11 Replies Latest reply on Sep 23, 2015 9:45 PM by MichaelF_56

    BCM20736S HIDOFF problem

    legic_1490776

      My application invokes HIDoff to go into a deep sleep, and works fine on the BCM20732S.

       

      When I try to enter HIDoff mode, at first it seems to work - the current draw drops to near 0.

      But then, about 6 seconds later, the current rises to 2mA and stays there.  The chip does not wake up at this point - it still appears to be sleeping, and will wake up later from an interrupt just fine.  But it is drawing a lot of power.

       

      I am analyzing this using a power meter that logs the current draw over time.

      I've attached screen shots with annotations.

      In the first image you can see the device running, then there is a burst of current when it enters HIDoff, and then it is off.

      Then, after about 6 seconds, something happens that leaves it running at a fairly high level.

       

      The second image shows a continuation where I then press a button to wake up the device and it indeed wakes up and resumes normal operation.

       

      The identical board design and firmware works fine with the 20732S.

       

      Any ideas?