Two NPN transistors with built-in bias resistors
The Rohm Semiconductor UMH2NTN packs two NPN pre-biased transistors into a single SOT-363 package, each with 47 kΩ resistors in both the base and emitter-base legs. That means each transistor channel arrives with its bias network already on-die — no external R1 or R2 needed, which cuts two resistors per channel from the BOM and shrinks the layout to a 2.0 mm × 2.1 mm footprint. The 250 MHz transition frequency keeps switching clean into the low-MHz range, adequate for PWM fan control or serial bus translation up to a few megahertz.
Saturation voltage and gain at low current
VCE(sat) is specified at 300 mV maximum with 500 µA base drive and 10 mA collector current — a typical operating point for driving an optocoupler LED or a small relay coil. The DC current gain minimum of 68 at 5 mA, 5 V means the part stays in saturation with modest base current, which matters when the drive comes from a GPIO pin with limited source capability. Off-state leakage is 500 nA maximum, low enough to avoid false triggering in high-impedance loads.