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. The ROHS3 compliance is confirmed, which covers the full substance restriction including phthalates.
Lifecycle — no LTB worry here
There is no NRND flag, no last-time-buy notice, and no successor part listed. If you are stocking for a five-year production run, this is not a part that needs a panic buy.