BQ25883: Reason for 100 ohms resistor

Eduardo Barcellos

Part Number: BQ25883

Hello,

I'm looking at the schematics for the BQ25883 development board, and at the temperature sensing pin (#7, TS) it has a 100 ohms resistor before the voltage divider, as shown below:

But I can't understand why including it. Even the BQ25883 datasheet shows the TS pin without it, as shown below:

So, my question is, why including it?

Thanks!

Eduardo

over 4 years ago

0 Ricardo over 4 years ago

TI__Genius 10385 points

Eduardo,

The schematic file you are referencing is from the reference design. In that design the battery pack is removable, so a 100 ohm resistor is added as basic ESD protection.

As you can see on the EVM schematic below, the 100ohm on the TS pin is not used.

Below is a schematic and layout checklist for your reference:

https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/196/0207.BQ2588x_5F00_SchematicChecklist_5F00_AddPCBcomment.pdf

Let me know which schematic files you want sent to you.

Best Regards,

Ricardo

0 Eduardo Barcellos over 4 years ago in reply to Ricardo

Intellectual 420 points

Thanks very much Ricardo. Once again you explained it perfectly. The PDF on the last link you posted has the circuit just like on the datasheet's "Typical Application" section, and I noticed that also no 100R resistor on TS there as well.

One last question about the schematics I included on the original post: The PG pin 9 has a 10k resistor pulling it to GND. But on the datasheet it has a 10k resistor pulling it to VREF. Since it's an open drain output, I didn't understand that 10k to GND on the schematics, specially because there's nothing using that signal. Is there a reason for that?

Thanks again,

Eduardo

0 Ricardo over 4 years ago in reply to Eduardo Barcellos

TI__Genius 10385 points

Eduardo,

Your understanding is correct. If unused, /PG can simply be left floating.

Best Regards,

Ricardo

Power management

Power management forum

BQ25883: Reason for 100 ohms resistor