TMCS1133: Sensors forum

Chaithanya Nagirimadugu

Part Number: TMCS1133

Hi Team,
Greetings of the Day!

We are evaluating TMCS1133B1A (Hall-effect Current Sensor), which has a Signal bandwidth of 1 MHz.

Now we are testing the input-to-output response at 150KHz frequency, which is less than the rated bandwidth. Here we are getting a typical response of nearly 1.6usec, between the input to output waveforms.

Here we are sharing the testing observations. Pls verify these and share your suggestion to improve the response time.

DSO Image:

Yellow: Current sensor input (50mV/A), Dark_Blue: Current sensor output.

Practical Observations:

Current sensor input = 16A Peak (32A p-p).

Current sensor output = 20A Peak (40A p-p).

Thank You in advance!

Regards,

Chaithanya.

8 months ago

0 Mitch M 8 months ago

TI__Mastermind 21745 points

Hey Chaithanya,

From your scope shot, I am not seeing where you got the 1.6µs delay from. Also, can you double check your setup to make sure the scope probes were not swapped? To me it looks like yellow is the output and blue is the input.

Regards,

Mitch

0 Chaithanya Nagirimadugu 8 months ago in reply to Mitch M

Prodigy 160 points

Hi Mitch,

Thanks for the reply!

Mitch M said:
Also, can you double check your setup to make sure the scope probes were not swapped? To me it looks like yellow is the output and blue is the input.

We have checked our set up and scope probes were not swapped.

We have tested TMCS1133B1A (Hall-effect Current Sensor) at 150KHz, 250KHz and 350KHz frequency. Unfortunately we are facing an issue as mentioned in below.

1. DSO image shows sine waveform at Sensor input, but Sensor output (TMCS1133) is not at close to input. Now my question is Why Current waveform shape is not sine and also noisy?

Here we are sharing the testing observations with test set up diagram. Pls verify these and give your support/suggestions to overcome this?

TMCS1133_CT_Test_Results.xlsx

PMCS1133_CTsensor_testing results.docx

Regards,

Chaithanya N.

0 Mitch M 8 months ago in reply to Chaithanya Nagirimadugu

TI__Mastermind 21745 points

Hello Chaithanya,

I am reviewing the data you sent, and will get back to you on Monday.

Regards,

Mitch

0 Chaithanya Nagirimadugu 8 months ago in reply to Mitch M

Prodigy 160 points

Hi Mitch,

Thanks for the reply!

We will wait for your response.

Regards,

Chaithanya N.

0 Mitch M 8 months ago in reply to Chaithanya Nagirimadugu

TI__Mastermind 21745 points

Hello Chaithanya,

I have reviewed the data, but nothing stands out to me so far. Can you please send a snip of the schematic section around the TMCS1133?

Also, to help validate the setup, could you follow the instructions from section 4.2 (Advanced Measurement Tips) of the EVM user's guide: https://www.ti.com/lit/pdf/sbau421

Regards,

Mitch

0 Chaithanya Nagirimadugu 8 months ago in reply to Mitch M

Prodigy 160 points

Hello Mitch,

Here I am sharing the paper schematic of TMCS1133. Please Review it and add your suggestions.

Regards,

Chaithanya N.

0 Mitch M 8 months ago in reply to Chaithanya Nagirimadugu

TI__Mastermind 21745 points

Hello Chaithanya,

This schematic looks fine to me.

Sorry, I just realized I had the wrong link in my previous message. I have corrected the link now. Please let me know when you have been able to do the test from section 4.2. Using a precision shunt resistor to verify can be very helpful.

Regards,

Mitch

0 Mitch M 8 months ago in reply to Mitch M

TI__Mastermind 21745 points

It would also be good to make sure that the GND of the TMCS1133 and the scope are both stable and not ringing.

0 Mitch M 8 months ago in reply to Mitch M

TI__Mastermind 21745 points

You could also get a TMCS1133BEVM and connect it to your system to help rule out hardware/layout issues. You would still need to make sure the GND is connected well to the EVM and is not the cause of the errors.

0 Chaithanya Nagirimadugu 8 months ago in reply to Mitch M

Prodigy 160 points

Hi Mitch,

We are using a standard DC source which is isolated from everything. DSO probe ground clip is connected to just 1133 ground - Except HALL probe (yellow color image), NO other probe is connected.

1. At 150Khz: Why the shape of pink color (1133 output) is not following sine (yellow is HALL probe of DSO).Pink color is not a proper sine wave. What is causing that difference.

2. At 250K and 350KHz: There is lot of noise on pink (1133 output). What shall be done to reduce noise? RC filter?

PMCS1133_CTsensor_testing results.docx

Regards,

Chaithanya N.

0 Mitch M 8 months ago in reply to Chaithanya Nagirimadugu

TI__Mastermind 21745 points

Hello Chaithanya,

Here are my responses to your questions:

1. I can't speak much for the Hall probe, so it's hard to say why they would be different. That's why I recommended verifying with a precision shunt and/or the EVM.

2. If there is more current noise than you prefer, then you can add an RC filter. However it looks like the noise is present to some degree in both signals, so it may be better to find the source of the noise and reduce that if possible.

Regards,

Mitch

0 Chaithanya Nagirimadugu 8 months ago in reply to Mitch M

Prodigy 160 points

Hi Mitch,

Thanks for the reply.

We will buy EVM and verify it with our set up.

Regards,

Chaithanya N.