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BQ25505: VB_SEC_ON

Part Number: BQ25505



 Let me ask a the short question.

・Could you tell me about the ON condition and voltage of VB_SEC_ON?

 (Will it be on only while VBAT_OK is high? And what will happen to the output voltage?)

best regards


  • Hello TATSU,

    Section 7.3.5 details, "When VBAT_OK goes low, indicating that the secondary rechargeable battery at VBAT_SEC is below the VBAT_OK threshold, the VB_SEC_ON output goes high followed by the VB_PRI_ON signal going low in order to connect VBAT_PRI to the system." In addition, it says, "The drivers are powered by an ideal diode OR of the secondary battery at VBAT_SEC and the primary battery at VBAT_PRI, even during cold-start, giving each enough drive for up to 2 nF of gate capacitance of external back-to-back PMOS FETs."

    So delving into this, VB_SEC_ON will go high when VBAT_OK goes low. The rail is provided by diode or of VBAT_SEC and VBAT_PRI.


    Mike Emanuel