9.1 Application Information

The TPS23525 is a hot swap controller for –48-V applications and is used to manage inrush current and protect downstream circuitry and the upstream bus in case of fault conditions. The following key scenarios should be considered when designing a –48-V hot swap circuit:

• Start Up.
• Output of a hot swap is shorted to ground while the hot swap is on. This is often referred to as a Hot Short.
• Powering up a board when the output and ground are shorted. This is usually called a start-into-short.
• Input lightning surge. Here it is usually desired to avoid damage to downstream circuitry and to avoid system restarts.

These scenarios place a lot of stress on the hot swap MOSFET and the board designer should take special care to ensure that the MOSFET stays within it's Safe Operating Area (SOA) under all of these conditions. A detailed design example is provided below and the key equations are written out. Note that solving all of these equations by hand is cumbersome and can result in errors. Instead, TI recommends using the TPS2352X Design Calculator provided on the product page.