INA240: ina240

Hello Robert,

The output response represents the behavior of a typical solenoid driven with PWM waveform.

From the moment driving signal is applied till about 5mS, the solenoid plunger is stationary; at 5mS, the plunger starts to move and stops at about 12mS.

All solenoids will have similar response curve, even though the plunger travel time and current level is different.

Regard, Guang

Apps Support-Current Sensing

Hi, thank you for your answer. But I don't understand one thing. Below the voltage measured across a 3.3ohm shunt resistor that is in series with a solenoid(electrovalve) and drived with a  high side 24V mosfet; even if my differential inputs go high fast (so they have to reflect also the current in the solenoid divided by 3.3ohm), the output of INA240 is delayed(blue one) Why this behavour? thank you.

Hello Robert,

What are the Yellow and Purple traces, the positive and negative input pin voltages? I don’t see differential input, and can’t tell that it is going high fast.

The differential input is the difference between the yellow and purple, assuming that they are the P and N input voltage of course.

Regard, Guang

Apps Support-Current Sensing

Hi,

Yes they represent the positive and negative voltage at the input. So their difference represent the differential voltage across a 3.3ohm shunt resistor, in a high side current monitor configuration where an electrovalve is the load to monitor. Since the output of the part is delayed of about 20ms before reaching the wanted value , i don't understand if this behaviour is due to electrovalve current( but in this case the difference between the input voltage divided by 3.3ohm should represent this current so they should be also delayed) or if this is due to the ina139 response to high common mode  voltage transient or range..

Thank you.

Hello Robert,

Have you plotted the differential input? What the scope shot shows are common mode inputs, not differential.

To see the differential input, you need to use the math “minus” function of the scope. Once you do that, you’ll see that the INA output is a faithful, amplified, version of the input differential voltage.

Regard, Guang