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BQ25731: About Vsys_min

Part Number: BQ25731
Other Parts Discussed in Thread: BQ25730


I understand that BQ25731 is an IC without power path function.
However, BQ25731 datasheet contains Vsys_min information.
For example, the table below.

Let me ask you two questions in this background.

1.Is the setting value of Vsys_min a fixed value?
       Or is it possible to set by register like BQ25730?

2.Could you tell me the reason why Vsys_min is mentioned even though it does not support the power path function?

Best regards,

  • Hi Yusuke,

    1. For the BQ25731, VSYS_MIN is a fixed value based on the CELL pin configuration. The VSYS_MIN thresholds for each CELL pin setting are shown in Table 9-2. VSYS_MIN cannot be programmed through the registers. This is different from the BQ25730.
    2. VSYS_MIN is the battery low voltage threshold (Section provides more details). When VBAT < VSYS_MIN, the charge current is clamped below 384 mA. The datasheet refers to this threshold as "VSYS_MIN" on the BQ25731 to stay consistent with the other chargers in the family, but it may be easier to think of this as BATLOWV instead, since VSYS is not regulated above VSYS_MIN. This is because the BQ25731 is a non-power path charger, unlike the BQ25730.

    Best regards,