5v to 12v logic conversion

[jon.was.here]

Hi!

I am in need of an IC that will translate my 5v logic from a microcontroller to 12v. I need it to source current, preferably 100ma and have at least 6 channels.

Is it possible to use a cmos 4050? The datasheet says it converts hi to lo, but I have seen schematics using this chip for lo to hi.

Is there a better choice than this chip?

Thanks for any help.

 

[Papabravo]

I'm quite sure that 4000 series CMOS chips will not source 100 mA. A high side switch should do the job just fine. We use the MJD350 in our products.

 

[Papabravo]

I'm quite sure that 4000 series CMOS chips will not source 100 mA. A high side switch should do the job just fine. We use the MJD350 in our products.

 

[audioguru]

Why not look at Texas Instruments dataseet for their CD4050?
It typically sinks 100mA (with a 5V loss) and sources 30mA when its supply is 12V.

 

[jon.was.here]

Yes, I was asking about the CD4050 in particular, but I am open to any suggestions.

The data sheet for the CD4050 states that it is intended as a "HIGH-to-LOW logic level converter".

I was thinking that, in theory, the CD4050 will sorce 12v from an input of 5v, if supplied with 12v. I wasn't sure if, in practice, it could be used in that way.


Thanks again.

 

[Papabravo]

Why not look at Texas Instruments dataseet for their CD4050?
It typically sinks 100mA (with a 5V loss) and sources 30mA when its supply is 12V.

I'm of the opinion that if you want a 12V output that sources 100 mA, you should design for a 12V output that meets the requirement and not use a screwdriver to hammer a nail so to speak. Of course you could always modify the original requirement and use the device you have in mind. Also, I don't recall if the input thresholds are Vcc/2 or something else.

 

[jon.was.here]

I'm not sure what you are suggesting. My outputs are from a microcontroller, do they make 12v microcontrollers?

 

[Papabravo]

I've not seen a microcontroller since the RCA 1802 that would operate at +12V. I know that you have a microcontroller with a VCC of +5V, and I know you want an output that will source 100mA at +12V. The CD4050 cannot source 100 mA @ 12V DC. If you want an output that switches between 0V and +12V and will source and sink a particular amount of current, then you need to define your requirements. Once you have the requirements firmly in mind you can evaluate an IC against those requirements or you can design a level shifting transistor switch that will meet those requirements.

 

[on1aag]

Hi Jon,

You could use a 74LS06 to drive PNP or P-channel mosfet
transistors. The 74LS06 has six inverters with 30 volt open
collector outputs which will sink up to 30 mA.

SN74LS06D datasheet pdf datenblatt - Texas Instruments - HEX INVERTER BUFFERS/DRIVERS WITH OPEN-COLLECTOR HIGH-VOLTAGE OUTPUTS ::: ALLDATASHEET :::

on1aag.

 

[phil7890]

Hi!

I am in need of an IC that will translate my 5v logic from a microcontroller to 12v. I need it to source current, preferably 100ma and have at least 6 channels.

Is it possible to use a cmos 4050? The datasheet says it converts hi to lo, but I have seen schematics using this chip for lo to hi.

Is there a better choice than this chip?

Thanks for any help.

Maybe try a MIC2981. https://www.electro-tech-online.com/custompdfs/2008/05/mic2981.pdf
Available at Digikey and other suppliers. Good luck and have fun, but don't turn on 6 outputs at the same time because there's a limit. If you really need 100 ma x 6, then maybe use 2 chips here.

 

[Papabravo]

A PNP Darlington like the following should be more than sufficient. You can drive it directly from a processor pin. No need for a pullup to +12V which will generate considerabl heat. The TO-220 package will be more than happy to handle the 100 mA.

https://www.electro-tech-online.com/custompdfs/2008/05/TIP125.pdf

If you want symmetrical drive you might want to consider the Half-H bridge driver. It is very common in motor control circuits. something like the following:

https://www.electro-tech-online.com/custompdfs/2008/05/sn754410.pdf

 

[audioguru]

A PNP Darlington like the following should be more than sufficient. You can drive it directly from a processor pin. No need for a pullup to +12V which will generate considerabl heat.

If its emitter is at +12V then its base is at about +10.8V which is way too high for the output of a processor.
It would be tricky to design a voltage divider to allow a max of +5V at the processor with the darlington turned off and stll turn on the darlington when the processor output goes low.

 

[Hero999]

What's worng with using a couple of transistors?
**broken link removed**

For a 100mA load, make R3 1k and R1 10k. R2 is optional, it just helps the transistor to turn off more quickly.

If you worried about space, then use surface mount parted for the transistors and resistors. They're easy enough to solder prociding you have a soldering iron with a fine enough tip.

 

[Papabravo]

If its emitter is at +12V then its base is at about +10.8V which is way too high for the output of a processor.
It would be tricky to design a voltage divider to allow a max of +5V at the processor with the darlington turned off and stll turn on the darlington when the processor output goes low.

I was unclear. My "direct" connection still involves a base resistor. It might require a diode to +5V as well to relieve the diode protection circuit on most CMOS pins. The two transistor circuit works fine for pins that can source current, and can be easily modfied for pins which can only sink current.

 

[jon.was.here]

Thanks hero999! I have used that circuit in the past, and it works great, I was just trying to save some space by using an IC instead.

 

[jon.was.here]

phil7890, this chip looks like it would do exactly what I want, Thanks!

 

[jon.was.here]

Thanks everyone for giving me things to think about, I really do appreciate the help.

Is there any way to search threw all of the transistors and IC's available, or do you have to just memorize all the thousands of part numbers?

 

[phil7890]

oh yah got this particular Micrel chip memorized because I was looking for a high-side driver a year or two ago (otherwise I normally just use Digikey as a search engine because the parts for my projects will be coming from there). Be sure to have a large copper fill on the PCB under the chip to conduct the heat away, add a big cap near the V+ pin, ground the unused inputs, etc. standard stuff. Good luck and have fun...

 

[DigiTan]

Is there any way to search threw all of the transistors and IC's available, or do you have to just memorize all the thousands of part numbers?

Just like people have favorite restaurants or movies, most have a personal list of favorite components. Or at least trusted brands. Parts catalogs are really good for side-by-side comparison.

And then, some parts are just a lot more well-known than any other. The 741 op-amp for example is heavily outdated, yet it's #1 among college students because it has brand awareness.

 

[Papabravo]

...
The 741 op-amp for example is heavily outdated, yet it's #1 among college students because it has brand awareness.

Until they try to do something it can't do.