STMicroelectronics L7815CP

Overview

L7815CP from STMicroelectronics is a three-terminal positive fixed-voltage linear regulator delivering 15 V ±3% output at up to 1.5 A, featuring thermal overload protection, short-circuit current limiting, and safe operating area (SOA) protection. It operates with input voltages up to 35 V (for VO = 15 V), maintains 2 V dropout at 1 A, and supports industrial temperature range (0 to 125 °C) in TO-220 package - widely used for local regulation in power supplies for microcontroller-based control systems, instrumentation, and industrial sensors.

For engineers reviewing the L7815CP datasheet, L7815CP pinout, L7815CP application, or L7815CP equivalent, key selection criteria include guaranteed 15 V output tolerance, thermal shutdown behavior under sustained load, dropout voltage margin at full current, and compatibility with standard 0.33 µF input / 0.1 µF output capacitor network per ST's test circuits.

Technical Context

The L7815CP implements a monolithic bipolar linear regulator architecture with internal PNP pass transistor, error amplifier, bandgap reference, and protection circuitry. Its feedback loop stabilizes output against line (input) and load (output current) variations, while built-in thermal sensing triggers shutdown above ~165 °C junction temperature.

It requires no external components for basic operation but relies on specified input/output capacitors (CI = 0.33 µF, CO = 0.1 µF) to ensure stability and ripple rejection - particularly critical given its 58 dB supply voltage rejection at 120 Hz and 19 mΩ output resistance.

Key Specifications

Pinout & Package

Package: TO-220 (3-pin, vertical mounting, metal tab connected to ground). Requires mechanical mounting to heatsink via tab for >500 mA operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output linear regulator applications.

Compared with LM7815CT, L7815CP offers superior ripple rejection and tighter output tolerance; versus MC7815CD2TR4G, it trades slightly higher dropout and thermal resistance for broader industrial temperature qualification and proven field reliability in harsh environments.

Availability

L7815CP is available at Aetrix Electronics and suitable for industrial automation, test equipment, and automotive body electronics requiring stable component supply, long-lifecycle support, and consistent parametric performance across production batches.

Supply support for L7815CP includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing silicon solutions for automotive, industrial, and power management applications.

The L78 series belongs to ST's mature positive voltage regulator IC product line, engineered specifically for robust, low-cost, drop-in local regulation in industrial control, instrumentation, and legacy system upgrades where simplicity and reliability outweigh switching efficiency demands.

FAQ

What is the minimum input voltage required for stable 15 V output at 1 A?

The L7815CP requires a minimum input voltage of 17 V to maintain regulation at 1 A load, based on its 2 V dropout specification at 25 °C. At elevated temperatures or higher currents, derating is advised - ST recommends VI ≥ 18 V for full 1.5 A capability with margin. Input below 17 V causes output to track input minus dropout, resulting in unregulated behavior.

Does L7815CP require external capacitors, and what values are recommended?

Yes - ST specifies a 0.33 µF ceramic capacitor on the input (within 10 cm of Pin 1) and a 0.1 µF ceramic capacitor on the output (within 1 cm of Pin 3) for stability and transient response. These values are validated in DS0422 Rev 38 test circuits. Omitting either capacitor risks oscillation or poor load-step recovery, especially with long PCB traces or inductive sources.

How does thermal performance differ between TO-220 and TO-220FP packages for L7815CP?

The TO-220FP variant has R_thJA = 60 °C/W versus 50 °C/W for standard TO-220, meaning it runs ~10 °C hotter at same power dissipation without heatsinking. However, TO-220FP's insulated case allows direct mounting to grounded heatsinks without isolation hardware. For L7815CP delivering 1 A at 15 V with 10 V input differential (10 W dissipation), both require ≥10 °C/W heatsinks to stay below 125 °C junction temperature.

Can L7815CP be used in adjustable configuration, and what is the limitation?

Yes - by adding two external resistors to the ground pin (per ST application note AN235), L7815CP can generate adjustable outputs above 15 V. However, the internal reference remains fixed at ~15 V, so minimum output is clamped at 15 V. Also, output current capability decreases as V_OUT increases due to higher power dissipation in the pass element and reduced headroom for thermal management.