40 V, 120 mA AEC-Q101 Schottky — what this diode is for
The Infineon BAS40B5000 is a small-signal Schottky diode rated for 40 V DC reverse voltage and 120 mA average rectified current, housed in a PG-SOT23 surface-mount package. It carries AEC-Q101 automotive qualification, making it suitable for use in automotive electronic control units, sensor interfaces, and other systems requiring a certified device for under-hood or chassis-domain deployment. The Schottky construction gives a low forward voltage of 1 V at 40 mA and a fast switching characteristic — classified as Small Signal =< 200 mA, Any Speed.
The 40 V reverse voltage rating provides adequate headroom for 12 V and 24 V automotive rails, though it is not intended for 48 V systems. At 120 mA average forward current this is a signal-level diode, not a power rectifier — it handles clamping, flyback catch, and low-current OR-ing, not bulk supply rectification. Reverse leakage is specified at 1 µA at 30 V, which is typical for a Schottky of this voltage class and acceptable for most low-power analog and digital inputs. Junction temperature is rated to 150 °C, matching the under-hood thermal requirement for AEC-Q101 devices. The 3 pF capacitance at 0 V, 1 MHz is low enough for high-frequency signal clamping up into the low-GHz range, though the SOT-23 package parasitics will dominate above a few hundred MHz. For RF detector or mixer applications, a smaller SOD-323 or SOD-523 Schottky would be a better fit; this part is optimised for general-purpose automotive and industrial signal conditioning.
AEC-Q101 and lifecycle — no obsolescence concern
It is an automotive-qualified series, which typically means longer production commitments and a well-managed PCN process compared to commercial-grade parts. For new designs, this part presents no lifecycle risk through the typical automotive program lifetime.
SOT-23 footprint and mounting
It is a surface-mount device with three leads — anode, cathode, and no separate substrate connection. The footprint is common across the BAS40 family and compatible with standard SOT-23 land patterns.