STBC15 output current?

[icharala]

Hi all,

I recently stumbled upon STBC15 and I am interested in integrating it into our next design. However, I am lacking a critical parameter from the datasheet: what is the typical and maximum allowed current flowing from VBAT to the OUT pin?

[Peter BENSCH]

Welcome @icharala, to the community!

depending on the configuration of the pins ISET0 and ISET1 this charge current is either 10mA, 20mA, 30mA or 40mA (see data sheet, table 8).

Hope this answers your question?

Regards
/Peter

[icharala]

Hello @Peter BENSCH and thank you for your quick response! This is the charge current (from charge input towards the battery) and this is clear.

But from what I see the component has a power path from the battery towards OUT (when the transistor M3 in on and there is no voltage on CHGIN). I am asking for the recommended/maximum current on that path.

I guess a safe assumption would be "no more than the charge current" but I am curious if there is any chance to be bigger than 40mA...

[Peter BENSCH · Accepted solution]

Sorry, I hadn't read your question correctly. The maximum current for the M3 transistor is indeed not specified, but it results from the intended applications.

The LiIO batteries typically used in low current applications are not only charged with max 1C, but normally also discharged with max 1C.

In the data sheet, table 5, you will find the Rdson of the transistors M1...M3 = 3 ohms,  i.e. all identical parameters. Because this Rdson generally determines the maximum current in the FET, this results in the same maximum current of 40mA as the max charging current.

When selecting the current through M3, please bear in mind that its power dissipation increases quadratically with the current.

Regards
/Peter

[icharala]

Gotcha, that makes sense.

And yes, I can estimate the power dissipation from the resistance. Would be nice to know the absolute maximum though 🙂