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LTC7000 damaged with 6.8mF output capacitor

Question asked by TanNianYou on Jun 14, 2018
Latest reply on Jun 27, 2018 by Gene323

Hi I am using LTC7000 as high side switch with Dual NFETs. The schematic is attached here. 

 

The part number for M1 and M2 are IPB015N08N5ATMA1 but not the components shown in the schematic.

The I1 load is actually an electronic load.

In this test, I start the test with Iload gradually increase from 1A to 9A. When C4 (6.8mF) is not included, the LTC7000 is working properly and the dual MOSFETs are turned on properly. The Vgs of dual NFETs are 12V.

When C4 is included, the LTC7000 is working properly until the Iload reaches 7A. When Iload is 7A, it is found out the TGup pin and Vcc pin is 0V. Besides this, Vcc pin is shorted to Ground pin as well. This happens at the instance I turn On the power supply. I believe the LTC7000 has been damaged.

I have added in C8 and R4 to have a soft-start on dual NFETs as we have a large capacitor (6.8mF) on output side. Would you have any idea what might cause the damage on IC? Is there any way I can prevent this?  

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