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BQ77915EVM-014 :I purchased a BQ77915EVM-014 and tested it, but it malfunctioned.

Part Number: BQ77915EVM-014

Below is the order in which I conducted the experiment, but if there is anything wrong, please let me know. If not, please let me know if the module is defective.

 

 

 

Perform charging and discharge tests using BQ77915EVM-014 and BQ24170EVM

 

It used six 3,000mAh lithium-ion batteries to form 11.1 V, 6,000mAh battery packs.

Two lithium-ion batteries are connected in parallel per single BMS cell and the BMS module is used as a 3-cell base.

 

Based on the manual, the charging test was carried out by applying 11.1V to the cell and 12.6V to the output using SMPS.

Discharge test was performed by applying 11.1 V to the cell and connecting 5kΩ resistance to the output.

The maximum output current is composed of 10 A by parallelizing the 0.01Ω resistance to the SRN resistance (0.015Ω) of the BQ77915EVM-014.

The battery pack is connected (two parallels per cell, voltage per cell is 4V, 4V and 3.9V respectively), DSG/CHG FET off (non-chargeable).

Based on the data sheet's Fault Operation, we used a multimeter, oscilloscope to find the cause, but there was no match.

While trying this and that method, the battery voltage was unified to 3.9V and connected to BMS, and it became DSG/CHG FET on.

The battery pack was charged using the BQ24170EVM and the BQ77915EVM-014 (full charge voltage 12.45V).

After charging, cell balancing was confirmed to be activated.

After cell balancing ended, DSG/CHG FET was turned off and charging and discharging became impossible.

After that, DSG/CHG FET is not turned on by any method.

Override of FET with CTRC/CTRD pin does not turn on.

After that, even if you test using SMPS, FET is not turned on.

The voltage of test point1 (7.5V) was applied to the gate of the DSG/CHG FET to force the FET on, charge and discharge tests were conducted.

Cell balancing was not activated when charging and after charging.

After the charge ends, the cell voltages are 4.08V, 4.25V and 4.24V respectively.

 

The BQ24170EVM was operated normally. It worked normally when charging a single-cell battery and charging a three-cell battery. However, the DSG/CHG FET of the BQ77915EVM-014 was continuously off and the test could not be carried out.

All shunt is correctly connected.

 

  • Hi KyungHoon,

    It is always disappointing when something goes wrong in evaluation.

    You have checked all shunts, so the only choice would seem to replace the part.  You may want to check further for other damage.

    Check the PRES shunt at J4 pins 2-3 and confirm it is getting the battery voltage.  If in question check solder and the voltage at the IC pin.

    Check that the VDD is reaching the IC pin VDD..  It should match TP1.

    Check that AVDD has voltage at J8  pin 3.  

    Check that CCFG is low, J8 pins 1-2.

    Check the voltage from CELL5 to TP1, this represents the current, if the current is unusually high the part is broken.  If the current is 0 the part is not working.

    Check the cell inputs.  If an input broke you will have an open wire fault and both outputs will be low.  There are no test points but the unused capacitor pads are good probe points.

    Again if it is dead, replace it.