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LMG5200: Using BOOSTXL-3PHGANINV in dual active bridge

Patrick Ford
Prodigy 30 points
Part Number: LMG5200
Other Parts Discussed in Thread: BOOSTXL-3PHGANINV,

Tool/software:

I am using two of the BOOSTXL-3PHGANINV boards along with an F28379D to make a dual active bridge. This works fine when using a common VBUS supply between the two BOOSTXL boards and just controlling the power flow in forward or reverse.

However, in order to run unidirectional with external load I cannot apply external power to VBUS on the secondary side board.

I removed the inductors L1/L2 on the board to bypass the 48-5V converter and applied 5V externally. All power LEDs are lit up and I confirmed that PWM signals are reaching the LMG5200 chip correctly. However, when running the output voltage is equal to supply minus a diode drop (e.g. 10V in, 8.6V out) implying that the LMG5200 is not actually switching.

Is there something internal to the LMG5200 that prevents the IC from switching when there is no external VBUS applied?

  • 0
    TI__Expert 3415 points

    Hi Patrick, 

    To confirm, are you prototyping a three-phase dual active bridge with two of the BOOSTXL-3PHGANINV? Can you please share a schematic of this configuration? 

    In addition, please check the voltage from VCC to GND and HB to HS on each LMG5200 device and ensure they are within the recommended conditions in the datasheet. 

    The LMG5200 should not have any issue switching without an external voltage applied to VIN pin. 

    Thanks,

    John