Hex Non-Inverting Buffers. Datasheet ( KB) without level translation. The ‘ HC and ‘HC are enhanced versions of equivalent CMOS types. Symbol. Parameter. Value. Unit. VCC. Supply Voltage. to +7. V. VI. DC Input Voltage. to V. VO. DC Output Voltage. to VCC + V. IIK. DC Input. M54HCF1R datasheet, M54HCF1R pdf, M54HCF1R data sheet, datasheet, data sheet, pdf, SGS Thomson Microelectronics, HC HEX.

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Level shifting with the 74hc chip. Hi all, I was trying to find a resource online that would explain how to use the chip to shift between 5v and 3. I’m assuming this means that the chip will operate at 3. Regarding this, I have 2 questions: I understand this is not great practice for supply lines, but would it be suitable for a low current application such as this?

I remember reading a post where GrumpyMike explained why a resistive divider would fail if too much current were drawn but I can’t find that at the moment. If this is not appropriate, could I supply the chip with 3. Am I correct in my understanding that the output voltage level will be equal to the voltage at Vcc of the chip?

Now with Unlimited Eagle board sizes! Level shifting with the chip. Be sure to connect grounds. Don’t you have a 3.

Didn’t even think about that though, thanks for the suggestion. I might just go ahead and add a 3v3 regulator to my board design, although I am a little concerned about power consumption with an additional regulator on board since the project will datwsheet rechargeable battery powered. I could use a 5v tolerant RTC like the ds but I am interested in using the trickle charge feature as I plan on using a supercap instead of a battery backup for reliability.

Basically, I want to never have to worry about replacing a battery as my design is going to be more or less sealed. Add a boost regulator to take supercap and maintain 3. Need a 10uH inductor, get all the life out of a charged cap. Docedison Faraday Member Posts: There are several devices in that type of converter that also might work and they only require capacitors for operation, most use. Although that isn’t a real good efficiency figure it is an example of the technology and possible applications not usually covered in the design notes for that product.


I missed that the supercap is for the RTC only. You touched briefly on “Linear regulator, Don’t even think about it. Any Power used to heat the regulator won’t be available to move anything else There are 3 or 4 terminal switchers that are either boost, buck and or variable for both topologies as well as boost-buck which is neat because Vsupply can swing about the output voltage.

Lest we forget there are a lot of “Low Dropout” regulators that have an ugly fact buried on page 10 of the data sheet and that is the required internal Control Current doesn’t flow in the load like an NPN device does emitter Follower but to ground as the only way I know to do it is with a P type device low dropout. It is arguable that P type “Fets are available Now that technology took years to get to regulators, still not used in the greatest majority of last gen regs so there is a price carefully hidden and that is that the control circuits need lots more current for a given load, compared to no load.

Literally I use linears where low noise and isolation are required as they are easier to bypass that a switcher but only required when sub millivolt noise is required milliamp supply currents or there is a radio involved of any kind.

Blocking is just as good as a poor antenna as far as “Not” receiving a weak signal. Or other low noise, small signal, analog requirements.

5v V level shifting | Mbed

If there is a choice at all use a switcher. IMO and experience in designing low power battery operated solar charged devices. Apologies, should have mentioned my power source. Linear Tech has one and the web tool to make it work So does both National and Maxim, in another place here I posted a long dissertation on switchers and some labor saving tips re: The third choice is to find one on Ebay and copy it exactly after you have tested it carefully ‘usually’ those little building blocks are faithful representations of ‘reference designs’.


MY reasoning is fairly simple 1. They Work and 2. The layout works 3.

M74HC4049F1R Datasheet

The third choice would be more inline with not being able to find a layout. Much easier to Copy a layout then create one, the one you are copying has been tested, yours? The last point is switchers are noisy, LOW ESR components are required on both the input and output sides of the device and an LC filter might be required on both ends as well. The filtering is again dependent on conditions of use and working environment.

The notes and suggestions are more for higher current supplies but are applicable to your design as long as you scale them for the situation. That’s twice I have been sidetracked. The original post referenced a for a level shifter, go look for a NXP app note AN and read it, might save you some issues re: I plugged in 2 bi-polars and a si diode and base current limiter resistor and that circuit worked as well, I didn’t however test that one beyond simulation.

Although the circuits are bi directional they work perfectly one way or the other as well. I can’t say I’ve understood everything you’ve said in this thread, but I can’t say I haven’t learned anything from it either!