TPS54678: TPS54678_UVLO Calculation

Srikanth Kacchu1

Part Number: TPS54678
Other Parts Discussed in Thread: TPS62867

Hi Team

We are using TPS54678 in our design. I am confused with the datasheet calculation on VSTART and VSTOP at Equation 2 & 3.

If I want to enable the IC only when the minimum input voltage is 4.5V, what are the resistors I want to use?

Please provide some additional information on VSTART and VSTOP.

Regards

Srikanth Kacchu

over 4 years ago

0 Chris Glaser over 4 years ago

TI__Guru**** 150900 points

Hi Srikanth,

First, the TPS54678 is an older device. I would recommend using the TPS62867. If you need the precise UVLO, you can use an external SVS.

As the D/S explains, if you want the turn on voltage to be 4.5V, then set Vstart to 4.5V. There is hysteresis on this voltage, so you will get a lower Vstop voltage.

So, for R1 = 10k and Vstart = 4.5V, then Vstop = 4.06V. From the second equation, R2 then = 4.05k.

Thanks,

Chris

0 Srikanth Kacchu1 over 4 years ago in reply to Chris Glaser

Expert 1255 points

Hi Chris

Thanks for the solution.

We have finalized this part in our design. Do we have any impact like EOL, supplies,etc?

Regards

Srikanth Kacchu

0 Chris Glaser over 4 years ago in reply to Srikanth Kacchu1

TI__Guru**** 150900 points

Thanks for explaining.

Here is our EOL policy: https://www.ti.com/support-quality/quality-policies-procedures/product-life-cycle.html

Here is the current inventory of this device: https://www.ti.com/product/TPS54678#order-quality

Especially in this demand environment, it is strongly recommended to place orders soon to secure the devices you need for your builds.

Chris

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TPS54678: TPS54678_UVLO Calculation