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INA240: Plunger detection sensing query

Part Number: INA240
Other Parts Discussed in Thread: DRV110

Hi

If i am u sing the IC INA 240 for the solenoid plunger movement detection, how we will come to know

1. If the solenoid plunger is fully open/ fully closed?

2 .if any plunger moving very slow due to any faulty ,how will come to know.

and usually I saw some of the analog circuits will have an integrated amplifier, active peak detector, op-amp adder and a comparator to know the check the IPEAK and Ivalley and finally comparator output will take to ADC,but here how i will come to know my requirement which i mentioned above?

Regards,

shishod

  • shishod,

    Check out TIDA-00289. While this design is centered around DRV110, there is an example of the circuit you mention, and this TI design provides some walk through of solenoid characterization and how to characterize your solenoid's current curve, as well as how to process the data.

    To answer your questions,

    1. when the solenoid is faulty or the plunger has not moved fully, the solenoid current either does not have a dip or a dip of sufficient magnitude to cross the predefined threshold of the comparator circuit you mention. This result is interpreted as a fault condition. Section 4.2.4 of this TIDA provides a lot of information as well as a schematic example of this type application.

    2. To do this, you would need to come up with a circuit (or instructions in logic) to capture the time of the peak voltage, as well as the valley voltage, as these points in the curve represent the start and end of mechanical movement. Deviation of the delta between these two points would dictate that the coil movement is beginning to slow.