Pre-biased PNP for automotive and industrial loads
The ROHM DTB123YCHZGT116 is a PNP pre-biased digital transistor in a SOT-23-3 package, rated for 500 mA continuous collector current and 200 mW power dissipation. It integrates a 2.2 kΩ base resistor (R1) and a 10 kΩ emitter-base resistor (R2), which eliminates the need for two external bias resistors on the board. The part is qualified to AEC-Q101, making it suitable for automotive under-hood and chassis-domain applications, as well as industrial controls and power management circuits where temperature cycling and vibration are factors.
Built-in bias resistors — what they save on the BOM
With R1 at 2.2 kΩ and R2 at 10 kΩ, this transistor is self-biased for typical switching applications. The internal divider sets the base drive so that a logic-level signal from a microcontroller or sensor can switch the transistor on and off without additional passives. For a repair bench, that means one less component to check when a board comes in with a dead output driver — the scorch mark on the SOT-23 tells you the transistor went, not a missing resistor.
Switching performance and drive capability
The 200 MHz transition frequency supports switching into the low-MHz range, adequate for relay drivers, solenoid valves, indicator LEDs, and small DC motor pre-drivers. Vce saturation is 300 mV maximum at 2.5 mA base current and 50 mA collector current, so the voltage drop across the transistor stays low even when driving moderate loads. Minimum DC current gain of 56 at 50 mA, 5 V ensures consistent drive strength across production lots.
Package and footprint
Housed in a standard SOT-23-3 (SC-59, TO-236-3) surface-mount package with the SST3 supplier code. The footprint is shared across hundreds of small-signal transistors, so a board layout designed for a generic SOT-23 PNP will accept this part without modification.