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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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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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51 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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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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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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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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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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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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67 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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67 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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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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70 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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98 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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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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71 views

Would this MOSFET be suitable for use with an Arduino?

I'm looking for a MOSFET which can be controlled by an Arduino at 5V, and which can switch power on/off to a Raspberry Pi and peripherals (also 5V) that will peak around 3A of current. It's a battery-...
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Logic Level MOSFET IRLZ44N - under Wemos mini

I used IRLZ44N with Arduino Nano in order to dimm a 12v LED strip. When tried to use it with Wemos Mini - I get only 7.6v max ( when controlling a 12v source ). Probing the output pin (...
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In logic levels, why are the driver and receiver depicted as inverters?

In Digital Design and Computer Architecture (Harris and Harris), the following schematic is given , in discussing logic levels. Why are the driver and receiver depicted as inverters?
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STM32F4 and SIM800L logic level

I am currently using an STM32F401RE that I have to interface with a SIM800L GSM module via UART. In a first "toy example" I used Arduino and found no problems, but passing to the STM MCU I am unable ...
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42 views

Voh value not provided

I have this EEPROM IC where I want to check the logic level compatibility with another IC. But here Voh value is not given. I have observed this in my other IC also. Why is the Voh value not provided?...
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SPI pins logic level issue [closed]

I have ESP32 and the popular dot matrix module MAX7219 8*8 module to interface. It is connected through SPI pins. After a sample word printing on the maxtix it shows garbage outputs. Is it happening ...
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54 views

What is the purpose of Vih and Vil in the comparator's datasheet?

Looking into the MAX999 datasheet I can not figure out how to utilize information given for the Vih and Vil ...
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141 views

Do high and low side labels on bidirectional logic level converters matter?

Logic level converters like this one from Sparkfun have high side and low side labels on them. Now i have an application where I think I need to shift logic levels but the high side and the low side ...
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76 views

CAN Rx Line between STM32 and MCP2561

I discover a problem on my design, with a STM32F042K6 MCU and a MCP2561 Can Transceiver. I can send some frames on the CAN Bus but i can't receive any frames. When i put my scope probe on the CAN Rx ...
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5V digital output to 24V

I'm sure it is a simple solution but I am new to this so please take it easy. I need to come up with something to convert a 5V digital output signal from a USB-1608G DAQ device with DIO to 24V ...
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PX4FLOW (Optical Flow sensor) - Powering with 5v. Does it work with OmniNXTF7 I2C SCL/SDA at 3.3v?

I want to use PX4FLOW with OmniNXTF7 flight controller. This flight controller has 3.3v I2C SCL/SDA and no PullUp-resistors. I use the PX4FLOW only with I2C port, with 5v at VCC (not 3.3v). Does ...
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How to passively shift logic levels to drive LEDs

I have an input signal that is either 2.7V (low) or 9.9V (high). Is there any way to use passive components (excluding op-amps) to turn an LED off when the signal is low and on when the signal is high?...
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66 views

Switch from 5v to 24v - 150kHz - 20mA

I'm looking for a way to amplify a signal from 5v -> 24v. This signal is a PWM with a frequency of 150kHz. Amplified signal will have a fixed load of 20mA to power a LED with a Vf of 1.25v. I've ...
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150 views

Using Mosfet with seperate Logic Converter and Arduino

I am trying to use an IRLB3034 with an Arduino even though it is not a logic level MOSFET. I am planning on using an LM2937 12v regulator like the schematic below: The connection going off the page ...
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56 views

The simplest “adaptive” downward level shift solution?

I want to build a level shifter circuit for the RX pin of my ESP-12S. The goal is to convert any level between 3.3V and 5V to 3.3V as I might use many USB to UART breakout boards with different output ...
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Serial Communication Between Android and Attiny85

I am planning to build a sensor module for smartphone using Attiny 85 as its microcontroller. The sensor module will have a USB type A and to connect to the smartphone, OTG is required. Serial ...
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Logic leves and protocol, interfacing HP39GS to arduino Wemos D1

Im trying to connect HP39GS scientific calculator to Wemos D1 arduino. It has TTL RS-232 serial port. Pinout is somewhat: Vcc, TX, RX, GND. Looks like HP39GS protocol for serial port is not pure RS-...
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Preventing overvoltage on serial pin

I am trying to send data through serial from a 3.3v Arduino to a 5v Arduino. I assume I can't just connect the 3.3v tx to the 5v rx because, when I program the 5v one I am assuming it will send 5v ...
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170 views

NPN: Not fully sinking to GND

I'm using an NPN to pull a 12v (5mA) signal low from an MCU (logic level). My problem is that when I pull the 12v line low, 7.4v are still present at the 12v side of the line using the circuit below: ...
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How do I wire a Rasberry Pi 3B+ to a WS2812b RGB strip?

I am working on a project where I need to use a WS2812b RGB strip. I am really worried because I have already burnt 2 Raspberry Pis with my wiring. I just want to show my schematics, and be assured as ...
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68 views

Driving 12v logic from an MCU

I'm looking to drive 12v logic signals (logic level shift) from a PIC24FJ MCU, which can do 3.3v and 5v logic. In one instance, I need to switch a 12v line to LOW, and in an other, I need to provide a ...
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109 views

Component recognition from marking code

I need help to recognize a dead component from a lab instrument control board. It is part of a TTL-serial interface, arguably a logic gate or some level shifter, in a TSSOP-14 package. You can see ...
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37 views

3v3 VLogic for DG212

I am curious if anyone knows if a Vishay DG212 works with VLogic being powered by 3v3? The only test conditions the datasheet speaks of are where VL is being powered by 5v. Here is the datasheet: ...
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High level present in a pin of a non-powered IC can damage it?

I'm using a TXS0108E to convert from 5V to 3.3V and vice versa. The schematic is below: In the datasheet, in section 6, I read the following: Voltage applied to any output in the high-impedance or ...
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112 views

How to explain and possibly avoid undervoltage on I2C bus?

I've been testing different sensors for the I²C bus with two host devices: Raspberry Pi 3B (3.3V), and Sitec S4 (5.0V). Since one of them, namely the Sensirion SCD30, had communication problems every ...
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Help needed in understanding MOSFET datasheet

I am trying to find a logic level MOSFET for 3.3V operation. In my case, I am trying to compare AOD510 & AO4402. AOD510: \$\mathrm{R_{DS(on)}}\$ @ 4.5 \$\mathrm{V_{GS}}\$ = 0.004 ohm but has no ...
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Logic level translations

Have you ever had any experience with an ADG3304 IC? I've prepared a circuit which allows to translate logic levels in SPI interface. I want my circuit to be compatible with both 1.8V and 3.3V logic ...
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93 views

Logic levels on tri-state buffer,

i am working on some CPLD-controlled SPI devices that will be daisy-chained together. I will be using 74VHCT126AFTTR tri-state buffers to disconnect the SPI and Slave Select lines on the device from ...
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202 views

Does logic shifter works on analog signals?

I am using a 5V sensors (MQX Gas Sensors) that is connected to an RPi. This sensor is then connected to an ADC converter then to a logic level shifter. I just followed the tutorial I saw on the ...
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How to analyze Microcontroller input-logic-signal without ADC?

I have a signal which is fed to one of the digital inputs of a microcontroller (PIC16F18326). The signal is shown in the image-1 below. This is during the normal operation of the circuit, that means ...
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ultrasonic-sensor to Logic Level Converter to raspberry pi [closed]

Trying to connect Ultrasonic sensor to my raspberry Pi. Im aware of two methods: connect the trig to a 1k resister before connecting to raspberry pi Use a 8-Channel Logic level converter I trying ...
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76 views

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 ...
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421 views

Logic-level converter FET

I have been using the BSS138 level converter circuit for a while now and today it struck me I get how the voltage is stepped up by the FET or the BSS138 when you are applying say 3.3 V on the LV side. ...
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Question regarding MCU, Voltages and Level Shifting

I have a board with a 3.3v MCU (C8051F850 from Silicon Labs in a QSOP-24 package) but whose pins are 5v tolerant. The board is running at 5v and all the relevant GPIO pins from Ports 0 & 1 have ...
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3answers
659 views

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 ...
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57 views

Can I use TXB0104B bidirectional level shifters on the Intel 8085 NMOS CPU buses?

I want to connect an old Intel 8085 CPU to an FPGA board. The basic issue is that the 8085 works at 5V while the FPGA will not accept any voltage avobe 3.3V so I decided to use the TXB0104 / TXB0108 ...
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How can a dominant state be the one with bigger voltage difference?

I am studying about CAN buses, and there is one thing I just can't find an explanation for. I understand that the idea of a wired-and connection is, that if any node is driving the bus to the dominant ...