Why STNS01 PUR does not switch to the battery when the chip is only connected to a battery?

[MAhma.7]

Hello,

I am using a STNS01 in my circuit for the power management. The problem is when I only have a charged battery (4.1 v) connected to the BAT pin, it does not switch to the battery voltage. As if the chip is in shutdown mode (I do not know why, the SD pin is internally pulled down and I do not activate it). To release the shutdown mode, I need to connect the IN pin to the USB and when I unplug the USB again, this time it switches to the battery (I think releasing from shutdown).

Can anybody let me know why it does not switch to the battery initially? Even I pulled down the IN pin to be sure its voltage is zero compered to the BAT pin voltage (4.1 volt).However, it did not help.

I also checked the operating condition table in the datasheet. It is kind of weird for me. Because if the voltage of the battery is in the valid range (3 ~ 4.2 v) it never switches to the battery. I think the table should be modified as below.

 

Best,

Mehrdad

[miket6000]

I know this is an old post, but it still comes up in searches. I doubt the original user will reply, but this is the behaviour I noticed when I was accidentally driving CEN low from the micro controller. There is a note in the datasheet that CEN must be held high or floating for correct operation, I suspect this is what they mean.