1200 V N-channel — high-voltage primary switch for 800 V bus designs
The STH13N120K5-2AG: It is built on the K5 planar technology family and comes in the H2PAK-2 surface-mount package — a TO-263-derivative with two leads plus a tab for the drain connection. The 1200 V rating places it in the class of parts used for 800 V DC bus rails, 3-phase 380 VAC rectified supplies, and high-voltage auxiliary converters in industrial and renewable-energy equipment.
Conduction loss at 6 A — 690 mOhm on-resistance sets the thermal budget
Rds(on) is specified at 690 mOhm maximum with 6 A drain current and 10 V gate drive. The 250 W power dissipation rating at the case (Tc) gives headroom for pulsed operation, but continuous 12 A at high duty cycles will push the junction toward the 150 °C absolute maximum, so the PCB copper area under the tab is the limiting factor.
Total gate charge Qg is 44.2 nC at 10 V Vgs. The ±30 V maximum gate-source rating gives room for overshoot on the gate node, but the 5 V threshold maximum at 100 µA means the logic-level drive at 5 V may not fully enhance the channel — the 10 V drive voltage is the recommended operating point for minimum Rds(on).
Input capacitance — 1370 pF at 100 V drain bias
The input capacitance Ciss is 1370 pF typical at 100 V Vds. This is a moderate figure for a 1200 V device; it keeps the switching-node ringing manageable and does not require an oversized gate-drive resistor to slow the turn-on edge. The 100 V test bias is a standard datasheet condition — the capacitance drops as the drain voltage rises toward the 1200 V rating, which actually improves the switching performance at the nominal bus voltage.