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Original question:

BQ25570： About one way to avoid cold start?

BQ25570: How to fasten the cold start

Nicky Andre Prabatama
Prodigy 40 points
Part Number: BQ25570

Tool/software:

In this case, i have a project which use a BQ25570 IC with an RF energy harvester. My RF harvester can provide 0.3 Volt - 0.4 Volt Ouput which is under the requirement of the minimum cold start which should be 0.6 Volt. So in this case how i can fasten my cold start process? i saw some thread with using some PFET and NFET could someone explain me about this?. I also saw one article mentioning that some kind of charging capacitor first then fed it into the BQ25570. How we can do this?

  • 0
    TI__Mastermind 34255 points

    Hello,

    The minimum input voltage to start the cold start circuit is 600 mV. "The cold start circuit needs at least VIN(CS), 600 mV typical, to charge VSTOR up to 1.8 V." Basically you need this minimum voltage.

    On Page 19 of the d/s it says, "It is highly recommended to add an external PFET between the system load and VSTOR. An inverted VBAT_OK signal provided by VB_SEC_ON can be used to drive the gate of this system-isolating, external PFET. See the Energy Harvester Selection applications section for guidance on minimum input power requirements." This is to shorten cold start by limiting the system load. However, the 600 mV minimum input is still needed.

    Regards,

    Mike Emanuel