LM7912 -12V Negative Linear Regulator Regulated Load Supply

Application

This circuit uses LM7912 -12V Negative Linear Regulator as a fixed negative rail regulator feeding a simple resistive load. It is a practical starting point for checking input headroom, output voltage, and load current in a small regulated supply.

Design Context

VIN is set to -18 V and feeds the regulator input. The regulator common pin is tied to ground, and RLOAD connects the regulated -12 V output to the same return. Vin, Vout, and Iload probes make the steady-state operating point visible in the table.

Expected Behavior

Vout should settle near -12 V while the input remains at the unregulated supply value. The load current flows from ground through RLOAD into the negative output rail, so the current sign depends on probe direction.

Key Values

• VIN: -18 V input supply.
• RLOAD: 2.4K load resistor.
• Expected output rail: -12 V.
• Simulation: DC operating point for steady-state supply behavior.

Suggested Experiments

• Increase or decrease RLOAD to compare output current and regulation margin.
• Move VIN closer to the output voltage to explore dropout behavior.
• Add input or output capacitors when comparing this idealized starter circuit to a datasheet application circuit.

Featured Component

LM7912 -12V Negative Linear Regulator is the fixed-output linear regulator in this supply. The demo highlights its input, common, and regulated-output terminals in the standard three-terminal application topology.