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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Driving a load on negative rail with a positive signal

I want to turn the LED on when the 5V pulse is high. I expect a simple circuit consisting of two or three bipolar or MOSFET transistors similar to the erroneous one in the image above. I don't want ...
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23 views

NXP i2c temperature probe locking up

I have an issue with an NXP SE95 temperature probe that has been working just fine up until now on other systems. At some point, either on boot or soon after, the probe will have some sort of meltdown ...
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1answer
41 views

Why would a 5V input to a 74HC04 pull it's V_CC from 3.3V to about 4V

I have the following circuit: simulate this circuit – Schematic created using CircuitLab The SN74HC00 (from TI) has input clamps, so I am expecting the 5V logic input to be clamped to ...
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3answers
129 views

3V3 to 5V level conversion

I'm currently working on the development of some measurement equipment. For conversions I use a small ARM which runs on 3V3 and to display the results I use a graphical display running on 5V. This ...
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1answer
46 views

FET level shifter for serial does not work with inline resistor for safety

For a voltage change on a serial line I'm using a common level shifter design which uses a FET (BSS138 in this case) as so: I have two of these - one for RX and one for TX. I should add that I'm ...
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1answer
66 views

Arduino <-> BBB UART issues using bi-directional level converter (5v to 3.3v)

I am having a strange issue interfacing between an Arduino and BeagleBoneBlack over UART. The Arduino is 5v logic, and the BBB is 3.3v logic, so I'm using a bi-directional logic level converter from ...
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4answers
119 views

What is the simplest op amp level shifter?

What is the simplest op amp level shifter? That is, no gain and both inverting and non inverting configurations, for AC coupling
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1answer
65 views

Understanding 74LVC245 datasheet and current source/sink

I'm using a SN74LVC245A (datasheet) to shift 5V TTL down to 3.3V so I can read the signals with a Raspberry Pi. However I am getting really weird results (a 60Hz input signal is picked up by the Pi ...
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1answer
39 views

making sense of HCT ACT cmos “addional supply current”

I'm trying to make a low-current level shifter from low voltage (~2V) CMOS up to 5V CMOS. I had the idea to use TTL-compatible CMOS gates in the HCT or ACT families. But this line in the 74HCT04 ...
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2answers
88 views

TTL to +/- 12V conversion - what's a better way?

The context here is the pilot generator for a J1772 EV charging station. The specification calls for a 1 kHz +/- 12 volt square wave with varying duty cycle. The output is sent through a 1 k resistor ...
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2answers
151 views

Is a N-Channel Mosfet save/reliable for level shifting UART from 3V3 to 5V?

I am busy with a design that needs to connect a Raspberry Pi to an Arduino via UART. Previously I have designed a circuit that worked okay. But now I want start using SMD components and is planing ...
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3answers
78 views

I2C Level translation

In our current design, we have two devices which communicate with each other using I2C. But their I2C logic levels are different, so we need to use a level translation? Can I use a simple level ...
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2answers
60 views

Low profile i2c level shifting solution

I have a system that involves two boards and i2c communication between them. One of the boards uses 2.8V for i/o (including i2c) and the other 3.3. The 3.3V board is always the master and the 2.8V ...
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1answer
34 views

GPIO pull up to different level

I am using MSP430F235 which is supplied with 2.5V on DVCC. So, all its I/Os will be in 2.5V level. Now, I want to enable a LDO in which EN pin is tied to a different level (>2.5V is the battery supply ...
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1answer
145 views

Shift 0-1.8V logic to 0-5V logic

I'm using BeagleBoard-xM McSPI to drive an MCP42050 digital potentiometer. Before using the SPI chip itself I'll try bitbanging through 3 GPIOs (but my question relates to both configurations). BB ...
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0answers
79 views

Level shift and amplify

I searched around the forum and found this post: Analog voltage level conversion (level shift) I built a dinamic motion seat with an Arduino, H-Bridge and 2 wiper motors. The wiper motors are acting ...
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1answer
170 views

IC to interface between digital switches (12V) and microprocessors (3.3V)

I am working on an automotive general purpose ECU where I need to interface 12V digital inputs with a µC (3.3V). The PCB space is limited, so I am searching for a single IC as an interface between ...
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1answer
229 views

Converting 3.3v logic level to 5v using octal bus transceiver

I'm using the Raspberry PI to communicate with various sensors and other circuits that input and output 5V logic level. The Raspberry Pi itself has 3.3V GPIOs, so i need to convert the logic levels. ...
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1answer
303 views

i2c over gpio - level shifter

I'm quite new to this. I have just basic background in electronics. So I would appreciate an advice from someone more experienced. I would like to connect an i2c display to my tp-link wr703n (ar9331) ...
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3answers
94 views

Looking for a level translator for single duplex serial bus

I have a 3.3V UART (two pins) plus a direction selector pin (also 3.3V.) I need to talk to and listen on a single duplex serial bus at 5V with 20 mA drive strength. The signaling rate is 3 Mbit/s, ...
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0answers
99 views

Bigger resistors in place of a level shifter on a SD reader?

This item, a MMC/SD card reader module with 3V3 LDO and 10k pull-ups, has a schematic with an interesting tidbit in a big red box: Change R3, R4, R5, R6 resistance [from 2R7] to 330-470 [ohms], ...
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1answer
104 views

Signal level shifting from +-15 to +-25

I have a bipolar signal with a peak to peak voltage of 30V (+-15V). I need to shift the signal level to be (+-25) with a dual supply voltage rails of (+-25). Do you have any ideas or a circuit ...
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2answers
1k views

Single transistor level up shifter

I need a simple, single directionnal level shifter for 3.3V -> 5V conversion. There are many options on the internet, some using a logic ic and some using 2 NPN transistors (converter and inverter), ...
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1answer
4k views

Step up 3.3V to 5V for digital I/O

I normally use an Arduino for my projects because it has 5V inputs and outputs and has 5V Vin so that makes life very easy when interfacing with 5V components. For this project I want to use a ...
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5answers
735 views

How can I switch a high-side transistor from logic referenced to ground?

Problem: I have a logic signal (represented by SW1), say from a microcontroller, that is either 0V or some low voltage, maybe 5V or 3.3V. I have a higher voltage supply (V1) and a switching device ...
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3.3V <-> 24V interface

I need to interface an ARM µC (BeagleBone Black) with a 24VDC system. 24VDC sensors and 24VDC actuators should be connected to the BeagleBone Black. I am wondered how to do this. I have found a ...
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2answers
2k views

GY-521 MPU-6050 + Arduino nano - Logic converter or not?

I bought this MPU-6050: link (marked as "GY-521" on the board) According to the manufacturers' site, the sensor logic level is 3.3V (though the eBay page says ...
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2answers
178 views

Using BSS138 in Level Switcher

I am trying to interface 1.8v UART and 3.3v UART using NXP app note here. Unfortunately, my circuit does not perform as expected. I am using BSS138 as mentioned in Adafruit and Spakrfun. When I ...
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3answers
96 views

Connecting devices with different logic levels

The following figure is taken from this link, where the author explains how NOT to connect devices having different logic levels He says that: Directly connecting the devices together (see ...
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2answers
291 views

Common Gate Level Shifter

I am in the need for a high-side load switch and came up with the following schematic. High-Side voltage levels and current vary between 5-12V / 2 A max. The high-side PMOS (SI5509DC) is rated for 20V ...
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2answers
346 views

Bidirectional Level Shifter without IC

I'd like to connect R-Pi serial to PC's RS232 port without IC (such MAX3232), using only diode (thus block negative voltage to 0V), voltage divider resistors, and common BJT. For TXD (RX from R-Pi ...
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270 views

Connecting a 3.3V circuit to a 5V bus

I would like to connect a 3.3V (not 5V-tolerant) circuit (a Xilinx XC3S200 FPGA) to a TTL-level 5V asynchronous 16-bit bus (very similar to qbus) with about 30 mostly bidirectional lines. (The bus ...
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2answers
151 views

Is a 40109 fit for 3V3 <=> 5V level shifting?

I have checked couple of datasheets for 40109 and although they specify "Supply Voltage Range" as min: 3V, max: 18V, none of the other tables specify values for < 5V. Can I safely order these ...
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2answers
267 views

How does a hex level shifter works?

My LCD screen operational pins are driven by 5V whereas my STM32 MCU outputs 3.3V maximum. I would like to shift 3.3V to 5V for about 6 pins. I could use opamps to amplify the input, but in my ...
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3answers
330 views

Use 74LCX245 level transceiver for SPI / I²C

I need to convert the levels of the SPI and I²C busses of a 5 V microntroller to a 3.3 V card reader and EEPROM memory so I chose to use the 74LCX245 since it's a bidirectional transceiver. ...
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2answers
321 views

I2C level shifting

I am currently designing a circuit that can record data from a sensor and save the data recorded into an EEPROM. My two devices (EEPROM and for testing purpose a RTC) are connected via an I2C bus to a ...
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0answers
409 views

Level shifting with BSS138 - weird values

I need to connect 5V and 3.3V devices via I2C as follows: I've connected 3.3V and 5V pull-ups and try to measure voltage. There is 5V on HV and TX_HV but 4,7V on LV / TX_LV. Putting TX to LOW ...
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Shutdown Controller for Raspberry Pi in a car

Following on from my previous question I'm trying to create a shutdown controller for my Raspberry Pi. The Raspberry Pi needs to be powered from the battery, but should power-down after the Pi ...
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1answer
144 views

newbie: comparator adjustable level shift

I'm trying to build a simple fpga logic analyser and wondering how to best design the input circuit. I would like to support 8 channels, voltage between 0-5V, with a adjustable threshold range (lets ...
7
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1answer
376 views

Open collectors & 74LVC245

I am trying to interface a PS/2 keyboard to a MSP430 for a toy. The PS/2 keyboard runs off 5V, but the MSP430 microcontroller runs off 3.3V. So I have a 74LVC245 level shifter to convert between the ...
2
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1answer
78 views

Converting logic and sign

I have an interesting project and I could use a little help. I'm using a microcontroller who's input to the ADC and output on the GPIO and DAC pins are all within a 3.3V range, and I have to interface ...
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3answers
892 views

controlling SPI devices using the Arduino - different voltages

My arduino board uses 5v to power the atmega chip. I was wondering is there any thing wrong with powering my atmega at 5v but say I power my MCP4922 dac at 3.3v does it matter? It just that I've seen ...
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2answers
2k views

Negative Voltage Level Shifting to an ADC

I am currently building a project that uses an AD595 analog devices chip to linearize the output of the Thermocouple sensor to 10mv/deg C. This output is to be connected to the ADC input of a Zigbee ...
4
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1answer
143 views

Clock conversion from 3.3v CMOS to 2.5v

I need to convert a bunch of data signals from an FPGA coming out at 3.3V CMOS into 2.5V for an LCD display. I've found the SN74CB3T16210 and the SN74AVCBH164245 and they both seem like they'll do the ...
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4answers
726 views

How to shift differential signal to read with single ended adc?

I'm using a current sense resistor (0.02 ohms) for a high current battery monitor for a hobby project. I'd like to shift this to a 0-5 V range to monitor using an ADC input (single ended.) I ...
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1answer
290 views

I2C device doesn't sink enough current

Im working on a display project and have run into some I2C issues. The display is of 3.3V design, so I figured, no big deal, ill use a level shifter and be on my merry way. Well, sure enough the level ...
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0answers
105 views

Working with arbitrary CMOS signals (2.5V - 5.5V)

I am trying to build a simple CMOS-RS232 convertor for my uC boards to be interfaced to a PC. I am using a MAX232. The board has to be able to be hooked to any uC board. I use AVR-s, ant they work at ...
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1answer
503 views

What is the difference between a voltage-level translator and a logic-level translator?

(This is a follow-up to an earlier question of mine.) I would like to use the GTL2000 bi-directional translator IC to facilitate level translation between a 3.3V circuit and a 5V circuit (including ...
5
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2answers
4k views

Solution for level-translation (3.3V Arduino Due <-> 5V shield)

The new Arduino Due board has its microcontroller running at 3.3V, but unfortunately most standard Arduino add-on shields (boards) run at 5V, thus their I/O signals are at different logic levels. The ...
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1answer
839 views

I2C level shifting and protection

I am interfacing an MCU (CC1110) with Vdd of 3.3 V to a battery gauge IC (BQ27510-G2) with Vdd of 2.5 V. Currently, I am pulling the bus up to 3.3 V with a circuit that I blindly copied from a ...