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BQ27530-G1: Internal Temperature Sensor BAT_DET

Chris Pettus
Prodigy 100 points
Part Number: BQ27530-G1
Other Parts Discussed in Thread: BQ24161,

I am using the BQ27530-G1 together with the BQ24161 battery charger.  The battery pack that is used in the device is comprised of two 18650 Li-Ion cells in parallel with a capacity of 4800 mAh and does not have a temperature sensor.  I have configured the BQ27530 to use the internal temperature sensor by clearing the TEMPS bit in OpConfig register.  I read in another post on this forum that to use the internal temperature sensor and detect the battery that the BI/OUT should be pulled to VCC, pin D1 on chip, with a 1.8M resistor and a 33nF capacitor to ground.  Also BI/TOUT should be connected to TS with a 18.2K resistor and TS connected to ground with a 10K resistor.  In this configuration the BAT_DET flag is always set, with or without the battery connected, and the fuel gauge is enabling charge CE on the BQ24161.

Is there something else that need to be configured in the BQ27530 to correctly detect when the battery is removed?

Register settings:

OpConfig = 0x6166

OpConfigB = 0x6F

OpConfigC = 0x3C

Charger Options = 0x20

Charger Reg 00 = 0x00

Charger Reg 01 = 0x00

Charger Reg 02 = 0x5C

Charger Reg 03 = 0x02

Charger Reg 04 = 0x00

Charger Reg 05 = 0x02

Charger Reg 06 = 0x00

Charger Reg 07 = 0xC8

Status:

Control Status = 0x6285

Flags = 0x0138

Application Status = 0x00

ChargerStatus = 0x00

Charger Reg0 = 0x30

Charger Reg1 = 0x30

Charger Reg2 = 0x58

Charger Reg3 = 0x8E

Charger Reg4 = 0x45

Charger Reg5 = 0xD2

Charger Reg6 = 0x00

Charger Reg7 = 0xC0

  • 0
    TI__Mastermind 41431 points

    Hi, Chris,

      I'm sorry for answering your question so late.

      When an external thermistor is used, a 18.2-kΩ pull-up resistor between the BI/TOUT and TS pins is required, so, if you use the internal thermistor, please don't use the 18.2-kΩ pull-up resistor.

      To detect battery removal correctly,  it's necessary to pull up the BI/TOUT pin (It's actually BI only function now) to VCC by a 1.8M resistor, and then your battery pack needs to have a pin with about 10K resistor (it's the NTC thermistor resistance when use an external thermistor) to PACK-;  when the battery pack is connected, the BI pin will be logic low, otherwise, it's logic high.

      Please let me know if you have any other questions. 

    Thanks!

    Phil