All Questions
Tagged with current-sensing operational-amplifier
27 questions
4
votes
3
answers
451
views
Sensing current down to tens of nA with INA828 or other OPA
I need to measure the current draw of DUT that can be an MCU in deep sleep, such as Attiny85, or a more power hungry MCU that is powered off by TPL5110. In this post, I proposed a circuit where an ...
- 71
0
votes
2
answers
108
views
INA828 for sensing current down to tens of nA
I need to measure the voltage drop across a test resistor in order to sense the current flowing through it. This test resistor has a value of 1 MOhm and it's connected between the positive voltage of ...
- 71
0
votes
2
answers
360
views
Designing a current sensing op-amp circuit for an AC load
I'm trying to simulate a current sensing op-amp circuit. My AC voltage, 24 VAC, is across a load of 10 Ω. I used a 100 μΩ resistor and measured the voltage across it using an op-amp.
Looking at some ...
- 1
2
votes
1
answer
542
views
Current Transformer Current Sensing via operational-amplifier
This is a current sensing circuit, L1(CT2320) is a current transformer, U1 is generated by IGBT inverter ，U is one of a three phase of the motor driver voltage. I have several questions about this ...
- 21
2
votes
4
answers
703
views
Unexpected behaviour of current sensing circuit with op-amp
I would like to use the schematic below to measure the output current of a buck converter (0-10 A) and convert it to a voltage of 0-3.3 V which is read by a microcontroller. During startup I sometimes ...
- 79
1
vote
2
answers
241
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Current Sense Amplifier / Differential Amplifier Negative Voltage On GND pin OK?
Right now I'm picking a current sense amplifier for my application, and I'm looking for for amplifiers with maximum offset voltage of below 50uV (and offset and bias currents in nA/pA range).
Luckily, ...
- 3,673
0
votes
1
answer
103
views
How do you analyze this simple circuit? [closed]
I want to plot Vout vs time graph (which software do you suggest) and also want to find out max and min output voltage (Vout) of the circuit. How can I find the max and min manually?
Can I find them ...
- 11
0
votes
2
answers
140
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non-inverting current sense op amp output unstable during the measurement
I would like some advice on how to solve the following problem. The following circuit is motor driver with current sense circuit. The circuit run motor at cca 30mV when is not under load, but when the ...
- 71
1
vote
1
answer
403
views
Dedicated current sense amplifier vs simp,e difference amplifier
I need to implement low-side current sensing for a H-bridge motor driver. While there are dedicated current sense amplifiers such as TI’s INA180, can I use a simple difference amplifier for this with ...
- 1,360
1
vote
1
answer
382
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 ...
- 6,064
0
votes
1
answer
288
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 ...
- 43
2
votes
2
answers
867
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 ...
- 866
0
votes
1
answer
148
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 ...
- 1
1
vote
1
answer
695
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 ...
- 924
1
vote
1
answer
56
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 ...
- 121
0
votes
1
answer
75
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 ...
- 121
0
votes
3
answers
694
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 ...
-2
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1
answer
93
views
0
votes
2
answers
412
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Overcurrent Sensing
I am designing an overcurrent protection circuit. I am sensing current with a LEM sensor across a sensing resistor of 16.5 ohm. The voltage drop for maximum current is 2 V. In the next stage I am ...
- 165
0
votes
0
answers
254
views
High side current sensing in BLDC motor?
I want to measure DC current flow through the 48 V battery in bldc motor (through Inverter circuit). Are INA 282, INA 169 work properly or not? Since my battery motor specification is 48 V, 5 Amp, 250 ...
- 79
1
vote
2
answers
708
views
Differential amplifier for current measurement
I'm studying reference design from TI (pdf).This design shows the solenoid control circuit. I was interested, why a differential amplifier is used to measure the current? Why not use non-inverting ...
- 470
1
vote
1
answer
175
views
Common mode error formula from TI seems counter intuitive
I'm working on an application to measure current in a buck converter using a current sense amplifier. According to this video from Texas instriment, the equation for common mode error is same as eqn 1 ...
- 11
1
vote
2
answers
1k
views
Current sensing with Rdson?
I'm fooling around with a PMOS, a Fairchild FDD6637, and pondering whether it would be possible to use Rdson as a sort of shunt-resistance for measuring the voltage drop, to get the amount of current ...
- 980
3
votes
1
answer
1k
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Automatic ranging current sensing
I am trying to implement a current shunt sensing circuit. This should be automatic and currently i want it to measure uA to around 200mA, and Change to the mA range at around 200uA. This is to profile ...
- 231
1
vote
1
answer
2k
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Unipolar Hall current sensor signal conditioning for 5v ADC
Need help. I need to convert signal (0v to 5v) from Hall-based unipolar current sensor measuring the power line from the 84v 4kW battery pack to 5v MCU based ADC converter. Although both – the sensor ...
- 364
3
votes
2
answers
4k
views
Transimpedance vs. Non-Inverting Amp for high sensitivity application
In simple analysis, these two circuits give the same result ... i.e. producing 1V output for a 10pA input. Is there any advantage of one over the other in practice?
I am measuring currents in the ...
- 183
4
votes
3
answers
3k
views
Op amp with transistor in feedback
I am currently looking for a high side current sense IC. I have noticed that most of them that are without galvanic separation, are using an op amp with bjt transistor like in bellow schematics:
The ...
- 1,699