4 A peak drive with 200 kV/µs CMTI — gate-driver isolation for hard-switched power stages
The Skyworks SI8275BBD-IS1 is a 2-channel RF-coupled digital isolator in the Si827x family, purpose-built for driving power semiconductors across an isolation barrier. Its 4 A peak output current drives the gate capacitance of medium-power IGBTs and SiC FETs directly, while the 200 kV/µs minimum common-mode transient immunity keeps the output state valid when the switching node slews at tens of kV/µs — a half-bridge shoot-through risk if the isolator's output glitches during a hard commutation. Rated for 2500 Vrms isolation and carrying CQC, CSA, UL, and VDE approvals, the part is accepted for reinforced-insulation designs in motor drives, solar inverters, and industrial power supplies that must meet IEC 60950-1 or IEC 61800-5-1 clearance and creepage requirements.
75 ns propagation delay — dead-time budget and timing margin
Maximum propagation delay is 75 ns for both rising and falling edges, with a pulse-width distortion ceiling of 8 ns. In a 100 kHz switching stage with 500 ns dead time, the 75 ns delay consumes 15 % of the dead-time budget — the remaining margin must cover driver mismatch and temperature drift. The 10.5 ns typical rise and 13.3 ns fall times into a 1 nF gate load mean the actual voltage at the IGBT gate lags the isolator output by roughly one switching cycle at 1 MHz. The 4.2 V to 30 V output supply range covers standard IGBT gate voltages (+15 V) and SiC gate drives (+18 V to +20 V), while the 1.8 A source / 4 A sink asymmetry reflects the typical requirement: a strong pull-down to clamp the gate off during Miller plateau events, with a softer pull-up to limit di/dt during turn-on.