HF81

HF81 is an innovative two-terminal IC that automatically discharges an X capacitor while eliminating power losses and allowing power supplies to comply with safety standards. The HF81 acts as a smart high-voltage switch when placed in series with discharge resistors (alternatively bleed resistors). In the presence of an AC voltage, the HF81 blocks current flow in the safety discharge resistors to reduce the power loss in these components to zero at 230 VAC. When disconnected from the AC voltage, the HF81 automatically and safely discharges the X capacitor by closing the circuit through the bleed resistors and directing the energy away from the exposed AC plug. Table 1: Component Selection Table PN X Capacitance Total Series Resistance Power Saving(1) HF81 ≤500nF 1.5MΩ 750nF 1MΩ 66mW 1μF 780kΩ 86mW 1.5μF 480kΩ 142mW 2μF 360kΩ 191mW 2.5μF 300kΩ 230mW 3.5μF 200kΩ 347mW 5μF 150kΩ 464mW.