The ROHM UML23NTR is a surface-mount NPN transistor with an integrated Zener diode on the same die, isolated from the collector. This is not a plain NPN — the Zener is there for a reason, typically clamping the base-emitter junction or providing a stable reference in a bias network. For a BOM line, that means one fewer discrete diode to place and qualify, assuming the circuit can use the internal clamp. The transistor side is rated for a 50V collector-emitter breakdown, 150mA collector current continuous, and a minimum DC current gain of 120 at 1mA / 6V. The 180MHz transition frequency puts it in the general-purpose amplifier and moderate-speed switching class, not a high-current driver or RF power stage.
Switching envelope and saturation voltage
The Vce(sat) is specified at 400mV maximum with a 5mA base drive into a 50mA collector load. That is a forced beta of 10, which is the usual saturation condition for a switching transistor. If you are driving a relay coil, a small solenoid, or an LED string at 50mA, this part will saturate cleanly with a 5mA GPIO drive. The 100nA collector cutoff current is tight enough for battery-powered circuits where leakage matters at elevated temperature — though the 150°C junction rating means the leakage will climb, so budget for it above 85°C.
Package and storage on the reel
The UML23NTR comes in a UMT6 package, which is the ROHM name for a 6-pin SOT-363 / SC-88 footprint. It is a small surface-mount package — about 2.0mm x 2.1mm — so board space is minimal. The suffix 'TR' means it ships on a Tape & Reel, and it is also available in Cut Tape for prototype quantities. Store the reels dry: the MSL rating is not listed in the spec summary, but SOT-363 is typically MSL 1, so no bake required unless the bag has been open for an extended time.
Lifecycle — no LTB worry here
If you are stocking for a five-year production run, this is not a part that needs a panic buy.