcc pin, without 19 and 17, my led is on, where I expected this to be off. It is likely that the output remained in a high-impedance state, so the LED did not light. Sign up or log in Sign up using Google. Note that you may not enable both G inputs e.

Note the invertor symbol tiny o ring at the control gate connected to pin 1; you must pull pin 19 high to activate, and pin 1 low to activate. SE topics where powering devices via other pins, instead of the power pins, caused unexpected behaviour:.


And we still don’t know how you have your LED connected???? I have tried other gate 19 with 15, 13, 11 and I have the same behavior. The LED being lit is not a surprise. JvO 2 Home Questions Tags Users 74le241.


74LS datasheet, Pinout ,application circuits OCTAL BUFFERS AND LINE DRIVERS WITH 3-STATE OUTPUTS

I was wondering if I didn’t have broke my chip because I don’t have protected the input gate, but it wasn’t asked in the schema. So I clearly don’t understand at all. These ‘G’ inputs must be activated in order to have the buffers connected to them pull their outputs low or high, depeding on their input. So here is what I did: In the first two instances the output is actively pulled low or high using a transistor; in the disconnected state, neither transistor is activated.

This is clearly what I am daatasheet. I’ve done quite a dwtasheet of research since first writing this answer, and datasehet unpowered 74LS devices and an input voltage between 0 V datasneet 5. Unless you know exactly what you are doing and its consequences, do not apply voltages to the other pins dahasheet an IC, without the correct power supply voltage s also being supplied to its specified power pins i.

I was expecting that my led will be off with pin 17 not connected but pin 19 still high, and the led on with 17 and 19 high, but this is not happening. This circuit will help: Another issue I’ve observed is parts that behave as though pairs of pins are connected via PNP transistor, such that excessive voltage on one will cause the device to source current into the adjacent pin.