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BQ24297: Question about adapter detection of BQ24297

Chase Jeong
Mastermind 6040 points
Part Number: BQ24297

Tool/software:

Dear TI experts,

My customer found the issue about adapter detection using BQ24297. Please see the detailed description below.

1. First I attach the schematic for your convenience.

8750.sch1.pdf

2. They use 4 lines USB A-to-C cable. (Device side is type C, and adapter(or laptop USB) side is type A.)

3. When R82 and R83 is attached (D+ and D- is connected)

3-1. tested PD adapter, Samsung adapter, Normal 5V/1A adapter, 2 different power banks are connected to VBUS => charged as 950mA current.

3-2. tested Apple adapter, DC Power supply(using only VCC and GND, not using D+ and D-) => charged as 450mA current, but sometimes charged as 950mA current. (I don't know why yet.)

3-3. tested connecting VBUS to laptop USB (Samsung, LG) using 4 lines A-to-C cable => not charged, still 5V is present. STAT pin is high. (charging is complete even not completed battery charging)

3-4. tested connecting VBUS to laptop USB (Samsung, LG) using 2 lines A-to-C cable (only 5V and GND) => charged as 950mA current.

4. When R82 and R83 is not attached (D+ and D- is not connected)

4-1. tested PD adapter, Samsung adapter, Normal 5V/1A adapter, 2 different power banks are connected to VBUS (both using 2 lines A-to-C cable and 4 lines A-to-C cable) => charged as 450mA current. but sometimes charged as 950mA current. (I don't know why yet.)

4-2. tested connecting VBUS to laptop USB (Samsung, LG) (both using 2 lines A-to-C cable and 4 lines A-to-C cable) => charged as 450mA current.

(** 2 lines A-to-C cable is which D+/D- shorted on device side.)

Anyway My customer have a question especially about the result of 3-3 and 3-4.

Could you check the possibility of each scenarios are right or not?

And please let me know if you need more information about it.

Best regards,

Chase

  • +1
    TI__Mastermind 27155 points

    Hi Chase, 

    I am checking on all the scenarios mentioned and will get back to you with an update in the next day or two. Thank you for your patience. 

    Best Regards,

    Garrett 

  • +1 in reply to Garrett Kreger
    TI__Mastermind 27155 points

    Hi Chase, 

    Please see my comments below. 

    Chase Jeong said:
    3-2. tested Apple adapter, DC Power supply(using only VCC and GND, not using D+ and D-) => charged as 450mA current, but sometimes charged as 950mA current. (I don't know why yet.)

    For the case of D+/D- not connected charging at 450mA matches expectation because the BQ24297 will detect the input as "unknown" and set input current limit to 500mA. I would need to review register values for the charging at 950mA case. Input current limit of 500mA is also expected for all 4-x cases where D+/D- is not connected. 

    Chase Jeong said:
    3-3. tested connecting VBUS to laptop USB (Samsung, LG) using 4 lines A-to-C cable => not charged, still 5V is present. STAT pin is high. (charging is complete even not completed battery charging)

    Can you please help to share a register dump for this case? It is not expected for a certain input detection to result in not charging. Has the customer confirmed they are not disabling charge in some way? 

    Chase Jeong said:
    3-4. tested connecting VBUS to laptop USB (Samsung, LG) using 2 lines A-to-C cable (only 5V and GND) => charged as 950mA current.

    For this case please share a register dump and a waveform showing D+/D- pins of the BQ24297 at the time of input connection.  

    Best Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    Mastermind 6040 points

    Dear Garrett,

    Thank you for your great support.

    first of all, 2 lines A-to-C cable is shorted between D+ and D- lines, so if I use this cable BQ24297 will recognize the adapter as CDP. So all the cases of using 2 lines A-to-C cable (including case 3-4) are correct.

    And case 3-3 is still the problem, I asked the register dump to my customer. I will get the feedback asap.

    Also I requested register dump of case 4-1. Also I will get the feedback asap.

    Best regards,

    Chase 

  • 0 in reply to Chase Jeong
    Mastermind 6040 points

    Dear Garrett,

    Here are the updates about register dumps.

    1. R82 and R83 is attached (D+ and D- is connected), using 4 lines A-to-C cable, connecting to PC USB 3.0 => 5V is present but not charging

    REG00 0x A0
    REG01 0x 1A
    REG02 0x 1C
    REG03 0x 11
    REG04 0x B0
    REG05 0x 8C
    REG06 0x 73
    REG07 0x 4B
    REG08 0x 0
    REG09 0x 0
    REG10 0x 60

    2. 10 seconds passed after case 1, STAT pin goes to high and charging complete indicated.

    REG00 0x A0
    REG01 0x 1A
    REG02 0x 1C
    REG03 0x 11
    REG04 0x B0
    REG05 0x 8C
    REG06 0x 73
    REG07 0x 4B
    REG08 0x 44
    REG09 0x 0
    REG10 0x 60

    3. R82 and R83 is not attached (D+ and D- is not connected), using 4 lines A-to-C cable, connecting to PD adapter,Samsung adapter,5V/1A adapter => 450mA charging detected.

    REG00 0x 22
    REG01 0x 1A
    REG02 0x 1C
    REG03 0x 11
    REG04 0x B0
    REG05 0x 8C
    REG06 0x 73
    REG07 0x 4B
    REG08 0x 2C
    REG09 0x 0
    REG10 0x 60

    4. R82 and R83 is not attached (D+ and D- is not connected), using 4 lines A-to-C cable, connecting to PD adapter,Samsung adapter,5V/1A adapter => Sometimes 950mA charging detected.

    REG00 0x 26
    REG01 0x 1A
    REG02 0x 1C
    REG03 0x 11
    REG04 0x B0
    REG05 0x 8C
    REG06 0x 73
    REG07 0x 4B
    REG08 0x A4
    REG09 0x 0
    REG10 0x 60

    Customer's initial register setting of is as below;

    charger_setup(0x00, 0x25);
    charger_setup(0x01, 0x1A);
    charger_setup(0x02, 0x1C);
    charger_setup(0x03, 0x11);
    charger_setup(0x04, 0xB0);
    charger_setup(0x05, 0x8C);
    charger_setup(0x06, 0x73);
    charger_setup(0x07, 0xCB);
    charger_setup(0x08, 0xB4);
    charger_setup(0x09, 0x80);
    charger_setup(0x0A, 0x60);

    My first question is, why the setting of REG00 is changing. (Is it possible?)

    Second, I think only SDP detection is not working as I expected. Hope these register setting is helpful for debug.

    And final question from my customer.

    - What is the exact purpose of Input Voltage Limit of REG00? Does it limit the voltage which is connected to VBUS?

    If so, what is the meaning of default setting? the charger only accept 4.35V even 5V is applied to VBUS?

    what is the benefit from charger's point of view in ths case?

    Please check these issues. Thanks.

    Best regards,

    Chase

  • 0 in reply to Chase Jeong
    Mastermind 6040 points

    Dear Garrett,

    Good news - My customer found the reason of cannot detecting SDP ; OTG pin in the schematic is floating.

    After they apply high to OTG pin, 500mA charging current is applied.

    And here are the last questions;

    1. Can BQ24297 recognize USB 2.0 and USB 3.0 itself? Because supplying current is the same when connecting USB 2.0 port and USB 3.0 port even OTG pin is high.

    2. What is the exact purpose of "Input Voltage Limit" in REG00? I thought that it is for preventing supply voltage (input voltage to charger) drop if the current consumption is exceeded the limit of power source.

    Actually I saw that supplying voltage from USB 2.0 is dropped to 4.6V to get more charging current. If I set "Input Voltage Limit" to 5V, Can I prevent the voltage drop like the situation before?

    Please check this issue. Thanks.

    Best regards,

    Chase

  • +1 in reply to Chase Jeong
    TI__Mastermind 27155 points

    Hi Chase, 

    Please see my comments below. 

    Great to hear the customer sees expected 500mA for SDP with OTG pulled high. 

    1)The BQ24297 datasheet states the following in section 5 "The device is compliant with USB 2.0 and USB 3.0 power specifications with input current and voltage regulation." The tables in section 9.3.1.3.4 show the device does not have the ability to set input current limit to 900mA on its own, so unfortunately it is not able to determine when an input is rated for up to 900mA. 

    2)The BQ24297 has both an input current limit and an input voltage limit. The input voltage limit is a lower limit and its purpose is to reduce the charge current if the BQ24297 detects the input voltage falling due to being over-loaded. We typically recommend you set the input voltage limit to some value below your expected input voltage of 5V, hence why the default is 4.36V. 

    I would not recommend setting input voltage limit to 5V with a 5V input, but you can set it higher than 4.36V to prevent significant voltage drop. 

    Best Regards,

    Garrett 

  • +1 in reply to Garrett Kreger
    TI__Mastermind 27155 points

    Hi Chase, 

    Upon review of the register logs I have the following comments. 

    For case 1) REG00 bit 7 is set to 1 to enable HIZ state. This appears to be what is preventing charging. I have two suggestions: 1. please have MCU host attempt to write REG00[7] = 0 2. ensure OTG is pulled high so input current limit is set to 500mA rather than 100mA. 

    Case 3) appears to be expected detection considering D+ and D- are not connected. 

    For case 4) BQ24297 is detecting a non standard adapter and input current limit is set to 2A. Higher current charging is expected when input current limit is set higher. Please have the customer double check if D+ and D- are in fact not connected. 

    Best Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    Mastermind 6040 points

    Dear Garrett,

    The issue is closed. Thank you for your great support.

    Best regards,

    Chase