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BQ25720EVM: VSYS drop issue

Allen Lin
Intellectual 2810 points
Part Number: BQ25720EVM
Other Parts Discussed in Thread: BQ25720

Tool/software:

Hi, Expert

I'm testing BQ25720 as following setup, but VSYS always drop when heavy load.

Test condition:

Vin=20V;

VSYS_min=12.3V

ISYS=0A to 6A;

IBAT=0A;

JP3=4S;

Test result:

VSYS(V) ISYS(A)
12.43

0
12.28

1
12.28

2
12.27

3
12.26

4
11.71

5
9.64

6

As you can see, when ISYS increase to 6A, VSYS drop to 9.64V. Does it reach any protect threshold? Or I have to change any setting to solve this issue?

Please check attached register file for reference. Thanks.   

Fullscreen 12.3Vo_register.txt Download 
* Created: Fri Sep 20 18:26:31 CST 2024
*
* Format: Register Name  tab Character,\t  Hexadecimal register value.
* Device: bq25720
* BQZ Container: Charger_1_00-BQ25720.bqz
*
Charge Option 0	E70E
Charge Current	0000
Max Charge Voltage	41A0
OTG Voltage	09C4
OTG Current	3C00
Input Voltage	1E00
Min System Voltage	7B00
IIN_HOST	4100
Charger Status	8000
Prochot Status	B800
IIN_DPM	4100
ADC VBUS and PSYS	7F00
ADC IBAT	0000
ADC IIN and CMPIN	0000
ADC VSYS and VBAT	0000
Manufacture ID	0040
Device ID	00E1
Charge Option 1	3300
Charge Option 2	00B7
Charge Option 3	0434
Prochot Option 0	4A81
Prochot Option 1	41A0
ADC Option	2000
Charge Option 4	0048
Vmin Active Protection	006C

  • 0
    TI__Mastermind 32861 points

    Hello Allen,

    I think this issue is related to power requirement.

    You have an Input current limit of 3250:

    Input power:65W

    Output power:57.84W

    your feficiency is aound 89%, the expected efficiency is around 90-95%.(This could be related to the way the power is measured)

    I recommend increasing the input power to support the output power.

    Best Regards,

    Christian.

  • 0 in reply to Christian Moyer
    TI__Intellectual 2810 points

    Hi Christian,

    Thanks for your reply.

    I increased Input current limit to 6350mA. (Power supply is GPC-3060D which can support 6A) 

    But still found that when ISYS increasing and input current near 3A, Charger status IN_IIN_DPM would change to "In IINDPM" and VSYS drop.

    Test condition:

    Vin= 5V;

    VSYS_min=12.3V

    IBAT=0A;

    JP3=4S;

    ISYS=0.96A (Not in IINDPM)   

    ISYS=1.06A (In IINDPM)

    Please check attached register file and help me to understand what issue happens. 

    Thanks.

    Best regards,

    Allen

    Fullscreen 12.3Vo_0.96A.txt Download 
    * Created: Tue Sep 24 19:01:22 CST 2024
*
* Format: Register Name  tab Character,\t  Hexadecimal register value.
* Device: bq25720
* BQZ Container: Charger_1_00-BQ25720.bqz
*
Charge Option 0	E70E
Charge Current	0000
Max Charge Voltage	41A0
OTG Voltage	09C4
OTG Current	3C00
Input Voltage	0180
Min System Voltage	7B00
IIN_HOST	7F00
Charger Status	8000
Prochot Status	B800
IIN_DPM	7F00
ADC VBUS and PSYS	3300
ADC IBAT	0000
ADC IIN and CMPIN	0000
ADC VSYS and VBAT	0000
Manufacture ID	0040
Device ID	00E1
Charge Option 1	3300
Charge Option 2	00B7
Charge Option 3	0434
Prochot Option 0	4A81
Prochot Option 1	41A0
ADC Option	2000
Charge Option 4	0048
Vmin Active Protection	006C

    Fullscreen 12.3Vo_1.06A.txt Download 
    * Created: Tue Sep 24 19:02:31 CST 2024
*
* Format: Register Name  tab Character,\t  Hexadecimal register value.
* Device: bq25720
* BQZ Container: Charger_1_00-BQ25720.bqz
*
Charge Option 0	E70E
Charge Current	0000
Max Charge Voltage	41A0
OTG Voltage	09C4
OTG Current	3C00
Input Voltage	0180
Min System Voltage	7B00
IIN_HOST	7F00
Charger Status	8800
Prochot Status	B800
IIN_DPM	7F00
ADC VBUS and PSYS	3300
ADC IBAT	0000
ADC IIN and CMPIN	0000
ADC VSYS and VBAT	0000
Manufacture ID	0040
Device ID	00E1
Charge Option 1	3300
Charge Option 2	00B7
Charge Option 3	0434
Prochot Option 0	4A81
Prochot Option 1	41A0
ADC Option	2000
Charge Option 4	0048
Vmin Active Protection	006C
       

  • 0 in reply to Allen Lin
    TI__Mastermind 32861 points

    Hello Allen,

    Can you enable all of the ADC and recollect the two test setups?

    Best Regards,

    Christian.

  • 0 in reply to Christian Moyer
    TI__Intellectual 2810 points

    Hi Christian,

    I enabled all of ADC and found that Input current read back would be clamped at 2950mA when charger status "In IINDPM".

    So I disable EN_IIN_DPM let input current wouldn't be clamped, it works also solved VSYS drop issue but I still want to know why IIN_DPM was trigger at 2950mA even increase IIN_HOST to 6350mA? 

    Attached register file for reference. Thanks.

    Test condition:

    Vin= 5V;

    VSYS_min=12.3V

    IBAT=0A;

    JP3=4S;

    ISYS=1.1A (Not in IINDPM)   

    Fullscreen 12.3Vo_1.1A.txt Download 
    * Created: Wed Sep 25 19:14:54 CST 2024
*
* Format: Register Name  tab Character,\t  Hexadecimal register value.
* Device: bq25720
* BQZ Container: Charger_1_00-BQ25720.bqz
*
Charge Option 0	E70E
Charge Current	0000
Max Charge Voltage	41A0
OTG Voltage	09C4
OTG Current	3C00
Input Voltage	0180
Min System Voltage	7B00
IIN_HOST	7F00
Charger Status	8000
Prochot Status	B800
IIN_DPM	7F00
ADC VBUS and PSYS	3300
ADC IBAT	0000
ADC IIN and CMPIN	3924
ADC VSYS and VBAT	9400
Manufacture ID	0040
Device ID	00E1
Charge Option 1	3300
Charge Option 2	00B7
Charge Option 3	0434
Prochot Option 0	4A81
Prochot Option 1	41A0
ADC Option	A0FF
Charge Option 4	0048
Vmin Active Protection	006C

    ISYS=1.2A (In IINDPM)

    Fullscreen 12.3Vo_1.2A.txt Download 
    * Created: Wed Sep 25 19:16:34 CST 2024
*
* Format: Register Name  tab Character,\t  Hexadecimal register value.
* Device: bq25720
* BQZ Container: Charger_1_00-BQ25720.bqz
*
Charge Option 0	E70E
Charge Current	0000
Max Charge Voltage	41A0
OTG Voltage	09C4
OTG Current	3C00
Input Voltage	0180
Min System Voltage	7B00
IIN_HOST	7F00
Charger Status	8800
Prochot Status	B800
IIN_DPM	7F00
ADC VBUS and PSYS	3300
ADC IBAT	0000
ADC IIN and CMPIN	3B24
ADC VSYS and VBAT	8A00
Manufacture ID	0040
Device ID	00E1
Charge Option 1	3300
Charge Option 2	00B7
Charge Option 3	0434
Prochot Option 0	4A81
Prochot Option 1	41A0
ADC Option	A0FF
Charge Option 4	0048
Vmin Active Protection	006C

    ISYS=1.2A (Disable EN_IIN_DPM)

    Fullscreen 12.3Vo_1.2A_IINDPM Disable.txt Download 
    * Created: Wed Sep 25 19:19:24 CST 2024
*
* Format: Register Name  tab Character,\t  Hexadecimal register value.
* Device: bq25720
* BQZ Container: Charger_1_00-BQ25720.bqz
*
Charge Option 0	E70C
Charge Current	0000
Max Charge Voltage	41A0
OTG Voltage	09C4
OTG Current	3C00
Input Voltage	0180
Min System Voltage	7B00
IIN_HOST	7F00
Charger Status	8000
Prochot Status	B800
IIN_DPM	7F00
ADC VBUS and PSYS	3300
ADC IBAT	0000
ADC IIN and CMPIN	3E24
ADC VSYS and VBAT	9400
Manufacture ID	0040
Device ID	00E1
Charge Option 1	3300
Charge Option 2	00B7
Charge Option 3	0434
Prochot Option 0	4A81
Prochot Option 1	41A0
ADC Option	A0FF
Charge Option 4	0048
Vmin Active Protection	006C

    Best regards,

    Allen

  • 0 in reply to Allen Lin
    TI__Mastermind 32861 points

    Hello Allen,

    You have EN_EXTLIM enabled.

    When this is enabled the input current limit is set by the lower value of ILIM_HIZ pin and IIN_DPM register. The ILIM_HIZ pin is limited to around 3A on the EVM. If you disable this bit the charger should only rely on the input current limit set in the register.

    Best Regards,

    Christian.