BQ25898CEVM-730: Output current limit and output gets reset

At which pin did you place the load?
Please read the GUI after you select "ENABLE OTG" and get 5V OTG output, check if there's any fault in the registers. Then apply the OTG load, read the GUI again when OTG output drops to 2.5V, check if there's any fault in the registers.
Thanks!

Hi Ning Tang,

I am connecting load to PMID pin (J2 on BQ25898EVM-730 board).

Load is 10E, 20W laod.

I checked the GUI for registers values. If I don't read the register, PMID voltage remains 5V after removing the load, but if I read register, the voltage reaches to only the battery voltage after load removal.

here are the snaps of registers for reference.

I also saw that Enable OTG gets unchecked every time I read registers, if I don;t read register, it remains checked.

Looking forward to your reply.

Hi,

Further to my last post, here are a few things I tried and issues I am currently facing.

I need a 5V output and hence trying to get output from OTG port. I am using only 1 battery (3.8V, 3050mAH) and no adapter for powering up the EVM.

I connected an LED to to this OTG USB port (this LED load must not be more than 10mA current) and it remained ON. 

Next, I connected a mobile phone (70% charged) and following was observed

         if I keep boost control voltage at 4.55V (irrespective of Boost current) the mobile charging starts. (it shows mobile is charging on mobile screen, did not see any change in battery level after around 5 minutes of charging with 2.1A boost output current)

         if I change boost control voltage to any value other than 4.55V (irrespective of Boost current) the mobile shows charging and it stops charging immediately within a second.

Next, I connected same phone but at 40% phone battery and saw following this time

         Even at 4.55V, the mobile starts charging and stops immediately. (at 70% battery this setup kept mobile charging continuously) 

When OTG voltage drops, "Enable OTG" pin gets cleared and I saw "Overlaod/OVP" in Boost Fault.

Here are the logs for reference. 

********** before connecting load to OTG*************

* Created: Mon Jan 22 17:35:55 IST 2018
*
* Format: Register Name tab Character,\t Hexadecimal register value.
* Device: bq24298
* BQZ Container: Charger_1_00-bq25898.bqz
*
Input Current Limit, HIZ and ILIM pin 7F
OTG Temperature thresholds, and Input Voltage DPM Offset E1
ADC controls, OTG Frequency, ICO, DCP, and Input Detection 00
Battery Load, WDT Reset periods, OTG and Charge Enable, and MINSYS setting AE
Fast Charge Current Limit settings and MTK Pump enable 20
Pre-charge and Termination Current Limit settings 1F
Charge Voltage Regulation Limit, Battery Low Voltage and Recharge threshold 5E
Termination Current Enable, STAT pin, WDT, Safety Timer, and JEITA Charge Current 04
IR Compensation and Thermal Regulation thresholds 03
ICO, Extended Safety Timer, BATFET control, MTK Pump Voltage, and JEITA Charge Voltage 00
OTG Regulation Voltage and Current Limit settings F0
Charger VBUS, Charging Mode, PG, USB Input, and System Voltage Regulation status 02
WDT, OTG/VBUS OVP, Thermal Shutdown, Safety Timer, and TS pin faults 00
Input Voltage DPM settings 12
Thermal Regulation Charge Status, and ADC Battery Voltage conversion 4B
ADC System Voltage conversion 4B
ADC TS pin voltage as percentage of REGN conversion 52
VBUS status, and ADC VBUS Voltage conversion 06
ADC Charge Current conversion 00
DPM status, and Input Current Limit setting 3F
Registers reset, Input Current Optimizer status, Device ID, and Temperature Profile 05

********** after connecting load to OTG*************

* Created: Mon Jan 22 17:46:15 IST 2018
*
* Format: Register Name tab Character,\t Hexadecimal register value.
* Device: bq24298
* BQZ Container: Charger_1_00-bq25898.bqz
*
Input Current Limit, HIZ and ILIM pin 7F
OTG Temperature thresholds, and Input Voltage DPM Offset E1
ADC controls, OTG Frequency, ICO, DCP, and Input Detection 00
Battery Load, WDT Reset periods, OTG and Charge Enable, and MINSYS setting 8E
Fast Charge Current Limit settings and MTK Pump enable 20
Pre-charge and Termination Current Limit settings 1F
Charge Voltage Regulation Limit, Battery Low Voltage and Recharge threshold 5E
Termination Current Enable, STAT pin, WDT, Safety Timer, and JEITA Charge Current 04
IR Compensation and Thermal Regulation thresholds 03
ICO, Extended Safety Timer, BATFET control, MTK Pump Voltage, and JEITA Charge Voltage 00
OTG Regulation Voltage and Current Limit settings F7
Charger VBUS, Charging Mode, PG, USB Input, and System Voltage Regulation status 02
WDT, OTG/VBUS OVP, Thermal Shutdown, Safety Timer, and TS pin faults 40
Input Voltage DPM settings 0D
Thermal Regulation Charge Status, and ADC Battery Voltage conversion 4B
ADC System Voltage conversion 4B
ADC TS pin voltage as percentage of REGN conversion 52
VBUS status, and ADC VBUS Voltage conversion 06
ADC Charge Current conversion 00
DPM status, and Input Current Limit setting 3F
Registers reset, Input Current Optimizer status, Device ID, and Temperature Profile 05

1) For your GUI setup, it only shows the register values when you click "read register". The register values will not be automatically updated with the current register values. For the 5V PMID GUI picture, VBUS status shows "No Input", but at the time the device should be in OTG mode, so please click "read register" again to refresh the register values after selecting "Enable OTG" and observe 5V at PMID. At this time, VBUS status should be read as "OTG" (REG0B[7:5]=111).
2) After connecting a load to PMID, click "read register" again. Check if VBUS status is "OTG" or not and if there are any faults.
Please note that REG0C is a fault register. It keeps all the fault information from last read until the host issues a new read. For example, if Charge Safety Timer Expiration fault occurs but recovers later, the fault register REG0C reports the fault when it is read the first time, but returns to normal when it is read the second time. In order to get the fault information at present, the host has to read REG0C for the second time...
3) It is possible that connecting the PMID load introduces some overshoots and cause Boost Fault. Once that happens, the device will exit the OTG mode automatically.
4) Are you evaluating bq25898 or bq25898C? bq25898C does not support OTG.
Thanks!

Hi Ning Tang,

I would try your suggestions today and will let you know of the outcomes, however I would like to ask

1. Why should we connect a load to PMID pin? Is PMID the pin for supplying power to the external circuit? Is it OK to connect load at VBUS/OTG port?

2. If Boost Fault register fails (Overload/OVP), will it cause device to exit OTG mode? And if it  recovers from it automatically, will the device re-enter the OTG Mode?

3. I did not connected any load to PMID, but on OTG supply pin. Will connecting a load to OTG which introduces overshoots ( I connected a mobile phone which I believe should not cause any overshoots but still) can cause exit from OTG Mode?

I am using BQ25898EVM-730, I am able to see OTG voltage without any load connected, it gets affected as soon as I connects a load to OTG/VBUS pins.

Hi,

We tried multiple thing as suggested by you and took help of our local TI support as well but are unable to make this work.

The IC shuts down at even 100E resistance. (We tried resistance box, 1000E to 500E it is ON, after 500E the performance is not consistent, sometime it remains ON for shorter time, some times for longer time but on 100E load, it shuts down at shortest time, around 5 minutes).

We are unable to get the EVM working as described. 

Please help us in returning this as well as EV2300 (We had to purchase an EV2300 in order to get this working) that we purchased to make this work.

Could you please get another brand new EVM and try again following the EVM User's guide?

Thanks!

Dear Ning Tang,

We already followed the guidelines on a brand new EVM, it did not worked. We have passed our timelines for this evaluation. Please advice on how to return these items.

Dear TI Team,

Since our board has not worked with desired results, we request an approval to return our boards (BQ25898EVM-730 and EV2300).

Hi,

Please initiate RMA for EV2300 board as well, as this was purchased only for BQ258988EVM support.

Dear TI Team,

Please update on RMA for EV2300. We are planning to ship these items and would appreciate a prompt update on this.