Octal Transceiver with 3-State Output. Features. Packaging: DIP; CMOS Technology; Voltage: 5V; 74HCT Series. Report a problem · Suggest a product. The 74HCT is identical in pinout to LS The device has. TTL-Compatible Inputs. The HCT is a 3-state noninverting transceiver that is used for. 3 Description. The SNx4HCT octal bus transceivers are designed for asynchronous two-way communication between data buses. The control-function .

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But the detection circuit is a ticking time bomb, ready to go off and cause incorrect behavior.

Last edited by TechAlex; at Even the ones which emulate DMX protocol are unidirectional. I only need 2 channels Especially the mosfet plus 74ct245 circuit in of limited use, mainly only for I2C, and nearly useless for high speed communication! Those passive level converters, using a N-channel mosfet and 2 resistors, are really only good to use for I2C.

I know they aren’t the same exact thing, but I would like to understand how they differ and are they interchangeable in regards to communicating with led strips from a teensy?

I have a few of the 74HCT’s 74uct245 the way.

74HCT245 – Octal Bus Transceiver, 3 State, TTL Logic Level

Originally Posted by visualSound. A unidirectional buffer or able to buffer with way, but hard-wired for the intended direction is the right way to buffer WS data signals. I’m still getting up to speed on making sense of schematic’s and data sheets, so I’m having trouble understanding the difference between these two chips.

The TXS shifter appears to work for just a few leds, though there was one failure with a so-called grumpy strip. I am using the CD74HCTE to drive 12x5m of 12v ws strips over 30 feet of cheap thermostat cable and it 74hc2t45 great.


74HCT buffer IC – Electrical Engineering Stack Exchange

Thereafter, the output voltage is maintained with only a weak 74hcy245. The momentary strong drive solves the slow low-to-high transition. Yeah I saw this post a few days ago, I was curious if it was as simple as one just not being compatible.

It’s slightly smaller and maybe slightly less expensive, but still pretty similar. Why would an AND gate not function as a level shifter? Wow, thanks for the break down Paul, Yeah I will be investing in 74hcg245 of those adapters for the next project, right now I’m kind of keeping things small and getting educated on all this stuff as it’s my first time playing with these led strips.

What is the difference between the 74HCT and sparkfun’s logic level converter?

Also note – if you are running over very long distances you need to account for voltage drop. Thanks for the confirmation!

That’s super helpful, thank you for explaining. Seems like it is! Both chips have the same TTL level logic input circuit a specific ratio of mosfet sizes: When driving long wires to LED strips, where huge changes in current also happen along shared ground paths, those drivers can easily become a liability. All times are GMT. Last edited by Michael Ward; at Low voltage presents a lot like a degraded signal – so check!

The two shifters from Sparkfun just cannot handle the kHz signals that WS lights generate: Whatever you do, don’t believe the maker myth that you can buy a cheap bidirectional level shifter as a universal solution to all 3 vs 5 volt interfacing needs. For a large LED project, I highly recommend you follow the wiring advice on that page, especially locating the power supplies as close as practical to the LEDs and use short, large diameter wires for the LED power.


This little chip solved a problem I have been having for some time.

It also has the ohm series line matching resistors, and RJ jacks to plug in CAT6 cable which exactly matches the ohm resistors and offers excellent signal quality. And could something like an ULN also work? Originally Posted by PaulStoffregen.

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It really is the right approach. Even though the ‘ is depicted as a pair of buffers, inside the chip is it certainly implemented as several logic gates based on the 3 input signals which create 2 internal logic signals that drive the 2 big mosfet transistors connected to the output pin.

Even just connecting extra wire to the output, especially when experimenting on a breadboard, can really alter the low-to-high speed. Results 1 to 22 of What is the difference between the 74HCT and sparkfun’s logic level converter? Their big weakness is the high level output on either side is only due to the weak pullup resistor, so the low-to-high output is very slow.

Those TXB chips work similarly to the passive approach, except a circuit detects any unexpected change at the “output” and very briefly drives the other side high very strongly for 74hcg245 brief 47hct245.