BQ25703A: Clarification on Charger features

VENKATAPPA SACHIN

Part Number: BQ25703A

Hi,

Need Clarification:
1) When Charger Status (I2C Addr = 21H/20H) register gets updated ?
2) Does CHRG_OK notifies HOST whenever USBC Charger inserted/removed ?
3) After Enabling Charging in ChargeOption1 (I2C Addr = 0H/1H) register, why should we periodically update WatchDog timer to continue Charging ?
4) When does Charger does "Charge Termination" ?
5) Does this chip supports "CE (Charge Enable/Disable)" feature ?
6) Implementation guide available ?

Thanks.

over 6 years ago

0 Joel Hernandez II over 6 years ago

TI__Mastermind 25800 points

Hey Venkatappa,

For 1) Table 19 and Table 20 of the datasheet describe the Faults and Statuses that are updated whenever those particular events occur. And Status bit will be immediately updated, while faults are latched until they are read at least once.

For 2) Yes. This pin notes when a valid input source has been applied to VBUS. An input UVLO or OVP event will pull this pin LOW. You can refer to section 8.3.2.1 CHRG_OK Indicator of the datasheet for more details on the CHRG_OK indication pin.

For 3) The watchdog timer will reset the charging current the 0mA. This is a safety function in the event the host has latched up or no longer can control the charger. Effectively, if the host cannot reset the watchdog timer, there is likely an error with the host, and charging should be stopped. You may disable the Watchdog Timer in ChargeOption0 in order to disable the function.

For 4) This charge controller does not terminate charge. This must be handled by the host.

For 5) Charge can be enabled or disabled using the Charge Inhibit bit in ChargeOption0.

For 6) I will first point you to the EVM User Guide as a first pass guide for implementing this charger in a design. http://www.ti.com/lit/ug/sluubg6/sluubg6.pdf

Regards,

Joel H

0 VENKATAPPA SACHIN over 6 years ago in reply to Joel Hernandez II

Intellectual 350 points

Thanks Joel for clarification.

One question:

<Joel> For 1) Table 19 and Table 20 of the datasheet describe the Faults and Statuses that are updated whenever those particular events occur. And Status bit will be immediately updated, while faults are latched until they are read at least once.

Ok got to know when they gets updated. How Host will come to know about this change ? Does Host has to poll the status register periodically ? or is there any alert/interrupt mechanism available? Please clarify.

<Joel> For 3) The watchdog timer will reset the charging current the 0mA. This is a safety function in the event the host has latched up or no longer can control the charger. Effectively, if the host cannot reset the watchdog timer, there is likely an error with the host, and charging should be stopped. You may disable the Watchdog Timer in ChargeOption0 in order to disable the function.

Thanks. On Watchdog timer expiry, does BQ charger notifies Host ? Or Host should poll ?

0 Joel Hernandez II over 6 years ago in reply to VENKATAPPA SACHIN

TI__Mastermind 25800 points

Hey Venkatappa,

Most of the faults do not have a flag to the host. The host would have to periodically read the charger to verify if a fault is present. Typically, the faults will manifest in several ways; either the converter stopping completely or no charging.

For the Watchdog timer, the Host should poll.