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Stbc03. What will happen if IN voltage less than the battery voltage?


Hello, please help me understand:

1) What will happen if IN voltage less than the battery voltage? What voltage will in SYS in this case?

2) Сan I connect SYS pin to IN? I'ts safe?

Winfred LU
ST Employee

1) shall not happen

Battery floating voltage is adjustable up to 4.45 V.

The minimum Vin will be 4.75 V when Vfloat is set to 4.45 V.

2) take your own risks

It means to skip the protections within STBC03.

Thanks for the answer. Can you please clarify one more question:

What if the battery is fully charged (4.2 V) and we supply 4.2 V or less( for example, 3.9 V) to the IN pin. In this case, what will be the voltage on the SYS pin?

It will not work.

There is no grantee outside the range of operating input voltage : 4.45 V to 5.4 V

Associate II


We could use STBC3 for stand alone application. I want to charge a mini battery as below specification. battery.jpeg 


I am planing to draw a pcb that contains USB socket and its power will  be come from 5V phone charger. May I use the STBC3  stand alone to charge this battery or should i put mcu to control charger limits. I confused. Previously I use TP4056 IC to chage higher capacity. It is the first time i am going to charge such a lower batter.  May you give some advise to me.

Best regards.