• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 249 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS7A4501-SP: TPS7A4501-SP

Edwin Molina
Prodigy 40 points
Part Number: TPS7A4501-SP

Hello, 

The datasheet for the TPS7A4501-SP states that the device has protection against reverse voltage applied at the output:

"The devices are protected against both reverse input and reverse output voltages. In battery-backup applications where the output can be held up by a backup battery when the input is pulled to ground, the TPS7A4501-SP functions as if it has a diode in series with its output and prevents reverse current flow."

Are there any limitations on how long reverse voltage can be applied?

Thank you

  • 0
    TI__Genius 10970 points

    Hi Edwin,

    Since this is not specified in the datasheet, I will need to look into it to see if there is any rough guidance we may be able to provide. Is there a specific period of time you expect this condition in your design? 

    As long as the rated Operating Conditions of the device are respected, it may not be a major concern but I will want to confirm this is accurate. Of course, it is always preferable for error states to be as brief as possible. 

    Thanks,

    Sarah

  • 0 in reply to Sarah Koch
    Prodigy 40 points

    Hi Sarah,

    Thank you. I am using this part in a satellite application where the output will be cross-strapped with a redundant TPS7A4501-SP. Only one of the LDOs will be powered at any given time. The duration could be several years. The application note implies that the TPS7A4501-SP is suitable for back up battery applications where the LDO output can be back driven. Was curious if there are any limitations on this use case. The unpowered LDO would see 11V at it's output. 

    The datasheet states "the TPS7A4501-SP functions as if it has a diode in series with its output and prevents reverse current flow", so I expect this use case to be ok, but do not know much about the internal blocking diode. 

    Thank you,

    Edwin

  • 0 in reply to Edwin Molina
    TI__Genius 10970 points

    Thanks for the additional details Edwin!

    Just to make sure I have a clear understanding of the configuration - only the outputs of these devices are tied, correct? The inputs are coming from separate rails so that the input of the secondary device is 0V while unpowered? It sounds like this is the case, but I don't want to assume. 

    With your output voltage, I expect this condition would be fine as it is within the rated operating conditions of the device and redundancy is a commonly supported configuration among space-rated devices. I'm running a high-level sanity check by our Design team and should have an update for you here in a day or 2.

    All the best,

    Sarah

  • 0 in reply to Sarah Koch
    Prodigy 40 points

    Hi Sarah,

    Just to make sure I have a clear understanding of the configuration - only the outputs of these devices are tied, correct? The inputs are coming from separate rails so that the input of the secondary device is 0V while unpowered? It sounds like this is the case, but I don't want to assume. Yes, this is correct. Each LDO will have its own independent supply, one of which will be 0V. 

    Thank you. Would you also be able to inquire about the reverse voltage rating for the reverse protection diode? This may not be easy to determine, but I thought I would ask. Would like to apply less than 50% of its rating to help mitigate single event effects when reverse biased. That is, if the reverse protection circuit includes a diode.

    Thank you,

    Edwin

  • 0 in reply to Edwin Molina
    TI__Genius 10970 points

    Hey Edwin,

    The feedback from our Design team was that in principle this should work. There are no red flags that stand out about what you are describing.

    Because this configuration is not technically included in the full characterization and testing that we otherwise use to qualify the part in terms of MIL-PRF spec, I can't make any conclusive claims about overall impacts to longevity/aging. The data just doesn't exit. However, as before our Design team generally feels that operating at 11V does give a lot of margin in this regard. 

    I am less certain regarding the SEE-focused derating you hope to apply. If there are any insights the designers may have, I'll share them here.

    Thanks,

    Sarah

  • +1 in reply to Sarah Koch
    Prodigy 40 points

    Thank you Sarah for the quick response. 

    I think this addresses my concern. If you have additional information, I would appreciate it!

    Thanks,

    Edwin