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LMG5200: I could not use the LMG 5200.

user5326656
Prodigy 30 points
Part Number: LMG5200

I could not use the LMG 5200.

I think that I will write the reason first.

Only voltage of 2 V to 3 V can be applied between VCC pin and AGND.
Current flows from 1A to about 2A, between the pins.
That's why I believe it is short-circuited. But I do not know why such a thing happened.

So I will describe everything that I did.

I applied cream solder to each metal part of the backside terminal.
And the metal feet were attached to the metal parts of each terminal.
It is now possible to enter signals.

A 0.1 μF laminated ceramic capacitor was soldered between the VCC pin and the AGND pin and between the HS pin and the HB pin.

I input a 3 V pulse signal to the HI and LI pins using the FPGA.
A pulse signal with a period of 50 us was input to the HI pin.
Next, the pulse signal input to the HI pin is inverted, and a 48 μs pulse signal with 1 us set as the dead time is input to the LI pin.

5 V was applied from the voltage source between VCC pin and AGND pin.
Next, 15 V was applied from the voltage source between the VIN pin and the PGND pin.

And 5 V could not be applied between VCC pin and AGND pin.
As I wrote in the beginning, the voltage can only be applied from 2 V to 3 V, and the current will increase from 1A to about 2A.
This is turning the current pin, no voltage can be applied, only the current is applied.

Since I use half-bridge GaN like CMOS, I wanted to try first if LMG 5200 could be used.
However, it was impossible to apply a voltage between the VCC pin and the AGND pin in the first place, and the LMG 5200 could not operate.

I am very thankful if you will help me.

  • 0
    TI__Expert 3225 points
    Hello,

    Since you mentioned that 5V was applied and then 15V was applied, have you ever successfully supplied the voltage at 5V when there is no VIN? It looks to me the driver is damaged to lead to such a high supply current. The 5V supply current for LMG5200 in typically in mA range.

    Also, how many LMG5200 have you checked? To have the device working, another bootstrap cap between HB and HS is also needed. Please also recheck your design and look into our EVM design as a reference for a good layout.
    www.ti.com/.../lmg5200evm-02

    Thanks and regards,
    Lixing
  • 0
    TI__Intellectual 805 points

    Hello,

    As Lixing mentioned, the part is already damaged. I couldn't quite clearly understand how you soldered the device terminals but it sounds to me that you are not using a pcb but just solder some wire to the bottom side terminals. One problem you may be facing is that VCC exceeds 6V even though you mentioned that you applied 5V. To avoid overshoots, the bypass capacitor should be placed very close to VCC pin. I'm thinking that this may be the problem. Otherwise, LMG5200 should operate just fine for what you are trying to do. Please check the EVM and critical design rules.

    Regards,

    Serkan

  • 0 in reply to Lixing Fu
    Prodigy 30 points

    Mr. Lixing, thanks for Reply.
    I was deeply impressed by the prompt response.

    My writing style was bad. It is my mistake that did not convey correctly.

    I was going to apply 5V first and then apply 15V.
    The order of input I was thinking is (1) HI and LI pins, (2) 5 V, (3) 15 V.

    So I input signals to the HI and LI pins and then I tried to add 5V.

    Actually, 5 V can not be applied, a voltage of about 2 V is applied and the current can be drawn to 2A, 3A.
    Therefore, when there is no VIN (15 V), 5 V can not be applied.

    As you wrote, if flowing current is in mA, I think the LMG 5200 I used is certainly broken.

    According to the datasheet, I attached a 0.1 μF laminated ceramic capacitor between the VCC pin and AGND.
    A 0.1 μF multilayer ceramic capacitor was attached as a bootstrap capacitor between HS and HB.

    I made the two LMG 5200 in the same state before applying voltage to LMG 5200 this time.
    So, I thought about soldering temperature as a cause of breakage, but this time I think that it was not broken by temperature because it was soldered using cream solder.

    Thank you for telling me the URL, I will check it.

  • 0 in reply to Serkan Dusmez
    Prodigy 30 points
    Sercan, Thank you for doing the Reply.
    I was deeply impressed by the prompt response.

    I did not use the PCB, I thought first to see if the LMG 5200 works properly. And I was planning to understand how to use it.

    Solder the metal feet to each of the nine terminals on the bottom side and set the bypass capacitor at a very close point.
    A multilayer ceramic capacitor of 0.1 μF was used as a bypass capacitor.

    I thought about applying 5 V when written exactly, but it was a mistake that I could not apply it.
    I think that my writing was bad.

    As the order of applying voltage, I was thinking of (1) HI pin and LI pin, (2) 5 V between VCC pin and AGND pin, and (3) 15 V between VIN pin and PGND pin.
    However, 5 V could not be applied first.

    The applied voltage was about 2 V and the current could only flow to 1A 2A.

    As Lixing and Sercan wrote, I think that parts are broken.

    But I do not know the cause.
    Prior to using LMG 5200 this time, the same phenomenon occurred in the two LMG 5200.
    At that time, I thought that the soldering temperature was the cause.
    So this time I tried using cream solder to reduce damage caused by temperature to the back terminals.

    I will review EVM and important design rules.