Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [logic-level]

Logic level refers to the input and output voltage levels of digital logic, which is often 3.3 V or 5 V.

Logic level is relevant when driving MOSFETs directly from a digital output. Previously this was often 5 V, but today's logic ICs often operate at 3.3 V or lower. Power MOSFETs often need higher gate voltages to drive the rated current, and most manufacturers filled the gap by producing several logic level MOSFETs with a VGS(th) of 2 V or less, which can drive several amperes at 3.3 V.

Logic level is also important when connecting logic ICs operating at different supply voltages.

Further reading
Logic signal voltage levels information on All About Circuits

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Translating to "below ground" logic levels

I have an RF switch chip that is controlled by a logic signal with levels of 0 V and -3 V. I want to control this from a CPLD that's producing ordinary +3.3 V CMOS levels. Board area is at a premium in this design because I'm trying to wedge this in…
The Photon
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what are cores in real in a cpu?

i would like to know what cores at physical level are in a cpu. some mix of logic gates make a head that's called a core is it?.so one core how does it appear to be in physical level.! PLease am new to this field.Any kind of help i would be obliged…
snook
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logic input that can handle a higher voltage but output a low voltage?

I think some logic IC input can handle a range of lower voltage levels but will output at supply voltage... What is the best way to achieve an input that can handle higher levels but output at a lower level for the next stage? Some logic ICs or…
Jay
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Switch from 5 V to 24 V - 150 kHz - 20 mA

I'm looking for a way to amplify a signal from 5 V to 24 V. The signal is PWM with a frequency of 150 kHz. The amplified signal will have a fixed load of 20 mA to power an LED with a Vf of 1.25 V. I've thought about an opto like the TLP293, but too…
Singed
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When to choose active-low over active-high for a switch?

I was reading this intro article: https://learn.sparkfun.com/tutorials/logic-levels/all#active-low-and-active-high Is there a particular time when an active low signal is preferred over an active high signal or vice versa? Does it make a different…
falling cat
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Logic Level Converter not converting low logic level as expected?

I'm trying to convert 1.5V logic levels from a caliper data port to 3.3v to be able to read it with a microcontroller, using one of the sparkfun logic level converters. The product page mentions it can be used for 1.8V logic levels, so I was hoping…
JesusFreke
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Small logic level converter 3.3V to 5V

I'm working on a small group project of 25 units using ESP-12F controllers that I need to fit into a relatively tight space. The project communicates with some WS2812b LEDs and takes a 5V power source due to brightness needed. Got in a bit over my…
TechVulp
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For production boards, is a buffer IC best to translate single unidirectional 3.3v to 5v logic without inversion?

I've read plenty of advice on how to deal with 5v <-> 3v logic translation and there seems to be a ton of methods, some of which I'm clear on and some I'm not. Most of the material is geared around things like Arduino, etc... one-off hobbiest…
bcsteeve
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Do I need a bidirectional logic shifter for UART

I need to interface my Raspberry Pi to my Uno hence I need to logic shift 5 V logic to 3.3 V. I will be sending data from the Uno to Pi and from the Pi to the Uno. My understanding is UART uses two pins one for sending and one for receiving. I have…
Ageis
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Interfacing 2.85V logic modem with 3.3V microcontroller

I have Fibocom G510 modem. It has 2.85V logic level and datasheets says, that 3.3V is absolute maximum for logic pins. Maximum baud rate is 115200. Due to the limited space in the housing / on PCB I do not have space for a proper level shifter. Can…
Kamil
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Logic level shifting

I want to interface 12 VDC rated WS2815B addressable LED strip with a 3.3 VDC microcontroller. I am having difficulty finding a logic level shifter which translates 3.3 V to 12 V. Data rate is significantly high and hence fast rise and fall times…
Whiskeyjack
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PIC24 Build-In Voltage Regulator

In the datasheet of the PIC24FJ256GB206, I have read that there is an onboard voltage regulator which will drop the core voltage to 1.8V. My question is: Will the logic levels of output pins also drop to 1.8V or will they remain to go all the way to…
Tyrsz
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Which Low Input Current Buffer Chip?

I would like to get a PC to flash seven LEDs in response to program events. I plan to use the parallel port which is provided on the motherboard I am using by a Fintek F81866A "super i/o" LPC chip…
Guy
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CD40xx and SN74xx logic gates not working correctly

So, a few weeks ago I got into digital logic, and thought I'd buy some logic ICs. However, instead of doing actual research about which ones are good and which ones are bad, I just bought whichever had the most in stock on mouser.com, which just…
undo_all
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