infineon4engi@twitter twitter

infineon4engineers Facebook

infineon@linkedin linkedin

infineon@youtube youtube


+ Reply to Thread
Results 1 to 3 of 3
  1. #1
    New Member New Member Consultofactus is on a distinguished road
    Join Date
    Aug 2017
    Posts
    1
    Points
    15

    IRLB3813 Occasionally failing upon battery insertion

    I have successfully used the IRLB3813 in numerous portable power tool designs to drive PM brush motors in the 450W range. All these tools are powered by LiPo 18V nominal 20.5V max removable batteries and operate with the IRLB3813 as a PWM'd switch to ground (i.e. not a bridge). A new tool is presenting a problem with IRLB3813s failing upon battery insertion. These failures can be on the first insertion, or sometimes will not happen many hundreds of insertions or more. The difference in this tool design is that the motor leads are 42cm of 14AWG - considerably longer than the earlier design where the motor leads were 10cm or less. What appears to happen is that the IRLB3813 bursts into oscillation perhaps due to parasitics in the motor leads. The pcb layout is clean with a robust power and ground plane. For transient suppression a 4A schottky diode clamps the drain to the +battery and the battery bus is shunted by a 24V TVS diode. When the failure occurs a brief period of RF oscillation - somewhere around a millisecond - causes the IRLB3813 to permanently "short" at around 10 ohms. When operating properly, the gate drive is a crisp and clean 15V 2KHz
    PWM signal and the IRLB3813 handles the 500W load staying nice and cool in the process. My working hypothesis is that the IRLB3813 maximum Vds of
    30V isn't quite large enough to handle these oscillations and as a result the device breaks down. One may think that the schottky would clamp this voltage but resonance(s) in the battery may limit that clamping. I am planning to run tests with a higher voltage FET, the IRFB7437. Any feedback or suggestions would be welcome.

  2. #2

    Infineon Employee
    Infineon Employee
    Expert
    srhim1971 is on a distinguished road
    Join Date
    Sep 2016
    Posts
    14
    The oscillations can be suppressed by a snubber circuit. You can use combinations of resistors and capacitors.

    Additionally you can check whether or not the device works in the Safe Operating Range. See this Appnote:
    in chapter 2.1

    The measurement results can be compared with the simulation. Here we have an Appnote with detailled Mosfet Behaviour Analysis:

    See "documents" and " Application Notes".
    Inside
    The views expressed here are my personal opinions, have not been reviewed or authorized by Infineon and do not necessarily represent the views of Infineon.

  3. #3
    New Member New Member
    Infineon Employee
    Infineon Employee
    Blavall1 is on a distinguished road
    Join Date
    Sep 2017
    Posts
    1
    Points
    20
    Hi Consultofactus - are you still having this problem with the IRLB3813? Or is this now resolved for you? Can you let us know?
    The views expressed here are my personal opinions, have not been reviewed or authorized by Infineon and do not necessarily represent the views of Infineon.

Disclaimer

All content and materials on this site are provided “as is“. Infineon makes no warranties or representations with regard to this content and these materials of any kind, whether express or implied, including without limitation, warranties or representations of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. No license, whether express or implied, is granted by Infineon. Use of the information on this site may require a license from a third party, or a license from Infineon.


Infineon accepts no liability for the content and materials on this site being accurate, complete or up- to-date or for the contents of external links. Infineon distances itself expressly from the contents of the linked pages, over the structure of which Infineon has no control.


Content on this site may contain or be subject to specific guidelines or limitations on use. All postings and use of the content on this site are subject to the Usage Terms of the site; third parties using this content agree to abide by any limitations or guidelines and to comply with the Usage Terms of this site. Infineon reserves the right to make corrections, deletions, modifications, enhancements, improvements and other changes to the content and materials, its products, programs and services at any time or to move or discontinue any content, products, programs, or services without notice.