The STMicroelectronics L7912ACV is a negative fixed linear regulator delivering a regulated -12V output at up to 1.5A. It is the go-to part when you need a clean, low-noise negative rail from a more negative input (up to -35V maximum) for op-amp supplies, analog front-ends, or bipolar power architectures. The fixed output means no external resistor divider — just the input cap and output cap per the datasheet recommendation, and it regulates. Its 60dB power-supply rejection ratio at 120Hz is the figure that matters if this rail feeds an audio preamp, a precision ADC reference buffer, or any circuit where line-frequency ripple couples into the signal path. 60dB at the fundamental line frequency is a solid, workmanlike number for a three-terminal regulator — it knocks a 1Vpp ripple down to 1mVpp at the output, which keeps most analog stages happy without a post-filter. The 1.5A rating is the maximum output current before thermal protection engages. With the TO-220 package heatsunk, 1A continuous is sustainable.
Through-hole TO-220 — thermal and assembly reality
For the L7912ACV, the tab is at -12V potential, so the heatsink must be electrically isolated or the system ground must be floated — a common gotcha when replacing a positive regulator. The package is rated for the full 1.5A output only when the tab is properly heatsunk; in free air at 25°C, derate to about 0.5A before the thermal shutdown cycles. The mounting type is through-hole, so the board needs drilled holes and wave-solder or hand-solder assembly. No reflow profile to worry about, but the tab must be soldered or bolted to a heatsink for any load above a few hundred milliamps.