BQ25890: TS Hot/TS Cold STAT blinking

Hey Hiroaki,

When the input is applied at VBUS and you have a TS Fault, the STAT pin should blink at a 1Hz frequency to indicate a fault. I find it odd that you only see this when the ADC 1s conversion is implemented as opposed to the one-shot mode.

Can you describe more detail about your test setup (VBUS voltage, VBAT, register settings, schematic, etc)?


Regards,
Joel H

Hi Joel,

Thank you for your quick reply. This is more like flashing with ADC than blinking with faults. VBUS is not connected when flashing. VBAT is 4.024V. Here is a register dump using i2cdump tool on linux.
# i2cdump -f -y 2 0x6a
No size specified (using byte-data access)
0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
00: 3f 06 50 1a 18 13 4f 8b 4b 44 73 02 00 13 56 56 ??P???O?KDs?.?VV
10: 00 00 00 3f 1d

I found there is no TS fault on REG0C, but the temperature is surely higher than T5 threshold. The reproduction rate is not 100%. We are still not sure what is the condition to reproduce it. We will probably stop ADC 1s conversion if it's not easy to find out the cause.

Regards,
Hiroaki Matsukawa.

Hey Hiroaki,

My other question is what rail are you pulling the STAT pin with?

One thing to note about the charger is that in order to run the ADC in battery only mode, the charger utilizes the REGN rail internally. When there is no input to the charger, the REGN rail is not active. However, when the ADC is operating, the REGN rail will turn-on momentarily for the duration of the ADC conversion.


Regards,
Joel H

Hey Hiroaki,

Let's do one thing then. Capture a waveform of the following:
STAT pin oscillation
TS pin voltage (as measured as close as possible to the pin of the charger)
REGN voltage (as measured as close as possible to the pin of the charger)

You also mentioned this behavior is not consistent. We expect that no TS fault will be present in battery only mode unless you are operating in OTG (reverse boost) mode. The TS fault is only meant for either charging mode or OTG mode.


Regards,
Joel H

Hi Joel,

This is a waveform when the LED is flashing. Hope this would help.

On the contrary, this is a waveform when the LED is not flashing.

Regards,

Hiroaki Matsukawa.

Hi Hiroaki,

We were able to replicate this behavior as well. We recommend to use/set "One-Shot" for ADC measurement.

Regards,
Alejandro I.

Hi Alejandro,

We find it still flashes at the moment of issuing one-shot ADC(CONV_START=1). Is there another workaround?

Regards,
Hiroaki Matsukawa.

Hi Hiroaki,

I think there might be some misunderstanding. So, to clarify:
At the beginning of this thread you mentioned that the IC is not blinking in One-Shot Mode (CONV_RATE = 0). But, it is blinking in 1s Continuous Conversion (CONV_RATE = 1). Yes?
May you please reinstate the error/behavior that you are experiencing?

The STAT pin should be blinking at 1Hz when input overvoltage, TS fault, timer fault, input or system overvoltage.

-Thanks

Hi Alejandro,

Sorry for the misunderstanding statement.

The STAT LED flashes when the temperature is under T1 or above T5 with no VBUS and with ADC. The LED flashes at a rate of 1 time per second with 1s continuous ADC(CONV_RATE=1). It does not flash "at a rate of 1 time per second" with no 1s continuous ADC(CONV_RATE=0), but it still flashes at the same time as issuing CONV_START=1.

Regards,
Hiroaki Matsukawa.

Hi Alejandro,

Thank you for suggesting the alternative solution. This is not ideal, but we are happy we found the solution anyway.

Regards,
Hiroaki Matsukawa