• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 62 subscribers
  • Views 298 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.

TPS6521825: Do all voltage supply pins need to come up simultaneously?

adevries
Intellectual 955 points

Part Number: TPS6521825

Hello,

I'm interested in using the TPS6521825 in a circuit I am designing, and I had a question about the voltage supply pins for this IC. The voltage source I am using to power this chip is normally <5.5V, but occasionally it can spike up to 6V. According to the datasheet, this won't be an issue for almost all of the voltage supply pins (their absolute max is 7V), but pin IN_BU is only rated for an absolute max of 5.8V (see table below). Therefore, I was considering using an LDO to limit the voltage to below 5.8V, and connecting that to IN_BU. However, the rest of the voltage supply pins would be connected directly to the voltage source. This means that when power is first applied, pin IN_BU will be powered a couple milliseconds after all the other pins receive power. Will that cause any issues with the TPS6521825? Do IN_BIAS, IN_LDO1, IN_DCDC1, IN_DCDC2, etc. and IN_BU need to be powered simultaneously? Or can there be a delay in certain voltage rails coming up? 

In case what I'm describing is a little confusing, here's a block diagram of what I'm considering:

Thanks!

  • 0
    TI__Expert 3350 points

    Hi adevries,

    It depends on how your DCDC5 and 6 are sequenced. IN_BU goes to your battery backup supplies, so assuming these rails wouldn't need to be pulled up immediately, this should not be an issue. If there are voltage spikes, I recommend a decoupling cap on your input to control this so it doesn't exceed spec for IN_BU. I'm not sure if the schematic you attached is just a simplified version, but you should have input caps on all of those rails (IN_BIAS, IN_LDO1, IN_DCDC1, etc.)

    Best,
    Emily