Questions tagged [current-sensing]

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36 views

INA219 current sensor not working properly with DC motor

I use INA219 module to read DC motor current for control propose. I connect INA219 in series with motor as shown in schematic. simulate this circuit – Schematic created using CircuitLab The ...
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1answer
58 views

Current Sense circuit with digitally programmable gain

I'm designing a precision source meter and I wanted to put a couple ideas out to the community. One thing I will note is that this device has 32 channels, so I need to be very cognizant about both ...
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50 views

How to average output of current sensor to get smooth output?

I am using INA138 current sensor with 100Hz, PWM duty 5%, 8-bit resolution signal load is a resistor, I getting zero readings while actual current readings also appear, edited - zero current sense ...
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21 views

Designing high bandwidth current sensors for inductor current sensing

I am designing a high-frequency current sensor, suitable for sensing +/- 20 Amps at frequencies of 200kHz. This is being used in average current mode control application in an isolated forward ...
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1answer
43 views

Low Side Current Sensing Grounding Question

I recently made a low side current sense circuit to test a power supply. It works well, but I am trying to understand the strange behavior that happens when I apply the negative lead of my probe to ...
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1answer
44 views

Microamp-milliamp Measuring Circuit: will my circuit work? Feedback/Advice

I'm developing a device which must be able to measure milliamps and microamps on one of its lines (down to 1 microamp, but also clearly seeing if it's less than 1uA). It's going to be DC of different ...
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2answers
45 views

Converting a 4-20mA 24V signal to 0-5V?

How do I convert a 4-20mA 24V signal to a 0-5V signal, suitable for A-D conversion with a 5V microprocessor? Can this be done while isolating the 24V from the 5V output?
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0answers
22 views

Detect Battery Insertion in USB Charging Circuit

I'm using an MCP73831T as the charger IC, I've figured out how to detect the charging/charged, this was easy, however, I would like to know when the battery is actually plugged in, I know when the usb ...
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1answer
132 views

Current sense op-amp with integrated shunt vs expensive resistor

To simplify my question lets assume: I need to convert +/-7.07A RMS AC current into +/-707mV RMS voltage with high acurracy (0.1% or better). It may be also higher voltage, up to +/-2.5Vpk. For now ...
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1answer
33 views

How to sense current AC of a sinusoide -100mA to 100mA with 70kHz

Any suggestions about a chip or PCB component that could work? I tried to use the the current sense transformer PA1005.050NLT https://www.digikey.com/product-detail/en/pulse-electronics-power/PA1005....
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1answer
66 views

Current Sense Amplifier Potentials

I'm trying to implement a current sense amplifier in my application, but I have a question about setting it up with regards to current flow. Basically, in this case, you put a very small shunt ...
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3answers
92 views

Current Sensing on positive and negative voltage rails

I'm working on a design that uses two separate buck regulators to generate a positive and negative voltage, and I'm trying to implement current limiting with a current sensor. However, I am running ...
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2answers
79 views

I am looking for a 40 input OR gate which minimize PCB space

I am using 40x ICs INA301 to measure overcurrent in 40 interfaces Finally I want to have 1 single "output" to signal if there is an overcurrent in ANY of the 40 interfaces I don't want to utilize any ...
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4answers
83 views

Charge indicator with comparator - very sensitive to noise

I need an indicator when the current from my charger is larger than 100mA. I tried the below circuit but this seems very sensitivity to noise. Probably I am getting some ripple in the mV range from ...
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1answer
65 views

Reading registers from ACS71020 over SPI

I'm trying to read registers from current-sensing chip ACS71020 connected over SPI. This is how I initialize the SPI: ...
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2answers
46 views

AC phase current sensing using Isolated delta-sigma modulator

I am trying to design a isolated AC current sensor. I've chosen the AMC1106 Isolated Delta-Sigma Modulator. (change my mind if you think there is a better solution for 220V AC; 2A Max; 0.25%) The ...
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22 views

Dual channel current sense circuit design

First of all if this isn't the correct place for a post such as this please tell me where I should post it. I need a circuit that will allow me to measure the current of two solenoid operated pump ...
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0answers
23 views

Load sensing relay/power switch/adapter which switches on when it detects some load on its input

Complete newbie here. I'm not using the right terms, so my apologies in advance. The problem is simple. I want my powered computer speakers (2.1) to turn off when the computer is turned off. I have ...
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1answer
39 views

Method for sensing fault currents with microcontroller

How do I choose a proper approach for detecting ground fault currents (20 mA through 30A, 60Hz)? Let's say I have a zero sequence CT and calculate a burden resistor. I have a 12-bit ADC in the micro. ...
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1answer
61 views

Measuring AC Current at High Voltages (up to 600VAC)

I've been looking at various ways to measure current for a while now, and am stumped on how to read high-side AC Current Measurements ohmically (no Hall Effect sensors). My initial thought was to use ...
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1answer
65 views

op-amp level shifter

I'm working on a brushed dc motor driver and I have to monitor the current. so I use ACHS-7121 current sensor. This sensor convert +-10A into 0V to +5V and have +2.5V in zero current. Now I want to ...
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1answer
89 views

Current Sensing with Op-Amp, do I need a shunt resistor in series with the load on the output?

Hi I am building a circuit to measure current draw from a load, I opted for a voltage follower with a transistor and a shunt in between, The transistor is needed to allow higher currents to flow ...
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1answer
140 views

Current sensing relay with delay on break for dust collection system

I am in the process of planning our a new workshop in a single car garage. I have a large 20A Dust Collector that needs to be on its own circuit or else it will trip. I also have a ceiling mounted ...
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3answers
249 views

Detecting switch closure

Any techniques/circuits/sensors that can determine the open/closed state of a set of contacts, independently of whatever power or signals are being switched by the contacts? Obviously easy if there's ...
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1answer
46 views

Output current and voltage levels regulation in ac/dc adapter

On the picture below is the output circuit of AC/DC adapter. I understand how voltage level contol works, but I don't understand how exactly current limitation works and how should I calculate ...
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1answer
126 views

High voltage and cheap differential amplifier

Can I use a LM324N (very common) op-amp to act as a high-side differential current sense op amp at high voltage? The Differential Amplifier The differential input voltage rating is 32v, but my load ...
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0answers
172 views

Problem writing to EEPROM in Allegro ACS71020 through SPI

I can't write all the EEPROM registries in the ACS71020. Before every writing I write the unlock code to 0x2F. Only the first writing takes place (register 0x0B), the others do not. In the datasheet ...
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1answer
29 views

Current monitor output doesn't respond to load changes

When I physically build this circuit the output voltage doesn't response to load variation. The voltage across the sense resistor is definitely increasing when decrease the load resistance, the ...
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1answer
64 views

Measuring high currents with toroids

I got a PT27312 current sensor (datasheet), I wonder if I can use it to measure currents up to 100A AC/DC. I couldn't find any specifications in respect of the current measurement range. I only know ...
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0answers
34 views

current remote sensing behind barriers

I'm trying to determine where a fault in a wire is located. The wire(s) are typically behind panels or other barrier which I want to avoid opening. I am considering detecting temperature changes (...
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1answer
35 views

Working Voltage for Basic/Reinforced Isolation (ACS712)

I'm planing to use current sense chip ACS712. I don't understand some values in its datasheet, page 2 (Isolation Characteristics). I understand "Dielectric Strength Test Voltage - 2100VAC" - that ...
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2answers
101 views

“ground disturbance” in current sensing with shunt resistor

There are lots of questions about "traditional" low-side current sensing using a shunt resistor. Most discussions and papers mention the drawback of "ground disturbance" introduced by the measurement ...
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1answer
36 views

XADC Current Sensing Reference Design

Please refer to this reference design for AC701 (snippet below). The schematics, specifically the current sensing sections in pages 34-36, show this: I want to understand why, for the REF output of ...
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2answers
157 views

How to connect multiple sensors to single PLC input?

Hello. I have a scenario where I have multiple PNP "error signal" from several sensors (let's assume 3 for now). If the sensor output is HIGH, then there is error. If the sensor output is LOW, then ...
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8answers
7k views

What is negative current?

I understand that voltage is relative to ground, so that can be negative. However, I'm currently looking at current-sensors (ACS712 current sensor) and in the performance characteristics table, it ...
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1answer
47 views

Current transducer - understanding of turns ratio connection

I'm using a LEM LAH 25-NP current sensor and I don't understand the recommended PCB connections in the table from the datasheet. I understand the first one, but what is with the second and third? What ...
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1answer
38 views

Current sensing using XADC

AC701 Schematics Refer page 40 of the schematics. Here for Vccint- the regulator is switching at 250 kHz. page 34 has the sensing signal conditioning for that the inst. amp used is INA333 which ...
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2answers
90 views

Current Sensing Amplifier Circuit explained

I've been trying to understand why each every comment is in the circuit shown. I understand that the amp is taking the voltage drop across the Rsense and amplifying it such that the current across it ...
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3answers
158 views

INA168 vs INA169 High-side current sensing

I have read the datasheets of the INA168 and the INA169 and can't see any difference, other than internal resistors value and quiscent current (25uA for INA168, 60uA for INA169). Those two were even ...
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2answers
57 views

Sensing Voltage and Current of an Adjustable Voltage Source

I am currently working on an Adjustable Voltage Source, the Voltage Source is built by a voltage regulator with an OpAmp with and a Darlington transistor for current amplifying as the following ...
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0answers
68 views

Current sense trace vias underneath shunt resistor

I need to connect current sense traces from a shunt resistor to my PMIC on the other side of the board. Due to space constraints, I'd like the traces to pass through vias directly underneath the shunt ...
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3answers
371 views

2000A current sensing using STM32

Is there any chance to read 2000A using STM32? I searched the Internet for low-value shunt resistor but nothing found. maybe some kind of current transformer could do the job!! any help will be ...
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0answers
39 views

Buck converter design using MCP1630V

I have already designed a buck converter with the following specifications using an MCP19035: Vin=14V, Vout=1.8V, Fc=63kHz(Crossover frequency), Vref=0.6V, Iout=10A step load High IOH=7.5A step ...
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0answers
37 views

Using a switching DC-DC converter in high dynamic range current/voltage sensing

I'm thinking of making a power meter circuit which will have a high-side current-sensing amp (LTC6102), a resistive voltage divider for sensing the voltage, a dual op-amp (OPA2365) as a buffer for the ...
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0answers
73 views

H-Bridge Low Side Sense Resistor - Position of Resistor and Bulk Capacitance

My question regards the considerations required in determining the location of a current sense resistor on the low-side of an H-Bridge. I've presented two scenarios. Details: The H-Bridge load is a ...
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1answer
3k views

ESP32 using acs712 give wrong values

I'm trying to measure current with acs712 30A current sensor connecting to NodeMCU-32S but I'm getting wrong and unstable values. For zero current the ADC pin should read value of 2048 (esp has 12 bit ...
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1answer
73 views

0-20mA to voltage conversion. Is this circuit OK?

Is this circuit OK, in your opinion?
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1answer
338 views

FOC sensor vs sensorless

I am trying to understand the hardware difference between the sensored and sensorless FOC 3-phase Induction Motor Drive circuit. So far what I understand is that FOC require following sensors: 1. ...
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1answer
163 views

SMPS Current Sense Resistor Selection

I am looking into using an SPV1040 boost converter to charge a battery from a solar cell. The chip includes inputs for a current sense resistor, which are described in one of ST's applications notes ...
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1answer
539 views

Shunt resistors and PCB layout

I have several questions about the current sensing through a resistance. The resistances are 2-SMD package and I will use the 4-wire kelvin method for the layout.(see image) Specifically, there are ...