BQ25895: I2C communication problem

MJ Jeon

Genius 5240 points

Part Number: BQ25895
Other Parts Discussed in Thread: EV2400

Please inquire about the cause of intermittent I2C read failure when the init reg value is set as follows.

Please check if there is a problem with the register value.

1. In some cases, I2C communication intermittently delays. Please check. (Refer to the waveform below)

2. The waveform below seems to be a symptom of clock stretching. Is it correct? What is the cause?

At this time, charging is operating normally. Is it normal operation?

What state should it be in order to be released?

This symptom is common in all samples.
Sample conditions are as follows.

VBUS: 12V
IVBUS: 0.67mA
VBAT: 3.7V
IBAT: 2A
VSYS: 3.7V
ISYS: 11mA

The peripheral circuit diagram of BQ25895 is as follows.

over 4 years ago

0 Ning T over 4 years ago

TI__Guru 57781 points

Hi,

Please visit https://e2e.ti.com/support/power-management/f/196/t/874557 for BQ2589X: Schematic Review and PCB Layout Design Tips and https://e2e.ti.com/support/power-management/f/196/t/875386 for BQ2589x/BQ25898x FAQs.

What I2C adaptor are your using?

Thanks,

Ning.

0 MJ Jeon over 4 years ago in reply to Ning T

Genius 5240 points

Hi, Ning

Is the'I2C adapter' asking for an I2C connected MCU? Or are you asking for a 12V power supply?

Thanks,

MJ Jeon

0 Ning T over 4 years ago in reply to MJ Jeon

TI__Guru 57781 points

MJ,

An example is EV2400 at https://www.ti.com/tool/EV2400

Thanks,

Ning.

0 MJ Jeon over 4 years ago in reply to Ning T

Genius 5240 points

Hi, Ning

Like the data you sent, I2C communication is not performed by connecting EVM or EVK to the outside. 12V Input is provided to the product as a Power Adapter and charging is in progress.

Also, the contents of the FAQs and the contents I have asked do not seem to be related.

The waveform of the first inquiry is the measurement of I2C (SDA, SCL) in the schematic. It is measured in the actual product.

For reference, we will deliver the specifications of the externally approved Power Adapter.

Thanks

0 Ning T over 4 years ago in reply to MJ Jeon

TI__Guru 57781 points

MJ,

Will get back to you during business hours in the next week.

Thanks,

Ning.

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

TI__Guru 57781 points

MJ,

The device uses I2C compatible interface. Please check if the data communication meets the I2C bus specifications.

Thanks,

Ning.

0 MJ Jeon over 4 years ago in reply to Ning T

Genius 5240 points

Hi, Ning

In the contents of the first inquiry, I attached a circuit diagram used as an I2C interface. Vbus input voltage is used as 12V and BQ25895 is controlled through I2C interface in MCU. Is there a problem with the configured circuit?

To summarize the inquiry details, I am trying to start communication by setting an initial register value to control BQ25895, but communication is intermittently disconnected. We asked you to confirm why communication is intermittently disconnected and charging is in progress even when communication is disconnected.
Also, please check whether the communication disconnection is related to the'clock stretching' shown in the datasheet.
Can you tell us in detail what part to check for the confirmation of the'I2C bus specification' you posted? When viewed from the circuit diagram, it is normally connected and communication is being performed through the I2C interface.

Thanks,

0 Ning T over 4 years ago in reply to MJ Jeon

TI__Guru 57781 points

MJ,

The charger device never does clock stretching. SCL is input only for the charger and the charger can’t pull SCL low. Please check if the host or other slaves in the system are pulling SCL low.

Thanks,

Ning

0 MJ Jeon over 4 years ago in reply to Ning T

Genius 5240 points

Hi,

Among the contents on page 29 of the datasheet, there is a content on 'clock stretching'.
Are you saying it's not about this charger IC?
If so, why is the content stated?
In addition, can you check whether the 'init register' in the first inquiry is correct?

Thanks,

0 MJ Jeon over 4 years ago in reply to MJ Jeon

Genius 5240 points

0 Ning T over 4 years ago in reply to MJ Jeon

TI__Guru 57781 points

Hi,

The d/s only introduces the clock stretching information. But SCL is input only for the charger and the charger can’t pull SCL low. Please check if the host or other slaves in the system are pulling SCL low.

Thanks,

Ning.

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BQ25895: I2C communication problem