• State Resolved
  • Replies 2 replies
  • Subscribers 47 subscribers
  • Views 46 views
  • Users 0 members are here
Support feedback
Options
Options
Related

Original question:

LM248: LM248 Junction-to-case resistance

LM248: Negative Rail Going slightly positive on startup

Timothy Coulter
Prodigy 100 points

Part Number: LM248

N15V Startup.pdf 

My -15V rail powering the LM248 goes slightly positive on startup, to around 50mV. Is there concern that this might cause damage to the part on startup?

There is nothing in the LM248 datasheet about this situation. When the -15V is going slightly positive, the +15V is at 0V.

  • +1
    TI__Mastermind 29288 points

    Timothy,

    I don't think the -50mV is a real concern.  The op amp is a bipolar device and to damage the device you would have to forward bias junctions that should be reversed bias.  This would take at least 300mV (closer to 600mV or 700mV).  Also, the unwanted voltage negative would need to provide enough current to do damage.  I doubt that the 50mV would do any damage.  I think small reverse voltages like this are common when supplies cycle off.  If you told me you had -1V or -2V I would be concerned, but not -50mV.

    Best regards,  Art

  • 0 in reply to Art Kay
    Prodigy 100 points

    Thank you for your response.