TMAG3001: Question about TMAG3001

Hi Frank,

Thank you for posting to the Sensors forum!

For this device, the sampling frequency in determined by the configuration of the CONV_AVG bits.

The TMAG3001 is a 3D hall-effect sensor which allows for it to monitor the magnetic field in the X, Y, and/or Z direction based on the selected configuration of the MAG_CH_EN bits in SENSOR_CONFIG_1. 

We also have a magnetic simulator that customers can use to help simulate their designs called TIMSS: https://webench.ti.com/timss/  

Best,

~Alicia

Hi Alicia,

Thanks for the comments.

• Could you please help to comments, under what sampling frequency for the following Iactive & Istandby measurement? Does frequency influence these current?

• If we set both upper/lower threshold for 3-axis[x,y,z]. Will it function at the same time? It means, if any two threshold or even more threshold are triggered, will it generate more interrupts?
• 
• What is the angle accuracy for angle calculation? It means, if we read the the register to get the angle=10°, the accuracy will be like 10°+/-?%
• Can we use /INT pin for SCL application?

BR.

Frank

Hi Frank,

Regarding the spec for Istandby, this is for when the device is in standby mode with no conversions started, so there would be no sampling in this scenario. Regarding the impact that the sampling frequency may have on the current when in continuous conversion mode, I will need to check with my team on that and will provide a response shortly.

If you set a threshold for one or more axes, the device will check for a threshold cross for all of the set thresholds, assuming the relevant axes are enabled. To help clarify, an interrupt will be asserted as soon as at least one of the interrupt conditions has been met.

Regarding the angle accuracy, please see the snippet below from section 5.7 Magnetic Characteristics for A1 of the data sheet

Regarding whether or not you can use the INTB pin for SCL applications, could you please clarify what you mean by this? Are you trying to use this pin as some kind of clock? If so, I do not believe that the INTB pin can be used in such a way.

Best,

~Alicia

Hi Alicia, 

Thanks for the comment.

Please double check the test condition with IACTIVE(especially on which sampling frequency)

• For 360 degree measurement, do you have some document which can explain more detailed on how TMAG3001 setup or TMAG3001 application on 360 measurement?

BR.

Frank 

Hi Frank,

The team is out for the labor day holiday. They should be able to take a look at your post when they come back tomorrow.

Regards,

Mekre

Hi Frank,

I am still looking into the test condition for Iactive regarding the sampling frequency, apologies for the delay.

Regarding your question below:

Frank Cai said:

For 360 degree measurement, do you have some document which can explain more detailed on how TMAG3001 setup or TMAG3001 application on 360 measurement?

Could you please clarify or rephrase the question? I am not sure I understand what is being asked here.

Best,

~Alicia

Hi Alicia,

Do you already check the sampling frequency with both IACTIVE,ISTANDBY and also the angle measurement which shows in DS?

Customer is wondering if we could provide some document which describe how we setup TMAG3001 for 360 degree measurement. They are not familiar with 360 degree measurement setup so they want to learn about it.

BR.

Frank

Hi Alicia,

For 360 degree measurement, for example, are there any requirements on magnet strength, magnet size and distance between TMAG3001 and magnet?

Can you also provide TMAG3001 3D model for PCB layout?

Thanks

Frank

Hi Alicia,

Thanks for the detailed comment.

Could you help to clarify, whether different sampling frequency does influence on angle error?

Thanks

Frank

Hi Alicia,

Thanks for the comments.

Our competitor is AK09973D which has much smaller power consumption compare with TMAG3001 in standby mode, could you help to check the following device and DS and figure if we really have worse performance on power consumption on stand-by mode?

If 450uA is the standby mode power consumption, I am afraid that the smartwatch cannot use TMAG3001 since their battery is only about 500-600mAh.

https://www.semiee.com/file2/41f26b800ac857109a08887646eda033/AKM/AKM-AK09973D.pdf

Sincerely

Frank

Hi Alicia,

Btw, for switching frequency f=100Hz and f=300Hz, is the power consumption very close for TMAG3001?

From customer description, competitor device has  difference when the frequency is different, just want to double check with you. Thanks.

BR.

Frank

Hi Frank,

Frank Cai said:

Btw, for switching frequency f=100Hz and f=300Hz

This sampling rate is more comparable to this device's W&S mode. So comparing this level of current consumption to this devices continuous conversion mode would not really be comparable. The 'closest' update rate would be if all 3 channels enabled at 32x averaging at 400Hz, as shown in the table below. But even in this scenario, the device is sampling and then averaging 32 samples for the X, Y, and Z, which would explain the higher current consumption when compared to the competitor, which is not doing that much. 

I would recommend using W&S mode and configuring the sleeptime to 10ms as this would give a sampling rate of 100Hz and be more on par with the competitor.

Best,

~Alicia

Hi Alicia,

I think W&S mode is the best choice for customer.

Could you please help to provide the EVM power consumption test on the following conditions by today? Customer needs the data to have a comparison with competitor, so that they can keep TMAG3001 evaluation on-going. They want to double check with BU about their measurement. Currently they measure the power consumption is about 100 uA.

Conditions:

LP_LN=0h;

VCC=1.8V

Conversion time=600us, for 3 channel enable.

Sampling frequency=100Hz, 50Hz, and 10Hz.

Thanks for your great support.

Sincerely

Frank