Depletion-mode small-signal switch for normally-on circuits
The Infineon BSS159NH6327XTSA2 is an N-channel depletion-mode MOSFET from the SIPMOS® family, packaged in a SOT-23-3 surface-mount case. Unlike enhancement-mode FETs, this device conducts current with zero gate voltage and requires a negative Vgs to pinch off — a characteristic useful for normally-on loads, current-source biasing, or fail-safe circuits where the load must stay powered if the gate drive is lost. Rated for 60 V drain-source and 230 mA continuous drain current at 25°C, it handles low-power switching and linear regulation in industrial, automotive, and telecom environments across a -55°C to 150°C junction temperature range.
On-resistance and gate drive — what the numbers mean for your circuit
Maximum on-resistance is 3.5 Ω at 160 mA drain current with 10 V applied to the gate. That Rds(on) is specified at a drive voltage of 10 V, but the part also supports a 0 V drive condition — the depletion-mode behaviour means the channel is fully on at zero gate bias. Gate charge is only 1.4 nC at 5 V, so the gate driver sees a light capacitive load; switching losses stay low even with a simple logic-level drive. Input capacitance is 39 pF at 25 V Vds, confirming this is a small-signal part suited for frequencies into the low-MHz range without excessive drive current.
Package and mounting
The SOT-23-3 (PG-SOT23) footprint is standard for low-power discretes. Power dissipation is limited to 360 mW at ambient temperature — adequate for signal-level switching but not for continuous high-current loads. The surface-mount package suits automated assembly and reflow processes common in high-volume production.
Lifecycle and sourcing
The BSS159NH6327XTSA2 carries an Active product status with ROHS3 compliance. No end-of-life notice or last-time-buy window is indicated.