LMG34XX-BB-EVM: R9 burns out

sanghwa Lee

Part Number: LMG34XX-BB-EVM
Other Parts Discussed in Thread: LMG3410-HB-EVM

I buy LMG3410 HB EVM and LMG34XX-BB-EVM board, and use them together

I am using 3 phase power supply to supply DC power through 3 phase diode rectifier.

The PWM signal uses a BNC connector and supplies a 12V supply to the LMG34XX BB EVM board.
However, when the power is turned on, the R9 resistance of the LMG34XX BB EVM board burns out.
And when the power is turned on in that state, the 12V power supply current is severely affected by noise above a certain voltage.
I want to solve this problem. Help.

over 6 years ago

0 Serkan Dusmez over 6 years ago

TI__Intellectual 805 points

Hello Sanghwa,
I'm sorry to hear that you are experiencing problems with the LMG3410 HB and BB boards. We never encountered this problem so I suspect there is something wrong with the power supplies. The R9 resistor is placed to increase the inductance between AGnd and PGnd so that high dv/dt current does not interfere the AGnd. Burning that resistor would mean that large DC current is going through that net. Have you placed a hold up capacitor after your three-phase rectifier? Also, is 12V supply isolated from the DC input?
Regards,
Serkan

0 sanghwa Lee over 6 years ago in reply to Serkan Dusmez

Prodigy 65 points

We have a capacitor after the three-phase rectifier and use an isolated 12V DC.

0 Serkan Dusmez over 6 years ago in reply to sanghwa Lee

TI__Intellectual 805 points

Hello Sanghwa,
Can you just make sure nothing overheats when you just supply 12V with no input connection?
If you don't see over-current (draws about 60-70 mA at 100kHz frequency), can you supply DC voltage from an isolated DC supply rather than directly rectifiying AC voltage? I still think the problem is external to the board.
Regards,
Serkan

0 Serkan Dusmez over 6 years ago in reply to Serkan Dusmez

TI__Intellectual 805 points

Also, the circuit should work without soldering R9 as the gate and FAULT signals are isolated for low side FET on the LMG3410-HB EVM. You can try to run it w/o soldering R9.

0 sanghwa Lee over 6 years ago in reply to Serkan Dusmez

Prodigy 65 points

We can not use it without a diode rectifier.

We plan to buy LMG3410-HB-EVM and use it directly.

However, there was a problem with the design because the supply capacity of "LMG3410-HB-EVM" could not be determined (there is no HB-EVM board supply capacity in the data sheet).

Could you tell me how many power "LMG3410 HB EVM" needs?
I want to know the power at 130kHz.(HVIN DC input voltage 350V, output current 3.5A)

0 Serkan Dusmez over 6 years ago in reply to sanghwa Lee

TI__Intellectual 805 points

I will check it tomorrow and get back to you.

0 Serkan Dusmez over 6 years ago in reply to Serkan Dusmez

TI__Intellectual 805 points

Hello Sanghwa,
The boards all together consume 70mA at 100kHz and 75mA at 130kHz from a 12V supply. For LMG3410, you can check the supply current vs fsw from the datasheet.
www.ti.com/.../lmg3410.pdf

Regards,
Serkan

0 sanghwa Lee over 6 years ago in reply to Serkan Dusmez

Prodigy 65 points

Is there any difference in power even when the input voltage of HVIN input DC voltage increases?

Is the 12V current of the only HV-EVM board 75mA? (without including LMG34XX BB EVM board)

0 Serkan Dusmez over 6 years ago in reply to sanghwa Lee

TI__Intellectual 805 points

LMG3410 draws about 4.5mA at VDS=0V and 5.5mA at VDS=400V at 100kHz.

0 sanghwa Lee over 6 years ago in reply to Serkan Dusmez

Prodigy 65 points

Thank you for your kindly reply.
Previously, you said 75mA at 12V supply. (130 kHz)
Is the 75mA only for the LMG3410 HB EVM without the LMG34XX-BB-EVM?

If not, can you tell me only the LMG3410 HB EVM power?

If possible, HVIN = 350V, output current = 3.5A.

thansk you

0 Serkan Dusmez over 6 years ago in reply to sanghwa Lee

TI__Intellectual 805 points

Hello Sanghwa,

The LMG3410 HB board and LMG34XX-BB-EVM together draws 75mA at 130kHz from a 12V supply. However some of the power is lost on the LDO of LMG34XX-BB-EVM board. To find out how much current each board draws, I separated the two supplies; 1) supplied 12V to the BB board; 2) supplied 5V to the HB board.In this case;

LMG3410-HB board draws about 70mA from a 5V supply at 130kHz Vds=350V, and IL=3.5A (current does not impact the driver current consumption)
LMG34XX-BB-EVM board draws about 10mA at 12V supply.

This effectively means that if you supply 12V to the BB board, LMG3410-HB burns about 0.35W, and rest of power (12V*0.075 - 0.35W=0.55W) is lost on the LMG34XX-BB-EVM and on its LDO.

Hope this helps.

Let us know if you have any further question.

Regards,

Serkan

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LMG34XX-BB-EVM: R9 burns out