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Misleading statement about TS function of BQ25120A

cyber_v1
Associate III

Hi,

Our development board uses BQ25120A for battery management.

In the datasheet section 10.2.2.1 Default Settings, there is a statement:

• If the function is not needed, connect TS to the center tab of the resistor divider between VIN and the ground.
(pull up resistor = 14 kΩ, pull down resistor = 14.3 kΩ)

We didn't need the TS function at this time, so we followed that advice. However, upon assembly, the charging did not work. We figured out it was because of a TS fault. Checking the datasheet again, section 9.3.16 External NTC Monitoring (TS) says: "To disable the TS function, pull TS above TSOFF threshold." Then checking the TSOFF threshold, it's minimum value is 55% of VIN, and the 14k/14.3k divider only gives around 50%. I believe these values are applicable for the case when TS function is used with a 10k NTC (b=3370), contrary to what 10.2.2.1 says. And if the function is not needed, the pull up resistor should be 10k or less. So it is either misleading, or there is a mistake in the stated pull up resistor value.

Regards

1 ACCEPTED SOLUTION

Accepted Solutions
Peter BENSCH
ST Employee

Users of this forum for devices from STMicroelectronics should feel very honored that you are asking a question about devices from Texas Instruments – I'm just afraid that you won't get many answers.

Regards
/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

View solution in original post

6 REPLIES 6
Peter BENSCH
ST Employee

Users of this forum for devices from STMicroelectronics should feel very honored that you are asking a question about devices from Texas Instruments – I'm just afraid that you won't get many answers.

Regards
/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

LOL

Sorry

Andrew Neil
Super User

You realise that the BQ25120A is a TI (Texas Instruments) device, right?

https://www.ti.com/product/BQ25120A

For support/feedback with TI devices, you need to go to TI - it is nothing to do with ST!

https://www.ti.com/product/BQ25120A#support-training

https://www.ti.com/info/customer-support.html 

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

Thanks. I guess being fever-ish doesn't help with thinking straight.

If you do raise this on the TI forums, please post a link here - so that anyone else who arrives here via search will be able to follow it!

 

Get well soon!

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.