TLE5041plusC Rm range

[WuXiaoyun]

Hello, the Rm given in the TLE5041plusC datasheet is 30Ω-75Ω, is this the corresponding value in the case of a supply voltage of 4.5V? If the power supply voltage is set to 15V and the Rm is 470Ω, will there be any problems when using the IC?
Or what is the minimum and maximum value of Rm when the supply voltage is 15V?

[Yashraj_P]

Hi @WuXiaoyun ,

The Rm should be within the range 30-75 Ohms, as specified in the datasheet, if Vdd is within the operating range of 4.5-20 V. 

Thanks and regards,
Yashraj

[WuXiaoyun]

Hi Yashraj

What is the effect if Rm exceeds 75 Ohms (using 470 Ohms)?

[Yashraj_P · Accepted solution]

Hi @WuXiaoyun ,

For Rm= 470 Ohms, the power on time and slew rate may increase too much to make proper edge detection.
Why do you require such high Rm?

Thanks and regards 
Yashraj

[WuXiaoyun]

The IC that the customer used before was NXP's KMI15_2. Since this IC from NXP has been discontinued, we need our help to find a replacement product. The customer requested that the Rm should be 470 Ohms during product testing, and no IC that fully meets this requirement has been found yet.
If you want to replace KMI15_2, which model IC from Infineon do you recommend?
Attached is NXP's KMI15_2 datasheet.

[Yashraj_P]

Hi @WuXiaoyun ,

In principle, you can use the 470 Ohm with TLE5041PlusC, but it is not recommended by Infineon. The discussed boundary restrictions need to be taken into account, as mentioned.

Is there a need to use GMR or Hall sensor can be used? What is the use case application?

Best regards,
Yashraj

[WuXiaoyun]

Hi Yashraj

It is used to detect the speed of subway train wheels. The specific application method is as follows: install a magnetic encoder wheel on the shaft end of the subway wheel shaft (Figure 1, the surface of the magnetic coil is evenly distributed with 100 pairs of magnetic poles), the IC is packaged inside the metal shell, and the installation On the upper part of the magnetic encoder wheel (Figure 2), when the magnetic encoder wheel rotates with the wheel, the IC detects the speed of the magnetic encoder wheel and outputs a frequency signal (current type 7/14mA), the IC is only used for speed detection, the magnetic encoder wheel The direction of rotation does not need to be detected.

[Yashraj_P]

Hi @WuXiaoyun ,

If there is no particular requirement for GMR based sensor. For your application, the TLE4941PlusC which is Hall based, could serve as the replacement speed sensor. As far as the fields are not too small, which depends on the airgap and the pole-wheel pitch.

Thanks and best regards,
Yashraj

[WuXiaoyun]

Hi Yashraj

The surface magnetic field strength of the magnetic encoder wheel is 32±3mT, and the distance from the IC surface to the surface of the magnetic encoder wheel is 3.5±0.5mm.
Is it installed with the front (marked 41CPA) facing the magnetic encoder wheel surface (Figure 3)?

[Yashraj_P]

Hi @WuXiaoyun ,

The mentioned specifications of magnetic encoder wheel are within the range. You could go ahead with the application tests.

I think following image would help in identifying the front side.

If you still have questions, you could send close up pictures of both sides of the sensor.

Thanks and kind regards,
Yashraj

[WuXiaoyun]

Hi Yashraj

Is the front side or back side of the TLE4941PlusC facing the magnetic encoder wheel?

[Yashraj_P]

Hi @WuXiaoyun ,

As mentioned in the datasheet, the front side of the sensor package is facing the magnetic encoder wheel. Please go through Section 2 of Datasheet describing Functional description of the sensor.

Thanks and kind regards,
Yashraj