VBST_IN voltage in FS26

[Changwoo82]

Hi~

In the specification, FS26 is operated with a voltage of 2.7V at VBST_IN.

However, VBST_IN is simply the net before the boost inductor and not a pin in FS26.

How does FS26 monitor the battery voltage of 2.7V?

[ErikaC]

Hello,

2.7 V is the minimum input operating voltage before the FS26 powers down.
VBOS_UVL typ. value is 3.2V, which means that in low battery voltage conditions where VBOS is supplied by VSUP pin, if we consider a 0.5V voltage drop in VBST diode, we get 2.7 V at VBST_IN.
In normal mode operation, VBOS is always monitored, that is why we have a difference with Figure 9 where the condition is VBOS_POR and not VBOS_UVL.

As there were some confusions about this, we will update the figure 8 from the datasheet with the one below:

Regards,

[ErikaC]

I am working on your question, as soon as I have an answer I will let you know. Thank you for your patience.