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DRV5033: Questions about Bop, Brp, and Bhys

Annie Liu
Genius 10295 points
Part Number: DRV5033

Hi team,

The customer is experiencing below issue and needs your help.

On the sixth page of the manual,

Bop

MIN=±1.8mT TYP=±3.5mT, MAX=±6.8mT.

Brp

MIN=±0.5mT TYP=±2mT, MAX=±4.2mT.

Question:

1. What is the approximate distribution ratio of the above-mentioned MIN\TYP＼MAX in mass production?

2. Is it necessary to ensure that when the magnet is close to DRV5033, the magnetic field strength is >6.8mT to ensure that the reliable output of the entire batch of products is 0V？

3.Is it necessary to ensure that the magnetic field strength is less than 0.5mT when the magnet is far away from DRV5033, in order to ensure the reliable output high level of the entire batch of products is +5V (with a pull-up resistor 10kΩ to 5V);？

4. Are the values of Bop, Brp, and Bhys fixed when the chip leaves the factory? Or is it adaptive based on the actual magnetic field strength from the magnet to the chip? For example, if the current magnetic field strength from the magnet to the chip is 5mT, what is the magnetic field strength for the chip to read and record?

5. How to understand Bhys=±1.5mT? If the difference between Bop and Brp>1.5mT, then the chip can reliably output 0V and 5V (with pull-up resistor 10kΩ to 5V)？

Thanks,

Annie

  • 0
    TI__Expert 3665 points

    Hi Annie,

    Thanks for reaching out, see my feedback below, looks like you are using DRV5033FA version. We have a great video that describes all of the magnetic specifications in detail that i think will be very helpful for you here:

    https://training.ti.com/ti-precision-labs-magnetic-sensors-latches-switches-operating-release-point?context=1139747-1139746-1137749-1139634-1137743

    1. What is the approximate distribution ratio of the above-mentioned MIN\TYP＼MAX in mass production?

    • Ill check internally, not sure what this may be.

    2. Is it necessary to ensure that when the magnet is close to DRV5033, the magnetic field strength is >6.8mT to ensure that the reliable output of the entire batch of products is 0V？

    • Yes , this is correct. Max Bop trim on this IC is +/-6.8mT. 

    3.Is it necessary to ensure that the magnetic field strength is less than 0.5mT when the magnet is far away from DRV5033, in order to ensure the reliable output high level of the entire batch of products is +5V (with a pull-up resistor 10kΩ to 5V);？

    • Yes this is correct as well.

    4. Are the values of Bop, Brp, and Bhys fixed when the chip leaves the factory? Or is it adaptive based on the actual magnetic field strength from the magnet to the chip? For example, if the current magnetic field strength from the magnet to the chip is 5mT, what is the magnetic field strength for the chip to read and record?

    • No these thresholds are fixed.

    5. How to understand Bhys=±1.5mT? If the difference between Bop and Brp>1.5mT, then the chip can reliably output 0V and 5V (with pull-up resistor 10kΩ to 5V)？

    • Bhys = Bop - Brp, No the must be above the Bop or below Brp to reliably output oV or 5V. Over temperature you must consider the Bop/Brp max and min ranges.
  • 0 in reply to Julio Apps
    TI__Genius 10295 points

    Hi

    The customer's application is HALL proximity switch. He has further questions and needs your help.

    1. Does DRV5033 and magnet position design need to meet:

    • When the magnet is close to the chip, the magnetic field strength on the chip must be greater than 6.8mT for the chip to reliably output low level
    • When the magnet is far away from the chip, the magnetic field strength must be less than 0.5mT, so that the chip can reliably output high impedance state (connected with a pull-up 10k resistor, the output becomes 5V reliably)

    2. For a specific DRV5033 chip (has been made into a finished HALL proximity switch), the maximum magnetic field strength when the actual test magnet approaches the chip = 4mT, and the minimum magnetic field strength when the magnet is far away from the chip is equal to 1mT. The actual output waveform of DRV5033 tested with an oscilloscope is

    • The voltage is 0V when the magnet is close to the chip
    • When the magnet is far away from the chip, the voltage is 5V

    So does the DRV5033 of this particular finished switch keep the magnet close to the chip and output 5V for the next 5 years?

    3. For the fifth question above, customer's understanding is:

    • In order to reliably output low level 0V, the magnetic field strength must be greater than the Bop (a value of 1.8mT to 6.8mT) of the current chip (the factory-made chip) when the magnet approaches the chip
    • In order to reliably output high levels, when the magnet is far away from the chip, the magnetic field strength must be less than the Brp of the current chip (the chip has been shipped) (a value from 0.5mT to 4.2mt)

    And the Bhys=Bop-Brp of each chip after leaving the factory is a fixed value, that is 1.5mT (Type value). Temperature will affect the Bop and Brp values of the chip. Is this understanding correct? 

    Thanks,

    Annie

  • 0 in reply to Annie Liu
    TI__Expert 3665 points

    1. Yes, that is correct.

    2.This looks correct for this one specific IC, you may have received one that is close to the typical specification where the Bop is 3.5mT and Brp is 2mT. This does not guarantee that it will work over temperature nor with other same devices as it is possible that the thresholds for another part may be different but within the given Max and Min in the datasheet. So no we cannot guarantee that the one device will give you a reliable output over time. You have to be above and below the max/min Bop/Brp operating thresholds given in the datasheet.

    3. No, to reliably output low level with any device that is shipped to your customer the magnetic field strength must be greater than +/-6.8mT. To output high level for any device that is shipped to your customer, the Brp must be less than +/-0.5mT.

  • 0 in reply to Julio Apps
    TI__Genius 10295 points

    Hi

    Customer has further questions and needs your help.

    1. Connect Vcc to 5V, connect Vout to pull-up resistor to 24V

    2. When the magnet is close to the chip, the output pin of the chip is low. The sink current Isink of 24V through the pull-up resistor to the Vout pin of DRV5033 is 7mA.

    3. When the magnet is far away from the chip, the output pin of the chip is high and suitable for 24V

    Customer would like to know will the above application cause the chip to malfunction?

    Thanks,

    Annie

  • 0 in reply to Annie Liu
    TI__Genius 15250 points

    Annie,

    Vout and Vcc should be fine operating at these voltages.  The requirement here is that both voltages stay within the ABS max rating in the datasheet.  Both pins are rated to a maximum of 40 V and are independent.

    The output pin typical recommended operating conditions shows that the device is capable of sinking 30 mA, so the 7mA through the pull-up is fine.

    Thanks,

    Scott