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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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 ...
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5V Input and Output interfacing with 3.3V GPIO [closed]

I have a device (a motor drive) with 5V logic. My controller is 3.3V. I draw the two circuits. The right sides are fixed in the device. I have some exact questions about calculations. -...
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Combining 5V and 3.3V SPI

On a current project I need to interface several SPI slaves to an ATSAMS70 MCU. The MCU, and some slaves, are operating at 3.3V logic levels. Other slaves need to operate at 5V, so I need a level ...
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How to connect dissimilar but close logic voltages between a chips logic out and a chips input enable pins

I have two chips and I would like the logic out of one chip to control the chip enable pins of another chip. I am just not sure how to do it. I have a chip with an output of 3.6v with logic on and -1....
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ADS1115: Using 5V supply instead of 3V, do I need to increase the logic level signal from 3V to 5V?

I am using a microcontroller that has a 3.3V Logic level output. The microcontroller is connected to ADS1115 via I2C pins, and the ADS1115 can be powered with 3.3V or 5V depending on the range of ...
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3 answers
170 views

Unidirectional level shifter 1.8-5V -> 3.3V

I'm looking for a circuit/IC to shift logic levels between 1.8/3.3/5V and 3.3V. This is to connect various devices via UART to the ESP8266. As such, I only need unidirectional translation - the ...
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Maximum input voltage Black Pill

I have a sensor outputting a 0.8 - 5.0V signal, where this analog signal is read by a 16-bit ADC, the ADS115. The ADC is capable of reading the maximum 5V signal since I am powering the ADS with VIN = ...
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Selecting a flyback diode

According to the schematic below , where J15 connects to solenoid B11HD-255-B-3 and solenoid B11HD-255-B-3 is rated 19V, 90W, what is the technical approach to selecting a flyback diode? (D15) I have ...
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Understanding MOSFET Transfer Characteristics

I am trying to build a control board to turn on and off various 12v devices with a 3.3v logic. In my hunt for the right MOSFET (have use AO3400 for smaller LED), I'm now looking for something that can ...
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Changing voltage level from an incremental encoder from 5V to 3.3V for my Raspberry PI Pico ADC pin

Edited I want to read data from my DC machine through a Sendix 5000 (encoder datasheet) incremental encoder with a Rasberry Pi Pico. Optical encoder with RS422 output and 5VDC supply. The HIGH ...
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Gate of Logic level MOSFET connect to Esp32 gpio

I want to use IRLR024N logic MOSFET to switch on/off a Sim800L module. This module consume 2A for 500μs and then consume only 200mA. I supply this module with 4V. This MOSFET able to switch on this ...
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How to understand this combinational cyclic circuit made of interconnected SR latches?

I'm trying to understand the following circuit, or better said, what must be the approach to analyze other similar ones: What I'm doing for now is forget about the clock signal and the ...
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Can I connect the pull-up resistors of I2C lines to 3.3 V on a 1.8 V device?

I need to use the following sensor in my project : AS7341 (ams). It is a spectrometer whose data are accessed through an I2C inteface. The datasheet can be found here. It is stated that its power ...
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1 answer
247 views

TMC2209 why are separate motor and logic voltages needed?

Why do motor drivers require separate motor voltage and logic voltage? I am looking to use a TM2209 stepper motor driver. Below is a schematic of how I intend to power it. I'll also be using a MCU, ...
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What are the usual logic voltage levels in MCUs and other modules?

It's a 100% beginner's question. Assuming that I have a device with VCC = 5 V, is it true that HIGH level will be always something around this 5 V and LOW level will always be something around 0 V? Or ...
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For the DVR8825 IC chip (not the carrier/module), nSleep and nReset need to be HIGH, why does connecting them to the IC's 3.3V out not work?

A breadboard prototype was made using the DVR8825 carrier/module: A microcontroller's HIGH was connected to nReset and nSleep. Now a prototype was made using the IC/chip. It's 3.3V output was ...
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MCP23017 Expansion HAT logic voltage

Does anyone know the voltage range for the MCP23017 HAT - 32 channel I/O Expansion HAT's logic pins to register a HIGH signal? I know the supply voltage range is from 1.8V-5.5V, but I'm assuming it's ...
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5 votes
2 answers
275 views

Gate resistor with "logic level" MOSFETs

I need to drive 2 logic level MOSFETs from digital outputs of a microcontroller (3.3V). These will be used to drive a low-power push-pull converter at 500 kHz. I have identified these "double&...
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Level shifter for Neopixel connection guidance

I want to use a Neopixel LED strip, with 20 LEDs. I am using an ESP32 chip. Hence I need a level shifter. I have decided to use the 74HCT04ADG because it is cheap and most importantly still in stock ...
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Using a diode to clamp a 24V logic output to 5V

I have a controller board (the Teknic ClearCore) in which output signals are pulled up to 24VDC. I am trying to interface with a TLC5947 LED driver IC rated at 5V maximum control input voltage. The ...
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3 answers
420 views

Bi-directional level shifter for serial communications

I want to know if I need to use a bi-directional level converter to send data from an ESP32 to a 5V display, using serial communications (TX and RX). I understand the serial communication is uni-...
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2.8V UART to 3.3V and 5V MCU automatically

I'm designing a PCB of SIM800C Module. Just to improve myself and it is my first project so I'm a noob sorry.. I want GSM module to communicate(from RX,TX pins) with STM32, Raspberry, Arduino. But the ...
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Why are *actual* RS232 transceivers RX thresholds so narrow?

I'm having horrible communication issues with an RS232 line. It's near a fat load (not good) and it's a printer (so the comm errors are literally visible). After investigation I actually detected the ...
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2 answers
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Logic level converter from 29V to 5V schematic

Does it looks a good schematic to do a proper 29 V to 5 V logic level conversion, any improvements or suggestions?
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I2C voltage levels and inter-operability with Sparkfun Boards

I'm trying to design around Sparkfun's I2C products to work with Adafruit sensors, specifically Sparkfun's I2C Multiplexer, Differential Endpoint, and Differential Midpoint. From what it looks like, ...
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2 votes
3 answers
750 views

Logic Level Shifter 24/12 V to 3.3 V

I have a ESP32 and Industrial Sensor with voltage output 0-12 V and 0-24 V. How can I interface 2 logic levels with my 3.3 V ESP32? Can I use a BSS138 or do I need another module?
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Voltage output of a sensor with 3.3V & 5V supply

I want to connect Sharp GP2Y1014AU0F Dust Sensor with an ESP32. According to the datasheet, the VCC can be from 0 to +7V (5V recommended). With Vcc = 5V, the sensor output voltage varies between 0.6 ...
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385 views

Differential Signaling and RS485 difference?

I am trying to wrap my head around the difference between differential signaling (mainly LVDS and LvPECL) and RS-485. All seem like differential signaling for serial communications. From the TI Page, ...
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What can I do to see only the logical values in the MOSFET input?

(Animated GIF of the simulation is here) This is a simple circuit that makes the MOSFET turn off, as the temperature of the NTC thermistor rises. As you increase the temperature in the diagram, the ...
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Pulse duration detection evaluation (opto) LT-22222 from dragino

My question seems simple but i can't find the answer on documentation. (or I don’t have enough skillz) I have this energy meter with pulse output: https://cdn.store-factory.com/www.compteur-energie....
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Will this interface work? HCSL Clock interface

I have an HCSL interface and I want to make sure it will work correctly. The oscillator is a AX3HAF1-125MHZ part and the receiver is the NXP LS1046 device. The specs for the oscillator are: Output ...
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What is the purpose of these logic level enhancement mosfets in this schematic? [duplicate]

Below I've included a schematic that belongs to a adafruit light sensor, the VEML7700. The output of the light sensor is fed into the source of a mosfet which seems to always be ON since the gate is ...
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Non-monotonic signal crossing VIL and VIH

I'm using a logic buffer SN74LVC2G125 (SN74LVC2G125 datasheet) which is powered by 1.8V and has VIH and VIL of 1.17V and 0.63V, respectively. If I have an input signal like below, could the buffer's ...
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Why does the 74LS32N behave like an AND gate?

First of all I am a beginner. I am practicing with the 74LS32N (OR Gate) IC , I noticed that it behaves like an AND gate instead of an OR Gate. Only when both the inputs are 1 , the output is 1 , (Led ...
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8-channel/octal equivalent of 74HC125

I have a 12v powered 16-channel relay board, that required 5v logic level signals to control the relays. However, I am using a Raspberry Pi to control this, which has 3.3v logic level outputs. I have ...
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74HC08N doesn't latch [closed]

I am using the 74HC08N chip. Why doesn't the first AND gate latch itself? I have connected the output of the first AND gate to its own input. I have used two resistors, the one on top is a pull-up and ...
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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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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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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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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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1 vote
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529 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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What are 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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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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4 answers
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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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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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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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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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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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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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