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BQ76930EVM: Some problems foe using BQ76930EVM

Chih wei Huang
Prodigy 50 points
Part Number: BQ76930EVM
Other Parts Discussed in Thread: BQ76930, BQ78350-R1, BQSTUDIO, BQ78350, BQ76200

Hi All :

I have some problems for testing by BQ76930EVM and please help to advide it ,thanks.

1. I  mesaure the power consumption by by BQ76930EVM (Remove Electronic load) and  current is about 15mA~20mA for normal mode.

   Is it correct ?  It has big gap with IC spec (650uA) and why is root cause ?

 

2. How do I mesaure to meet spec (about 650uA)  for power consumption ? 

 

3. Does the protection setting of bq76930 will update from bq78350- R1 automatically when the bq78350-R1 and bq76930 are wake up ?

    If not , how do I change the setting of bq76930 by bq78350- R1 bqstudio ?


4. Could you help to explain the setting that 4.3V is 0x09C for BQ76930 OV_TRIP?

 

5. How do I sent the command to let bq76930 shutdown by BQ78350-R1 bqstudio? Could you provide the example to us reference ?



 

  • 0
    TI__Guru 54715 points

    Hi Chih,

    1. The BQ76930 supply current for the data sheet is the supply current for the IC without load current from REGOUT or the FET outputs.  The BQ76930EVM also includes the resistor divider to simulate cell voltages which uses 200 ohm resistors for each cell at 4V/cell the current for the cell simulator is 4V/200 = 20 mA. 

    2. To measure the current in the BQ76930 measure the voltage across the supply filter resistor and divide by the resistance. The EVM also has 100 ohm shunt resistors in the BAT power pins, 100 ohms takes more thought than 1k ohm, but the test points may be easier to probe.  For REGSRC measure and calculate similarly.  You can remove the BQ78350-R1 current by disconnecting it at the shunts.  FETs may be turned off, measure with no communication.

    3. When operated with the BQ78350, the BQ78350 makes all register settings for the BQ76930 when it boots up and periodically afterward.  To change the values change the voltage settings in the BQ78350 data memory.  It is a flash memory and will be remembered on the next power cycle.  Only over current protection requires calculation and reference to the BQ76930 data sheet to select the register value as the BQ78350 just passes those values on to the BQ76930.

    4. See the BQ76930 data sheet section 10.3.1.2.1 Integrated Hardware Protections.  The 0x09C becomes 0x2098 and is calculated as shown.

    5. In BQStudio send the "SHUTDOWN" command, typically 6th in the list on the right side.

  • 0 in reply to WM5295
    Prodigy 50 points

    Hi All :

    If I want to measure the power consumption by BQ76930EVM , could you help to provide method of mesaurement steps to us reference ?

    In addition , what is the the reasonable value of power consumption for BQ76930 and B76200 design?

  • 0 in reply to Chih wei Huang
    TI__Guru 54715 points

    Hi Chih,

    To measure current consumption of the application circuit separate from the test circuit on the BQ76930EVM, provide a cell simulator resistor divider external to the board and connect it to the board, open the on-board cell simulator switches.  Measure the current into the board, this will represent the circuit current including:

    BQ76930 current

    FET load current, will vary with FET state

    Thermistor currents if external temperature sensing is used, will be a pulsed current.

    Gauge or MCU load current on REGOUT.  Note this may vary with operation.

    To add current for the BQ76200, look at the data sheet current and add an estimation for load current x5 due to the charge pump efficiency.  So if you have 2.4 uA of load, add  12 uA.