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Questions tagged [level-shifting]

Level shifting is the process of converting between different logic levels. E.g. from 0-3.3 V logic to 0-5 V logic

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Understanding 5V to 1.8V UART level-shifting circuit

Hopefully it's OK to ask very basic electronics questions here. I had a TTL 5V UART cable, however the board I had only accepts 1.8V max. So I found some online schematics that uses resistors and a ...
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59 views

4.5 V on gate of Mosfet while switch open

I have a strange behavior with the circuit below. (the bidirectional logica level should be read as: VL = Voltage Low GNDL = GND Low VH = Voltage High GNDH = GND High L1 = Low channel 1 (I did only ...
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55 views

Level shifting: from 0-3.5V range to -2/1.5 range

I have a signal (digital) which has output levels of 0V (logic 0) and 3.5V (logic 1). I would like to know if it is possible to shift it between -2V (logic 0) and 1.5V (logic 1). I found here on ...
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84 views

How to find a truly bi-directional level shifter?

I'm trying to create an interface PCB to a 32 channel USB GPIO device which has 3.3v IO, and I want the flexibility to use 1.8, 3.3 or 5v - across all pins, or at most in 2x banks of 16 - I don't need ...
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Level shifter using BJT schematic

I was reading the book Analogue electronic circuits and systems, by Amitava Basak, when I stumbled in this level shifter circuit that uses BJTs instead of the usual mosfets. See the below picture. ...
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66 views

Using a Dual Bidirectional I2C Bus Voltage-Level Translator

I have a module that uses this ADC powered with 3.3V (MCP3422): Datasheet Now I would like to communicate with it over I2C using an Arduino Mega. The problem is that the Arduino's I2C is operating on ...
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160 views

Protecting a 3.3V circuit from 5V power supply

I'm designing a dev board for 3.3V parts. On the dev board, I will have a header for an "FTDI Friend" USB-to-Serial converter. The FTDI part can supply Vcc to the target board. However, FTDI parts ...
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79 views

How can I build a versatile high voltage translator with an output in the negative and positive range?

Looking for advice on how to build an adjustable voltage translator. Input is standard 1V8 logic, but output HIGH is in a selectable range of +3 to -3V, while output LOW is way down in a selectable ...
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39 views

Digital signal integrity & grounding

I have a battery operated device with an old B&W LCD in it. I'm tapping to the display bus and would like to input it into an FPGA for some processing. The bus includes vertical and horizontal ...
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104 views

UART RX in VHDL

I have to set up a UART transmitter and receiver using a Spartan 3 board. I've got the transmitter set up already and verified it with the arduino terminal using this FTDI breakout.The receiver is ...
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77 views

Is my understanding of this level shifter correct

I am considering using this TI LSF0102 level shifter in my circuit - but would like to understand, based upon its datasheet, if I have my understanding correct. It says it has a 100mA current rating, ...
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117 views

Why is this considered a slow logic level shifter?

I'm working on a project where I have to do some unidirectional logic level shifting. I'm not able to get any chip to do it at this moment (it's late at night) so I looked up some DIY solutions and ...
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2answers
96 views

Is my understanding of this level shifter correct?

I am considering using this TI LSF0102 level shifter in my circuit - but would like to understand, based upon its datasheet, if I have my understanding correct. My aim is to be able to supply 3.3V ...
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1answer
176 views

Level shiffter (3.3V / 5V) for controlling transistors

Is it possible to control the base of the transistor using the level shift chip (3.3V / 5V)? I want to use the SN74AHCT125 level shift chip. Transistor BC337-16
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38 views

Weak output from TXB0104 at 1.5MHz

I'm driving a TXB0104 translator from 3.3V logic on the B side, VccB is 3.3V, VccA is 2.5V, OE is on VccA. Both supplies are solid. It's on a breadboard. (https://www.sparkfun.com/products/11771). The ...
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58 views

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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37 views

Mixed digital/analog rails and level-shifting components best practices

I am designing a board with a ±2.5V analog domain and a 3.3V digital domain where space is at a premium. Digital and analog grounds only connect at a single point near the supplies. As such I am using/...
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1answer
160 views

What's wrong with this single-transistor level-shifter?

I was trying to step up the output of a 3.3V microcontroller pin to 5V for communication with another device. I wanted to do it with a single bjt, and found a good design for doing that here Single ...
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1answer
46 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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1answer
123 views

What's the purpose of using PNP transistors on I2S bus?

What could be the reason of using these 3 PNP transistors on I2S bus (LRCK, BCK and DATA pins)? The DAC used in this schematic is PCM5102. I know for sure that this DAC would work without these ...
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162 views

What is wrong with this voltage shifter?

I need to do voltage shifting (3.3V Papilio FPGA <--> 5V RAM chip). Most of the pins are output 3.3V -> input 5V, and 3.3V qualifies as "high" to a 5V device, so I can connect them directly. The ...
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0answers
53 views

1.8 V to 5.0 V level shifter with low delay and low rise time

i have a problem with finding the right components and circuit for the following problem. I have a device that is producing trigger signals with a length of 100 ns at a amplitude of 1.8 V (left part ...
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1answer
80 views

How do I remove the offset from the DAC output and change the range?

This DAC has an output range of 1-3 volts. Here's the datasheet: Datasheet I'm getting pulses with different amplitudes, frequencies, duty cycles and widths varying from 0.2 ms to 2 s from the DAC. ...
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67 views

74AS TTL to CMOS pull up resistor and maximum speed (or lowest delay)

Hello I have to pilot a CMOS input 5V chip device with a 7474 flip flop with the lowest possible delay to minimize clock jitter. Signal is about 11.3 Mhz I have two options: 1) 74HC74 (CMOS ...
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1answer
43 views

Weird level shifting issue only when connected to IC chip

I'm connected to a 5v heat-pump to control it via serial. I'm using a level shifter to shift between the two as the heatpump is 5v and the D1 is 3.3v shown in the scope images below. My issue is I can'...
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2answers
78 views

Convert CMOS-level signal to microphone-level (0..3V --> -1..+1V)?

I'm building a microcontroller circuit that feeds its output into a microphone input of an audio recorder. The output is a square wave. (Think old-style 3.5mm Square credit card readers). What can I ...
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1answer
249 views

Level shifting with 74HC245 3.3V to 5V not working for WS2812b [closed]

I'm trying to drive a strip of NeoPixels/WS2812b using an ESP8266 controller. To do so I'm using an external power supply (5V/10A effectively more like 5.6V) and a 74HC245 to shift the 3.3V data line ...
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2answers
189 views

2.8V to 5V conversion not working as it should. Why?

I'm using an arduino Leonardo clone (SS Micro) who works on 5V logic only, but has also a 3.3V output for powering devices. I'm interfacing it with a breakout board TOF sensor, the VL6180. This ...
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1answer
63 views

Best way to transform multiple digital signals from 12V to 3.3V

I am looking for the best way to transform multiple (more than 10) 12V digital signals down to 3.3V I know some ways to do it, such as voltage dividers, make use of BJT or MOSFETs, or even ...
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1answer
41 views

Automatic level shifting

I have a signal which can have a different offset voltage based on the requirements. However, I need the voltage to start at zero. Since the offset is variable, I was hoping if there are any ...
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2answers
318 views

How to monitor an Alternator exciter wire with MCU?

I have a internally regulated vehicle alternator which uses a conventional battery light wired in-between the exciter terminal and positive. Obviously when the alternator isn't turning the exciter ...
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1answer
93 views

PC to Rasberry Pi Serial Communication

Im trying to communicate to my pc using my raspberry pi using a software called Docklight. I'm using a serial cable (that i ripped apart) and my breadboard as shown below. Now, you can also see I ...
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66 views

Bidirectional Logic Translator translates to 2.8V instead of ~5

Considering the below PCB with the following scheme, with components inserted, with DC+ connected to a relay's DC+, DC- to DC-. When CH1 is connected to the relay, the voltage between HV1 and HGND is ...
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Does Level Shifting for I2C also work for UART?

This is a widely used circuit for level-shifting I2C signals that will be familiar to many of us here: simulate this circuit – Schematic created using CircuitLab Can it be used for shifting ...
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72 views

Active analog attenuation with OPA2340

I wish to have active analog attenuation circuit. Following this page, I got myself some OPA2340. I use the B-side to keep the numbering somewhat intact. I go with the design on Figure 16-2 (p. 14/...
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47 views

USB interface while running micro at 2.5V

I'm doing a layout for someone who has asked for a USB interface on a micro that is running at 2.5V. As far as I can tell after researching this, you can't run USB down to 2.5V. So, I did a bit of ...
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188 views

converting 220v ac sognal to 5v or 3.3v signal

i need to convert 220v signal to 5v or 3.3 v signal if push button pressed.. i tried the following circuts: 1)using neon lamp and ldr: **this circuit works fine and do what i need but if push ...
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2answers
148 views

logic level converter does not get to 5v

I'm trying to control a 2 relay module with an Esp8266 esp 12-f. After a while, I realized that the GPIO from the ESP8266 was not going to drive the 5v needed for the relay to be activated. I only ...
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1answer
68 views

Replacement IC for CD4054 [closed]

I'm looking for replacement IC for CD4054, but I can't find any other part that would work like CD4054 in level shifting. What I would need (from CD4054 description): The CD4054B may also be utilized ...
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1answer
81 views

5V to 3.3V Converter

I have a problem in connecting Raspberry PI to an MCP3202. I am using MCP3202 at 5V and knowing that raspberry pi works on 3.3v. I have found a solution to convert from 3.3V to 5V using 74HCT244. And ...
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1answer
195 views

logic level conversions for opto-isolators in digital input acquisition

This isn't my usual job, I'm not an EE, but I want to give it shot... This question concerns developing an interface board to connect a device (DUT) to a test system in a manufacturing scenario. ...
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1answer
40 views

Digital pulse converter from 3.5v to 10v [closed]

I have flow meter generating pulses at TTL that is 3.5v. My pulse counter needs 10v pulse. How can converter 3.5v pulse to 10v so that it can count. Will DC to DC converter like here https://www....
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1answer
49 views

Debugging a op-amp based comparator

I am trying to build a high frequency (~ 5MHz) level shifter circuit. For this purpose, I designed a comparator circuit based on TI's THS3491. The circuit schematic is shown below: simulate this ...
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1answer
57 views

Isolated three level pwm LTSPICE

I am doing a simulation on LTSpice of a three level ANPC. The ground is connected to the neutral point (i.e in the middle point of the DC input) and the gate drivers are isolated by using a DC DC ...
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1answer
42 views

Bias T to level shift output from oscillator

I am using XOR gate HMC851LC3C to get an ultra-short pulse (200ps range). This logic gate requires inputs in the range of -2.5V to 0.5V. However, RF signals from my oscillator is sine wave -1V to 1V. ...
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245 views

correct use of MAX3232 for a single TTL to RS232 connection

I am using the MAX3232 chip for doing TTL to RS232 conversion. Datasheet available here: http://www.ti.com/lit/ds/symlink/max3232.pdf The chip is dual channel, but I only need to use one channel. I ...
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3answers
109 views

Positive Level Shift a Clock Output using Diode?

I need to level shift a 26mhz 1.8v clock output by .7v on both the high and low side (so clock swings from .7v to 2.5v on output). Would a simple diode/resistor setup like below work for this? ...
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1answer
93 views

Op amp level shifting with LT1028

I have been using LT1028 in a lot of my projects to amplify bipolar signals before digitization with a (bipolar) analog-to-digital converter. Now I need to use a 5 V unipolar ADC and am trying to ...
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1answer
186 views

Is a TXB0108 apt for level-shifting in SPI programming?

I plan to use a TXB0108 to level-shift between the cheap CH341A programmer voltage and the Winbond W25Q64FW from 3.3V to 1.8V On the silicon I can read: ...
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58 views

Level Shifter, how to minimize power dissipated

In the above circuit used as level shifter, I would like to know if Changing all Resistances by a factor of 10 would still give the same result. The reason I'd like to increase the resistances is to ...