bq24195 Fault Reg always equals to 0x23

S L61

Other Parts Discussed in Thread: BQ24195

Dear all,

I always get a fault from the fault register (REG09 = 0x23) no matter when charging or discharging.

BQ24195 can charge or discharge without problems. When I increase the temperature of the themistor, the charger can stop charging. All things look fine except the 0x23 fault.

The figure below is my design. Is there anything wrong with it? Thanks.

S L61

over 9 years ago

0 S L61 over 9 years ago

Intellectual 780 points

Is there anybody encountered similar problems before? The schematic is designed according to the data sheet.

0 Steven Bangdiwala over 9 years ago in reply to S L61

TI__Expert 8690 points

Hi,

In page 18 of datasheet you will find information about the thermistor and the formulas to calculate what resistor values you need in order to fix the thermistor fault. The fault you are getting is due to having the incorrect values for the resistors, which are dependent on what thermistor you are using.

Thanks,
Steven

0 S L61 over 9 years ago in reply to Steven Bangdiwala

Intellectual 780 points

Hi StevenB,

Thanks for your reply. The resistance values in our design are referred to both page 18 of datasheet and EVM board and the thermistor we use is NTCLE213E3103FLB0. According to EVM, RT1 = 5.23kOhm, RT2 = 30.1kOhm. However, I still got the fault. Is there any mistake? Thanks.

S L61

0 Steven Bangdiwala over 9 years ago in reply to S L61

TI__Expert 8690 points

Try removing R31, the 10k resistor in parallel is used if there is no thermistor connected.

Thanks,
Steven

0 S L61 over 9 years ago in reply to Steven Bangdiwala

Intellectual 780 points

Hi,

I don't understand why removing R31. Since R31 is a NTC thermistor, how can I sense the battery temperature change without it?

Thanks,

S L61

0 Steven Bangdiwala over 9 years ago in reply to S L61

TI__Expert 8690 points

You are right, the R31 is the thermistor, I thought it was a 10k resistor. From what I see, the resistor values are close to the correct values, which should be R29 = 28k and R30 = 5.49k (based on the calculation tool www.ti.com/.../slvrbe3 and using the beta value from the NTCLE213E3103FLB0 datasheet), so it could be something that is not connected correctly. The fault comes from TS2, make sure both TS1 and TS2 are connected to the same node.

What is the voltage on TS1 and TS2 pin when you have the fault? Can I see a complete schematic?

Thanks,
Steven

0 S L61 over 9 years ago in reply to Steven Bangdiwala

Intellectual 780 points

The voltages on TS1 and TS2 are both 2.9V in boost mode and 2.8V when charging.
TS1 and TS2 are connected to the same node. I use a 0 ohm resistor to short them.
Could you give me your email so that I can send the complete schematic to you?

Thanks,
S L61

0 Steven Bangdiwala over 9 years ago in reply to S L61

TI__Expert 8690 points

I have sent you a message.

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bq24195 Fault Reg always equals to 0x23