BQ25883: Read the register before ADC ready

Kazuto Tatsumi

Part Number: BQ25883

Hi experts,

My customer found TS value was being changed significantly (0x22 = DB->46->FC) within very short term even in the stable temperature room.

When this issue occurs, the MCU reads 0x22 every 1 seconds. However, there is no issue when the MCU wait for ADC conversion ready and then read 0x22.

Is it necessary to wait for ADC ready for every cycle? I think ADC always keeps the previous value so the value cannot be changed drastically, according to the datasheet, is that correct?

Regards,
Kazuto

over 4 years ago

+1 Angelo Zhang87 over 4 years ago

TI__Genius 11850 points

Hi Kazuto,

Based on the information you provided, I'm assuming the ADC is set to one-shot conversion mode. Is this correct?

For one-shot mode, please wait until the ADC conversion is done before reading the result. For continuous conversion mode, you can read the ADC result at any time.

Best regards,

Angelo

0 Kazuto Tatsumi over 4 years ago in reply to Angelo Zhang87

TI__Intellectual 2820 points

Hi Angelo,

Understood. Is there any disadvantage to use continuous conversion mode? affect power consumption compare to one-shot every second?

Regards,
Kazuto

+1 Angelo Zhang87 over 4 years ago in reply to Kazuto Tatsumi

TI__Genius 11850 points

Hi Kazuto,

Yes, you are correct. The quiescent current is higher (by a few hundred uA) when the ADC is enabled in continuous mode because the ADC circuitry is always active. Otherwise, it is fine to run the ADC in continuous conversion mode.

Best regards,

Angelo

0 Kazuto Tatsumi over 4 years ago in reply to Angelo Zhang87

TI__Intellectual 2820 points

Hi Angelo, thanks! I understood the solution.

0 Kazuto Tatsumi over 4 years ago in reply to Angelo Zhang87

TI__Intellectual 2820 points

Hi Angelo,

My customer sets 0x15 = 70. In this case ADC is disabled. Is ADC necessary to be enabled no matter which ADC mode continuous or one-shot?

Regards,
Kazuto

+1 Angelo Zhang87 over 4 years ago in reply to Kazuto Tatsumi

TI__Genius 11850 points

Hi Kazuto,

No, you do not have to enable the ADC if you are not using it. It is fine to disable the ADC if it is not needed in the customer's application.

Best regards,

Angelo

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BQ25883: Read the register before ADC ready