False Triggering by the TS334 in window comparator configuration

[ahari.1]

HI,

Project - Battery connected to load/charger with contactor on the positive terminal of the battery and current is monitored, whenever the current is above threshold contactor should be turned off.

Objective is to whenever the current sensor output (DHAB 118, unipolar hall effect ) crosses the threshold comparator should give microcontroller an interrupt signal indicating the short circuit current. I have configured TS334 in window comparator configuration for detecting the overcurrent, wiring diagram of how its done is shown in the image attached.

Problem being faced is comparator is giving false triggering as shown in the saleae capture.

Kindly help me in solving this issue.

Regards,

Harish

[Peter BENSCH]

Welcome, @ahari.1​, to the community!

The window comparator of the TS334 looks connected correctly, but it may be catching interference signals via its very sensitive input or via the supply voltage.

How did you connect the sensor?

Have you provided a filter, e.g. as suggested in the sensor's data sheet?

Are you using some additional filtering on VCC+ and VCC- like e.g. ferrite beads?

Regards

/Peter

[ahari.1]

Hi Peter,

Thanks for responding, Yes sensor is connected to the input of the window comparator with a filter (Fc - 1khz) and for Vcc we have only decoupling cap connected.

We will try adding ferrite beads and let you know.

Regards,

Harish

[ahari.1]

Hi,

5 V line is connected to the comparator with the ferrite bead and the low pass capacitor ( 1nF, to avoid resonant frequency) and the test was conducted, the problem remain the same - The output of the comparator goes low whenever contactor is switched ON (only during at that moment) as shown in the sampled data which is attached below. kindly help in solving this issue.

Regards,

Harish

[Peter BENSCH]

Well, you just put in a block diagram. It is not clear from this how you have wired the input of the window comparator, nor the exact wiring (line lengths, type of wiring, etc). As already mentioned, the input of the TS334 has a very high impedance, so it can easily pick up conducted or other disturbances.

Also, it is not possible to see what kind of contact is being switched. The fact that the pulse appears exactly when the contact is switched suggests inductive interference or a current pulse.

Regards

/Peter

[ahari.1]

Update - The power supply provided to the comparator was disturbed when contactor was driven which has caused the comparator output to go low.

Thanks peter for the support.

Regards,

Harish

[Peter BENSCH]

Great that it works now! You're welcome!

If the problem is solved, please mark this thread as answered by selecting Select as best, as also explained here. This will help other users find that answer faster.

Regards

/Peter