BQ25601D: /QON Circuit

Sadanori Kato

Guru 36530 points

Part Number: BQ25601D

Hi,

Could you please tell me the voltage of "Vpull-up" and the value of the pull-up resistor regarding the /QON circuit?

Best regards,
Kato

over 5 years ago

0 Joel Hernandez II over 5 years ago

TI__Mastermind 25800 points

Hey Sadanori,

The voltage is a derivative of the battery voltage or the input voltage. It is the higher of VBUS - 1.4V or VBAT - 0.7V. And the pullup resistance is ~200kOhm.

Regards,

Joel H

0 Sadanori Kato over 5 years ago in reply to Joel Hernandez II

Guru 36530 points

Hi Joel-san,

Thank you for your prompt reply.

I would like to confirm just in case but it seems that the absolute maximum rating of the /QON terminal may be exceeded when 13.5V is applied to the VBUS terminal and "VBUS - 1.4V" is selected as the Vpull-up voltage.
Additionally, how does the BQ25601D switch between "VBUS - 1.4V " and "VBAT - 0.7V" during operating ?

Best regards,
Kato

0 Joel Hernandez II over 5 years ago in reply to Sadanori Kato

TI__Mastermind 25800 points

Hey Kato,

This is an internal pullup. The pin cannot handle external voltages above 7V.

And the switch between VBUS or VBAT is proprietary information. We cannot provide this.

Regards,

Joel H

0 Sadanori Kato over 5 years ago in reply to Joel Hernandez II

Guru 36530 points

Hi Joel-san,

Thank you for the information.

I understand that the architecture to switch between VBUS and VBAT cannot be disclosed.
Is my understanding correct that the terminal voltage for /QON doesn't exceed AbsMax 7V if VBUS is selected at 13.5V and /QON is kept floating?

Best regards,
Kato

0 Joel Hernandez II over 5 years ago in reply to Sadanori Kato

TI__Mastermind 25800 points

Hey Kato,

So I just tested this on my bench and I will have to rescind my previous statement and discuss internally.

On the bench, the /QON pullup is definitely a function of either VBUS or VBAT, but there some clamping element internally. I will get back to you.

Regards,

Joel H

0 Joel Hernandez II over 5 years ago in reply to Joel Hernandez II

TI__Mastermind 25800 points

Hey Kato,

I will have to rescind my previous comments.

The pull-up voltage on /QON has two diode drops from VBUS or one diode drop from VBAT. The forward voltage of these diodes can be higher than 0.7V each.

Additionally, there is a 6V clamp on this rail, which means /QON will never be puled up beyond 6V.

Regards,

Joel H

0 Sadanori Kato over 5 years ago in reply to Joel Hernandez II

Guru 36530 points

Hi Joel-san,

Thank you for the detailed information.

I understand.

Best regards,
Kato

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BQ25601D: /QON Circuit