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How to avoid soft-start retries during persistent short to ground?

How to avoid soft-start retries during persistent short to ground?

Infineon_Team
Employee
Employee
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Boost topologies have a direct path from battery to the output. If a short to ground happens at output, the current on this path is not controlled anymore and could damage the DC-DC.

In case of output short to ground TLD6098-1EP and TLD6098-2ES protect the DC-DC by using the a PMOS connected to PWMO gate driver. During the short, the device continuously retries a soft-start routine to sense if the fault has been removed.

In this operation mode the PMOS could rise its junction temperature above the maximum absolute rating.

To avoid the PMOS damage due to high temperature operation, the DC/PWMI pin can be lowered to stop the retry. To do that, a network with Diode D2  and current limiting resistor RLIM can be used as shown in the figure below. This solution allows to sense a short on VOUT and providing a proper bias to PWMI pin in all the cases.

Image1.png

Figure 1: Network with D2 & RLIM

 

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