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VNH5019 Thermal Issues above 20A

Question asked by Hans Dampf on Dec 2, 2017
Latest reply on Jan 12, 2018 by Electric Forest

Hi,

I've got some problems in getting the max Current capability of 30A out of the Chip. As soon as the Current goes above 20A the Chip will sooner or later switch of Halfbridge B. I think the problem is to get the Heat fast enough out of the Chip on to the PCB, because the PCB and the Heatsink have only a Temperature of 50°C. According to the datasheet the Die of the Chip should have a Temperature of 150°C-175°C in order to switch off one of the Half-Bridges. 

So it seems that the Heat accumulates inside the Chip.

Therefore my question is if the HeatSlugs of the VNH5019 are capable of transferring the power, which is lost under full load, out of the Chip at all. Has someone ever achieved 25A or 30A?

By the way it doesn't matter if the applied Voltage is 12V or 24V.

The PCB Power traces from and to the Chip have a thickness of 70um on the TOP and the BOTTOM site.

The Heatsink touches the Copper area and the Top of the Chip.

The ambient Temperature is around 20°C - 22°C

 

[EDIT] There is no PWM frequency. PWM leads HIGH level all the Time. So there should be no switching losses.

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