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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Level Shifting - Signal Scaling - Scale Analog Signal Voltage

I have a variable voltage called Vreg (Voltage regulated) which is output of switching regulator (buck converter) and is less than 12v. Also there is ANALOG Signal ...
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2answers
45 views

IRLZ44N MOSFET switch - voltage drop across brushless fan

simulate this circuit – Schematic created using CircuitLab I have an IRLZ44N with the gate connected to a 3.3v logic output pin as shown in the diagram below. The brushless fan is rated at 5v ...
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62 views

I2C Level translator 5 V to 1.8 V using MOSFET, output look weird

I am designing an I2C level translator using MOSFET. I am using BSS138 DATA SHEET. My clock can go up to 1 MHz. The output is not coming properly for fast mode plus (CLK = 1 MHz, RISE TIME = FALL TIME ...
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52 views

I2C: Do I still need pull-up resistors if I use a logic level converter? I

Electronics newbie here. I have the following setup - three Arduino Nanos, a BME280 sensor, an MPU6050 gyroscope, a GPS GT-U7 (Goovvv Tech) module and an 128x64 (1.3in) OLED display. All except the ...
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3answers
60 views

Microcontroller maximum and minimum source and sink current

I'm using the S32K142 64-pin microcontroller. I have a question about this table: What parameter does the maximum sink current and source current depend upon? The marked line in the table says that ...
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1answer
69 views

What is the output logic levels of this STM32?

I am struggling getting my head around the input and output logic levels, mostly the output levels of this STM32 (STM32F446xC/E). This table shows the output logic levels as dependent on if it is a ...
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22 views

Bi-Directional Logic Level converter 1.8V-5V using MOSFET

I need to connect an Event Detection pin (pin of the NXP NTAG 5 component) to a GPIO of the NXP i.XM6 processor. The problem is that the NTAG 5 pin has a logic level of 5V and the GPIO has a logic ...
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23 views

5v Signal to 24v Input for CNC Machine Probe

Background Info I have a CNC probe which acts just like a NC switch and opens when triggered, I am trying to modify a circuit for use with my CNC machine controller inputs which use a 24v signal to ...
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4answers
98 views

Degenerated signal at a logic level converter

I'm trying to pair a motor controller, and a bi-directional logic level converter to feed a microcontroller with a motor speed signal. Some signals have already been successfully converted, but a ...
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38 views

Question regarding isolation and level shifting

What are the requirements that make one choose between physical isolation and simple logic level shifter circuits when you have two devices communicating with each other. For example, a circuit ...
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100 views

Understanding how this bi-directional logic level shift works

I'm having a bit of trouble understanding how this logic level shift circuit works exactly. The design is from Sparkfun. Hhere is the schematic: For my application, the LV and HV are the 3.3V and 5V ...
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77 views

High current bus bars on PCB controlled with mosfet and Raspberry Pi

I need to be able to switch up to 100 amp @ 48v DC with a Raspberry Pi. I came across this video which is what I am trying to emulate: https://www.youtube.com/watch?v=dhIbZa6yg5k at 1:15 in the video ...
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25 views

load sharing circuit power supply and battery with turn off mechanism

I have my power supply VDD with 5 V. If my power supply is connected to the circuit, the MOSFET M1 should block my battery voltage. If the power supply is disconnected (VDD = 0), the transistor M1 ...
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1answer
37 views

Connecting Geiger Counters in Coincidence

So for this Geiger Counter kit from mightohm (https://mightyohm.com/blog/products/geiger-counter/), does any one have any suggestions for what circuits to build to connect two detectors in coincidence?...
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Is it safe to drive a 5V servo using a logic level shift board?

I would like to turn off and on a servo while it is not used. The LV would be 3.3V and the HV would be connected directly to s lithium battery. Could it work if I replace R4 with a servo? What problem ...
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74 views

Logic Converter driving logic level Mosfet Gate

I am wondering if anyone can comment on the feasibility of this circuit. My ultimate goal is to switch a 12V solenoid on and off using a 3.3V microcontroller, but I have had trouble so far. I want to ...
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40 views

MicroUSB to MCU interface with logical level conversion

I'm trying to interface a micro USB port to a microcontroller but I'm not sure about something. The micro USB port will be connected to a computer with a simple USB cable and that will give me a 5V ...
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70 views

Logic level mosfet wont drive solenoid

I am trying to find out why my current mosfet is not working by looking over the datasheet. Ultimately I am just trying to buy a mosfet that I know will work, but I want to understand the datasheets ...
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1answer
78 views

Problem into shifting from 3v3 to 5v using a BJT

I've encountered a problem when I've made a small circuit to shift logic level of my 3v3 MCU to a 5v signal. Probably I've misunderstood usage of BJTs. Here's schematic: As said, my purpose is to ...
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114 views

Logic Level 3.3v to 3.3v or 5v

I have a circuit with two voltage domains that need to talk to each other. One side is always 3.3v, but the other side can either be 3.3v or 5v depending on what physical hardware is connected. The ...
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101 views

Replacing optocoupler with a more reliable and durable device

I am working on a project where I need to have some sort isolation from a machine sending out highs and lows in terms of 24vdc to 0vdc respectively. And I'm using a microcontroller like ESP32 that ...
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1answer
58 views

Convert High voltage output ( 15V ) to 5 V

I want to use : DSD 70 Dual Channel Hall Effect Speed Sensor and integrate it with an MCU ( arduino ) atmega , so I have to convert the output of the sensor to 5V to be able to read it by the MCU. Any ...
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70 views

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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78 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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2answers
86 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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49 views

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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58 views

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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43 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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1answer
108 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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70 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
224 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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2answers
69 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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2answers
47 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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1answer
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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73 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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1answer
130 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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51 views

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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83 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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2answers
592 views

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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35 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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40 views

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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1answer
20 views

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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2answers
70 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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103 views

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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72 views

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
175 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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2answers
79 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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1answer
36 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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2answers
368 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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136 views

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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