BQ25890: Question for thermistor circuit

Xiaoqiang Shen

Intellectual 420 points

Part Number: BQ25890

1) What does the percentage mean for temperature here?

2) The RTHhot and RTHcold means which value?

over 4 years ago

+1 Ning T over 4 years ago

TI__Guru 57481 points

Hi,

1) (VTS/VREGN)% may back calculate the thermistor resistance (RTH). RTH can be used to calculate the battery temperature. The battery vendor should be able to provide the equation.

2) In the example, RTHhot = RTH t5, i.e. thermistor resistance at T5=60C (hot). RTHcold = RTH t1, i.e. thermistor resistance at T1=0C (cold).

For RT1 and RT2 calculation tool, please refer to http://www.ti.com/lit/zip/slurax7.

Thanks,

Ning.

0 Xiaoqiang Shen over 4 years ago in reply to Ning T

Intellectual 420 points

There are 2 modes in datasheet. Generally I think it's BUCK mode, but when use boost mode?

0 Wyatt Keller over 4 years ago in reply to Xiaoqiang Shen

TI__Guru** 105620 points

Hello,

The charger can operate the buck converter in reverse, turning the buck into a boost with the output on VBUS for OTG applications that require 5V and up to 2.4A.

The charger will use different temperature thresholds in boost mode operation.

Sincerely,

Wyatt Keller

Power management

Power management forum

BQ25890: Question for thermistor circuit