Active production — -12V fixed output at 1.5A
The LM7912CT/NOPB is an active-production negative fixed linear regulator from Texas Instruments, delivering a regulated -12V output at up to 1.5A continuous. This is the through-hole TO-220-3 variant, shipped in tube packaging. The -12V rail is a common requirement for bipolar analog supplies — op-amp circuits, audio preamps, and industrial sensor interfaces that need a symmetrical ±12V pair. The 1.5A rating covers moderate loads like multiple op-amp stages or a small relay bank.
The 70 dB PSRR at 120 Hz means the output rejects 99.97% of the 100/120 Hz ripple from a full-wave rectifier. For an audio preamp or a precision ADC reference, that ripple attenuation keeps the power-supply hum out of the signal band. At higher frequencies the PSRR rolls off, so the upstream bulk capacitance and a low-ESR electrolytic at the regulator input are what keep switching noise from coupling through. The 1.5 mA quiescent current is modest for a 1.5 A part — the regulator's own draw is negligible compared to the load.
Dropout and protection — 1.1 V headroom at 1 A, thermal and short-circuit safe
Maximum dropout is 1.1 V at 1 A load, meaning the input must stay at least 1.1 V below the -12 V output (i.e., more negative than -13.1 V) to maintain regulation. A -15 V to -18 V unregulated rail is the typical feed — the extra headroom covers line ripple and temperature drift. Built-in over-temperature and short-circuit protection let the regulator survive a sustained output short or a thermal overload without external crowbar circuitry. The TO-220-3 tab is the thermal path — a heatsink is needed above a few hundred mA in still air.
Compliance and sourcing
No pin-compatible second source is documented — the LM7912 footprint is unique to the 79xx series negative regulators.