• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 2 answers
  • Subscribers 62 subscribers
  • Views 450 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ25731: About VAP /OTG /FRS Configuration Comparison

Tsukui Yusuke
Guru 21930 points
Part Number: BQ25731

Hi,

Data sheet describes "VAP / OTG / FRS Configuration Comparison".
Let me ask you two questions about the table below.

1.The CHARGER STATUS of CASE1 and CASE5 is same.
   Could you give me an example of the difference between CASE1 and CASE5 and how to use them properly?

2.The CHARGER STATUS of CASE2 and CASE3 is same.
   Could you give me an example of the difference between CASE2 and CASE3 and how to use them properly?



Regards,
Yusuke

  • 0
    TI__Genius 11850 points

    Hi Yusuke,

     

    The table is providing examples to show the conditions which can cause OTG and FRS to be enabled/disabled.

     

    1) Case #1 and case #5 both have only a battery connected (no adapter). The difference between the two cases is the way in which OTG mode is disabled. In case #1, the charger is not in OTG mode because the OTG/VAP/FRS pin is low. In case #5, even though the OTG/VAP/FRS pin is pulled high, the charger is still not in OTG mode because the EN_OTG bit = 0.

     

    2) The difference between case #2 and case #3 is the reason that FRS is disabled. In case #2, FRS is disabled because the OTG_VAP_MODE bit = 0. In case #3, even though the OTG_VAP_MODE bit is correctly set to 1, FRS is still disabled because the EN_FRS bit = 0.

     

    Best regards,

    Angelo

  • 0 in reply to Angelo Zhang87
    Guru 21930 points

    Hi Angelo,

    Thank you for your reply.
    I understand that there are two ways to disable each.

    ・EN_OTG bit = 0 vs  OTG/VAP/FRS pin is low
    ・EN_FRS bit = 0 vs   OTG_VAP_MODE bit is correctly set to 1

    How should I use the disable method properly?
    Which is better, using the EN_OTG(EN_FRS) bit or the OTG / VAP / FRS pin?

    Best regards,
    Yusuke

  • 0 in reply to Tsukui Yusuke
    TI__Genius 11850 points

    Hi Yusuke,

     

    It is not recommended to change the OTG_VAP_MODE and EN_FRS bits after the OTG/VAP/FRS pin has already been pulled high, as described in Section 9.3.3 of the datasheet. Regarding FRS, I suggest pulling the OTG/VAP/FRS pin low, then setting the bits appropriately, and finally pulling the OTG/VAP/FRS pin high again when you wish to re-enable FRS.

     

    Regarding OTG mode, the EN_OTG bit is more lenient. As discussed in the previous paragraph, you can pull the OTG/VAP/FRS pin low or high to disable or enable OTG mode. Alternatively, if the OTG/VAP/FRS pin is already pulled high and the OTG_VAP_MODE bit is already a 1, then you can write to the EN_OTG bit in order to disable or enable OTG mode. Either way is fine.

     

    Best regards,

    Angelo

  • 0 in reply to Angelo Zhang87
    Guru 21930 points

    Hi Angelo,

    Thank you for your kind support.
    Let me ask you another question about case1.
    If EN_OTG bit is set to 1 in case1, does OTG/VAP/FRS pin pin setting take precedence?

    Best regards,
    Yusuke

  • +1 in reply to Tsukui Yusuke
    TI__Genius 11850 points

    Hi Yusuke,

     

    Your understanding is correct. If the EN_OTG bit is set to 1 in case #1, the charger status will not change. The BQ25731 will not enter OTG mode because the OTG/VAP/FRS pin is low.

     

    'X' in Table 9-1 indicates a "don't care" condition. In other words, for case #1, since the OTG/VAP/FRS pin is low, it doesn’t matter whether EN_OTG is 0 or 1. The charger status will not change because the OTG/VAP/FRS pin takes precedence.

     

    Best regards,

    Angelo