4 Safety and Insulation

Isolating the control and indication signals (management signals) from the high-voltage section and enabling the system to communicate with the hot-swap controller is important. The insulation for these signals must comply with reinforced insulation for Pollution Degree 2, 10% to 90% humidity noncondensing (per safety standard International Electrotechnical Commission [IEC] 62368-1) and clearance and creepage distances for up to 3,050m of altitude (5,000m preferably).

The LMI800PS device package—with ≥8mm of creepage between the high- and low-voltage domain, a 5kVrms isolation withstand voltage (V_ISO) rating and 10kV of surge capability—meets the overall safety requirements.

One of those safety requirements is to discharge the output bulk capacitors to <120V within 2s when the IT tray disconnects from the rack, or when the output disconnects. Placing a FET with series discharge resistors in parallel to the output capacitors can enable this feature. The LMI800PS features a discharge FET control output signal, simplifying output discharge design.