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Original question:

TLV5604: TLV5604 output query

TLV5604: Power on sequencing

Needhu Gunasegaran
Intellectual 2890 points
Part Number: TLV5604

Hey Team,

My customer is using the TLV5604 in one of our Designs and are observing short output voltage “glitches” during ramp-up of supply voltages.

As mentioned here below, the Avdd rises and Vout follows. Once Dvdd rises Vout drops.

https://e2e.ti.com/support/data-converters-group/data-converters/f/data-converters-forum/623544/tlv5604-tlv5604-output-query

However, I couldnt find any chapter on power on sequencing on the DS. I only saw a block mentioning internal power on reset.

Do you have an App note explaining this or more information on a DS?

Thanks and Many Regards,

Needhu

  • 0
    TI__Mastermind 42243 points

    Hi Needhu,

    I wasn't able to find any app notes, but the video mentioned in the forum post you shared is helpful (link here).To summarize, the device needs to have the correct power sequence so it can power up to known states. In addition, multi-supply devices usually share ESD diodes between them, which can cause the supply pins to see invalid voltages. 

    Looking at the absolute max ratings of the TLV5604, you can see that the max value for the reference is AVDD +0.3V and the max supply voltage difference between AVDD and DVDD is +/-2.8V. This lets you know that the reference always needs to be below AVDD so the reference cannot be powered on before AVDD, and that AVDD and DVDD must be ramped so they stay within 2.8V of each other. DVDD is usually powered on first so that the digital power-on reset circuitry can power up the device to its known state. If AVDD is powered on first, the output voltage may turn on with some digital controls in an unknown state that is corrected when DVDD is applied (hence the glitch), or it may apply an invalid voltage to DVDD and cause the power-on reset circuitry to incorrectly startup the device.

    This external article was written by TI Engineers (link here) and it gives a similar explanation to the TI training video. 

    Best,
    Katlynne Jones