Questions tagged [logic-level]

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

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Data Logic Levels Sent From Sensor Are Not Going All The Way Low

I'm having issues receiving data from a 3.3 volt logic level R503 Fingerprint Module that is sent via it's Tx pin using UART. The logic levels are converted to 5 volts using a bi-directional converter....
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57 views

In a NOR gate not connected to any power supply, how can the output be '1' if both of the inputs are '0'? [duplicate]

I was reading about SR Latches and this very weird (and silly) question popped up in my head. Here, when A and B is 0, then Q is 1. Suppose that this NOR gate is lying in air, not connected to any ...
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63 views

Is it possible to use a MAX232 to convert 0 to 5V PWM to 0 to 12V PWM to input to a motor driver requiring 0 to 12V PWM logic?

I'd like to drive a 16kHz PWM signal at 0.5mA into the input of a motor driver expecting logic levels of 0V for LOW and 12V for HIGH, and expecting a PWM signal around this frequency. The PWM signal ...
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voltage level handled using optocoupler [duplicate]

I want to program at89c2051 chip. I am referring circuit diagram where the optocoupler is used to handle the 2 voltage levels (+12V and +5V). i didn't understand how Pin A0 and A1 will control the ...
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multi-level NAND circuit simple conversion

i am working on understanding the NAND conversion I have just got the basics of two-level NAND conversion and when i went to the book example for a multi-level NAND coversion it used solved an example ...
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37 views

How to read a 5.5V IC push-pull output using a 3.3V microcontroller?

I have two devices that I need connect, one fed with 5V, the other fed with 3.3V, and I also have a level-shifter, TXS0108E, that allows communication between two circuits, one working in 3.3V and ...
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43 views

Correct usage of 74LCX245 logic level converter IC

I am designing a PCB where I need to convert some 5v logic signals from a Wiegand reader into 3.3v logic that a Raspberry Pi can understand. I have been using a resistor-based voltage divider before, ...
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64 views

Amplfying MCU 113kHz output

I am using an ESP32 to generate a 113 kHz, ~3,5 V output. I then intend to amplify this to a ~50V peak-peak waveform. For that I am trying to use a DC-DC converter based on the LM2577 (to boost from ...
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2answers
88 views

MOSFET 24V high-side switch

I'm trying to control 24V solenoids using logic level inputs at 5V. The following circuit works when replacing both power loops with a single 9V battery, except that the voltage across the gate and ...
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64 views

Logic level switch controlled via ground (0v)

simulate this circuit – Schematic created using CircuitLab Hello, all. My goal: to convert a ground signal pulse into a +5v signal pulse. My question: How on earth do I do this? Backstory: My ...
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36 views

Connecting signalling lines of the multiple devices with different power sources

I started to develop a simple device and this question arose. I need to make some uC device that will be connected to the PCI-E bus via M.2 socket. And I need this device to be working even during ...
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24 views

How to make a parallel connection between two components when each has its own voltage?

I have a problem to determine whether or not it is safe to make a connection as picture below. Currently I have a H7EC counter connected to a switch and it has 2.7 V across terminal 1 & 2 on the ...
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52 views

Attiny13 affects USBtiny programmer logic voltage levels

I wanted to port a simple program from an Attiny85 to the cheaper Attiny13. To make sure everything would work properly I started trying to upload a simple blink program to the MCU but could not get ...
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54 views

Using a Non-Inverting Buffer for Level Shifting

I've got a project that involves a 5V Arduino and a Raspberry Pi Zero (3.3V) that need to communicate through a serial interface. The easy solution here would be to connect them through USB, but I'll ...
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Correct MOSFET for logic level switching

I'm looking to switch a 12 volt 0.5A and 2A load using the raspberry pi's 3.3v GPIO pins. From what I've read a MOSFET is the best fit for this application but I'd like to avoid wasting energy as heat ...
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78 views

Is there a component/method that can take any signal, then increase it to 5 volts no matter how small the signal is?

I was using a logic level MOSFET that should turn on when a voltage other than 0 volts between two points is detected. My problem is that the voltage is at times less than 5 volts and probably won't ...
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How to do serial communication between 3.3V and 5V devices using THT components?

I know that there are many questions dealing with logic level conversion/shifting between 3.3V and 5V devices, but my goal is to do do this with standard breadboard parts, so either discrete parts or ...
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32 views

Compatibility of devices with different voltage thresholds/noise margins/static disciplines

tl;dr included at the bottom. Suppose we have two logical buffers from different logic families, where buffer A drives buffer B. Buffer A has the following voltage thresholds: \$V_{OH}=8\ V\$, \$V_{...
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NPN BJT NOR gate to drive LED. Base resistance problem

Here's a circuit I'm trying to get working : I have two digital signals (B and C in the diagram) coming from a CD40174 flipflop. I use these to light up two LED's. I also use these as the input for ...
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Why a CPLD input pin behaves almost like an output pin?

I want my CPLD (a MAX II CPLD, EPM240, see datasheet) to accept an S/PDIF input using an optical receiver with TTL-compatible output. I tested the receiver alone: when giving proper power and optical ...
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48 views

What happens when both sides of a bi-directional MOSFET logic level shifter try to drive it and how to make sure terrible things don't happen?

I understand the principle of operation of a simple MOSFET logic level shifter like the one described in this question. However, the answer to that question only states what happens when we apply ...
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Would this circuit interface be a safe interface between full duplex and half-duplex UARTs of different logic levels? [duplicate]

I'm primarily a SW developer who dabbles with electronics. I needs to interface my SoC's HW full-duplex UART with an SDI-12 compliant sensor, without burning either of them and hopefully without ...
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Logic Level MOSFET Behaving Unexpectedly Driving PWM Signal to PSU

I am trying to control a MeanWell dimmable PSU with an Arduino. Since I do not want to exceed 60% of the output of the MeanWell, I want to use a 0 to 6V PWM signal. I figured a quick and dirty way to ...
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1answer
68 views

Connect to LIN bus with logic level shifter as transceiver

Is it good idea to connect my microcontroller to LIN bus with logic level shifter (5 <=> 12 V) instead of factory LIN transceiver (MCP2003, TJA1020, etc.)? As I understand, LIN transceiver just ...
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65 views

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 ...
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30 views

CPLD High-Z pin - safe to drive over the high logic level voltage?

I have a CPLD connected to a BUS and an EEPROM. The bus has 3v logic and is 5v tolerant. The CPLD is 3v only. If I configure the CPLD pin to be in the high-z state and the eeprom drives that pin to ...
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129 views

Logic Level Converter for Negative Voltages

Here is logic level converter mostly used for converting signals between 3.3V and 5V. (Other positive levels such as 1.8V are also possible). What if I want to convert from 3.3V to -5V logic (negative!...
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which kind of design of level shifter suitable for high frequency data transfeing in range of 1MHz? [closed]

A circuit needed to convert 3.3V and 5V logical voltage. However, the issue was that the circuit was supposed to handle very high data transfer at or above 1 MHz and up to 16MHz. I thought of ...
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82 views

Usage of 74LVC1T45 in open-drain case

I want to do one 'universal' or 'multiprotocol'-capable IO block and currently thinking of using 74LVC1T45 level translator to do the communication between two different voltage leveled systems. I ...
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3.3v input in a 1.8v logic question

In a board design there's a mistake in the voltage level to control a reset pin (Signal RESETB). It should be 1.8v but it is driven by a 3.3v level. The datasheet shows the next info: It looks like ...
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Logic-level transistor not switching

I am trying to use a transistor to drive a lamp from a Raspberry Pi (3B+) and I went after one that can be switched by the 3.3V logic. I found the FQP50N06L to have a max Vgs threshold of 2.5V, so it ...
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162 views

~150 WS2812b LED's with Pi Zero and SN74AHCT125N

I'm planning to control about 150 WS2812b LEDs with my Pi Zero and a 5v 11a power source (PC molex connector). Following this guide: https://www.thegeekpub.com/15990/wiring-ws2812b-addressable-leds-to-...
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Capacitor to discharge upon switch open

Update Please evaluate this third attempt: This is my first electrical project, so please be gentle with me. I know very little about electronics. I'm building a machine that has a crank that users ...
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Driving a 74HC245 in one direction with 3.3V when Vcc is 5V

I have a 5V device that accepts parallel data in. That data is buffered by a 74HC245 IC (TI datasheet, NXP datasheet) where the Dir pin is hard wired to drive in ...
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44 views

Single chip level shifter from LVCMOS to 12 V

I'm working on a nixie clock based on a STM32L476RG microcontroller and HV5530 chips. The microcontroller uses 3.3 V logic while the HV5530 really needs 12 V logic, which is a pain to implement. There ...
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334 views

Raspberry Pi with 74HC14 connecting to LED strip (WS2812B)

This might be a stupid question, but I can't seem to figure out how to convert 3.3V to 5V with the 74HC14. I have a power source which can supply 5V (see the power adapter at the left), and use it to ...
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29 views

Output voltage of AT28C64B into HC CMOS IC

I am trying to load the output of a AT28C64B parallel EEPROM into a 74HC194 shift register. The datasheet for the AT28C64B states that the minimum high level output is 2.4V, which I believe is not ...
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188 views

Switching 12v pilot with 3.3v logic

I have an entry gate pilot operating on 12v. I would like to connect it to my esp8266 (3.3v) to control it over the WiFi. I would like to use 12v power line which I already have. The components which ...
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66 views

Stepping Down Logic Level of a Differential Signal

simulate this circuit – Schematic created using CircuitLab Suppose I have a unipolar, differential 24V signal, and I want to step it down for use with a 5V differential receiver (such as RS-422)...
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426 views

N-Channel Mosfet or NPN transistor for Low Power PWM Application

simulate this circuit – Schematic created using CircuitLab LED: 2.05V @ 350mA 5-6 Ohm Resistor for current regulation Hi, currently designing a circuit that controls a LED using a PWM logic ...
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57 views

Significant noise observed on channels of TXB0108

We're working with a ADC chip test setup that uses the TXDB0108 to step up 1.8V data lines to 2.5V that are connected to Kintex7 FPGA. The pin-out is as follows: VCCA is 1.8V, while VCCB is on a 2....
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46 views

How to convert a +/-12 V digital signal to 0/+5 V?

What would be a simple way to convert RS-232 +/-12 V digital levels into +5/0 V respectively? I considered an optocouple, but I can't find one that can withstand -12 V reverse voltage. I considered ...
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187 views

P channel mosfet as a switch on logic level

I'm quite confused about the p channel mosfet as a switch. I saw designs with zener diodes, other mosfets or BJTs but these seem overcomplicated. I have many P channel mosfets from broken chargers (...
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55 views

Voltage controlled connection of two signals that are at higher voltage than the control voltage

Given are two signals A and B. I want to control the connection between them by a signal C. However, signal C is a logic signal with a voltage of 3.3V for high and 0V for low whereas signals A and B ...
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243 views

Logic level converter for NodeMCU (ESP8266): Input 24V/16V (Hi/Lo), 500 Baud

I want to use a digital input pin of a NodeMCU board (ESP8266) to read a digital signal. The signal line idles at 24V DC. The logic levels are 24V and 16V. The signal speed is 500 Baud (each signal ...
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139 views

TTL to NIM logic translation Logic Gate Issue

NIM is a standard used in nuclear physics. I'm facing an issue with a logic gate being used in my TTL to NIM translation circuit, and I'm not sure what is entirely wrong with it. For a little ...
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54 views

SR Latch internal conflicts

it is known that "11" are invalid inputs for a SR Latch. But I do not understand the reason of that. I cannot see the electrical conflict in this structure: If R = 1, its NOR gate will give 0, for ...
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242 views

Can a 74AHCT IC be a drop-in replacement for 74HCT IC

I have a circuit in which I interface a radio module running on 3.3V indirectly from a 5V supply. I use a regulator to provide the 3.3V module VCC and the data is exchanged between both circuits ...
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114 views

Will using a microSD card reader with STM32 produce logical errors? [closed]

I have a microSD card reader which needs \$5\,\mathrm{V}\$ to operate. I am interfacing it with STM32 MCU operating at \$3.3\,\mathrm{V}\$. Will it operate normally when I provide only \$3.3\,\mathrm{...
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84 views

PWM logic level issue

I am facing new problems everyday at embedded system. I have designed D-SMPS and put an stm32f103 to drive mosfets.I have tested micro controller and it works well while giving outputs as GPIO.It is ...

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