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BQ25895: when the battery doesn't exist,the SYS Pin loaded with 2A without output.

john xiao
Intellectual 470 points
Part Number: BQ25895

Dear all:

I use  5V/3A  adapter connected to bq25895EVM-664 test when the battery does't exist,the SYS Pin loaded with 2A without output.the register configuration isBQ25895 battery doesn't exist.zip

I want to know how to set up BQ25895 hardware and software ensure the SYS Pin is loaded with 2A stable output.thanks a lot.

  • 0
    TI__Guru**** 166176 points
    Hi John,

    Are the register settings from the charge with the 2A load applied? I am going to assume not. From the register configuration, I notice that the Watchdog timer is set to 40 seconds. Are you writing to the watchdog timer to keep your register settings? If not, ILIM pin will be auto re-enabled after 40 seconds which could be clamping your input current. What is the voltage as measured at the VBUS pin when you apply the 2A load at SYS? If you disable OTG mode, does the SYS output maintain regulation?
  • 0 in reply to Jeff F
    Intellectual 470 points

    Hi Jeff:

    I had disable the Watchdog timer ,set  Enable ILIM pin bit is 0 and Enable OTG bit is 0.this is charged register Settings

    Fullscreen BQ25895 battery doesn't exist-1.txt Download 
    * Created: Wed Apr 25 15:02:30 CST 2018
*
* Format: Register Name  tab Character,\t  Hexadecimal register value.
* Device: bq25890
* BQZ Container: Charger_1_00-bq25890_895.bqz
*
Input Current Limit, HIZ and ILIM pin	3F
OTG Temperature thresholds, and Input Voltage DPM Offset	05
ADC controls, OTG Frequency, ICO, DCP, and Input Detection	3D
Battery Load, WDT Reset periods, OTG and Charge Enable, and MINSYS setting	4A
Fast Charge Current Limit settings and MTK Pump enable	20
Pre-charge and Termination Current Limit settings	13
Charge Voltage Regulation Limit, Battery Low Voltage and Recharge threshold	5E
Termination Current Enable, STAT pin, WDT, Safety Timer, and JEITA Charge Current	8D
IR Compensation and Thermal Regulation thresholds	03
ICO, Extended Safety Timer, BATFET control, MTK Pump Voltage, and JEITA Charge Voltage	44
OTG Regulation Voltage and Current Limit settings	93
Charger VBUS, Charging Mode, PG, USB Input, and System Voltage Regulation status	A7
WDT, OTG/VBUS OVP, Thermal Shutdown, Safety Timer, and TS pin faults	00
Input Voltage DPM settings	1A
Thermal Regulation Charge Status, and ADC Battery Voltage conversion	00
ADC System Voltage conversion	00
ADC TS pin voltage as percentage of REGN conversion	00
VBUS status, and ADC VBUS Voltage conversion	9F
ADC Charge Current conversion	00
DPM status, and Input Current Limit setting	3F
Registers reset, Input Current Optimizer status, Device ID, and Temperature Profile	39

    I measured the VBUS voltage is 5.1V when apply the 2A load at SYS.but the SYS output still 0.does BQ25895 SYS pin do not on load output when the battery does not exist?

  • 0 in reply to john xiao
    TI__Guru**** 166176 points

    HI John,

    When the battery is attached, is the IC switching (i.e. is there a square wave at SW)?  When battery is not attached, does SW look the same?