Dual pre-biased NPN in a small SOT-363 package
The Infineon BCR 133S H6444 integrates two NPN transistors with built-in bias resistors in a single SOT-363 package. Each transistor includes a 10kΩ base resistor (R1) and a 10kΩ emitter-base resistor (R2), eliminating the need for external biasing components in low-current digital switching applications like relay drivers, LED drivers, and logic-level interfaces.
Key ratings for circuit design
The collector-emitter breakdown voltage is rated at 50V, and the maximum continuous collector current is 100mA, making this part suitable for 24V industrial logic and small-signal loads. The DC current gain (hFE) is a minimum of 30 at 5mA collector current and 5V VCE, which is typical for a pre-biased transistor in saturation-mode switching. The transition frequency of 130MHz is adequate for low-speed switching below a few megahertz. Maximum power dissipation is 250mW for the dual package, so derating is needed when both transistors conduct simultaneously.
Obsolete — sourcing for sustainment
The BCR 133S H6444 is listed as obsolete by Infineon. Engineers should verify pin-compatible alternatives within the BCR 133 family or consider a discrete resistor-plus-transistor solution if a drop-in replacement is not found.