• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 464 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

LM3880: External Enable Signal from Power-Good of TPS7A26 3.3V LDO

Soumyadeep Biswas
Prodigy 50 points
Part Number: LM3880
Other Parts Discussed in Thread: TPS7A26,

Is it recommended to use TPS7A26 +3.3V output as VCC for LM3880 and the Power-Good output of the same TPS7A26 as the "External Enable signal" as illustrated in Figure 8-5 on Page 16 of LM3880 datasheet?

  • 0
    TI__Genius 14827 points

    Hi Soumyadeep,

    Yes, using the TPS7A26 for this purpose would be okay. 

    Best,
    Ryan

  • 0
    Prodigy 50 points

    In my application with a single +12V DC input supply, I am not able to design the power-down sequencing with LM3880. When the +12V supply is turned off the VCC to LM3880 will also be off, so the power down sequencing which is controlled by the enable signal will not work. Please suggest. 

  • 0 in reply to Soumyadeep Biswas
    TI__Genius 14827 points

    Hi Soumyadeep, 

    I don't quite understand. Are you asking for a solution where the VIN is off, but still has a VCC to power the LM3880?
    Best,
    Ryan

  • 0 in reply to Ryan Chen
    Prodigy 50 points

    Hi Ryan

    Thanks for your reply. Yes, if the single VIN (+12V) is suddenly turned off, is there any way I can do the power-down sequencing with LM3880 without any other separate VIN to power the LM3880? Actually I was planning to use the TPS7A26 to generate the +3.3V and PG signal from +12V VIN. This is ok for the power-up sequence as you confirmed in your earlier reply. But then I realized that power-down sequencing may not work with this scheme because the +3.3V VCC of LM3880 will also instantly turn off along with +12V. My application is to sequence the drain and gate voltages of RF power amplifiers during power on and power off. Any suggestions will be great.

    Thanks

  • 0 in reply to Soumyadeep Biswas
    TI__Genius 14827 points

    Hi Soumyadeep, 

    I do not think you can. When you power down the VIN there will be no other source that can power the 3.3 V for VCC and PG for enable. 

    Best,

    Ryan