STMicroelectronics L7915CD2T

Overview

L7915CD2T from STMicroelectronics is a fixed-output, three-terminal negative linear voltage regulator delivering -15 V at up to 1.5 A, featuring thermal overload protection, short-circuit protection, and output transition SOA protection. It operates with input voltages down to -35 V (for VO = -15 V), supports local on-card regulation in split-supply systems, and is commonly used in ±15 V analog power rails for op-amp circuits and industrial control interfaces.

For engineers reviewing the L7915CD2T datasheet, L7915CD2T pinout, L7915CD2T application, or L7915CD2T equivalent, key selection criteria include guaranteed -15 V output tolerance (±3.3% at 25°C), dropout voltage of 1.1 V at 1 A, junction temperature range of 0–150°C, and D²PAK package thermal resistance (R_thJC = 3°C/W) for high-power dissipation scenarios.

Technical Context

The L7915CD2T implements a monolithic PNP pass transistor architecture with internal current limiting, thermal shutdown, and safe operating area (SOA) protection during transient overloads. Its feedback loop maintains output regulation across line (VI = -18.5 V to -30 V) and load (IO = -5 mA to -1.5 A) variations while minimizing drift (ΔVO/ΔT = -0.9 mV/°C).

Designed as a complementary device to the L78xx positive regulator series, it enables symmetrical dual-rail supplies without external compensation. Stability requires ≥2.2 µF solid tantalum input capacitor and ≥1 µF output capacitor; aluminum electrolytics require ≥10× capacitance value per ST's application note guidance.

Key Specifications

Pinout & Package

Package: D²PAK (TO-263), surface-mount, thermally enhanced with exposed drain pad for PCB heat sinking. R_thJC = 3°C/W enables >1.5 A operation with adequate copper area.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar negative fixed-voltage regulator applications.

Compared with LM337T and MC7915BT, the L7915CD2T offers superior thermal efficiency in SMT layouts, eliminates resistor-based trimming overhead, and delivers tighter initial output tolerance (±3.3% vs. ±4% for MC7915BT), making it optimal for production-ready ±15 V analog subsystems.

Availability

L7915CD2T is available at Aetrix Electronics and suitable for industrial instrumentation, audio power amplifiers, programmable logic controllers, and analog signal conditioning requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for L7915CD2T 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 microcontrollers, power management ICs, analog chips, and MEMS sensors for industrial, automotive, and consumer markets.

The L79xxC series belongs to ST's legacy linear regulator product line, engineered specifically for robust, low-cost, fixed-output negative voltage regulation in dual-rail analog and industrial control systems where reliability and thermal resilience are prioritized over ultra-low quiescent current.

FAQ

What is the maximum input voltage for L7915CD2T?

The absolute maximum DC input voltage is -35 V when regulating -15 V output, as specified in Table 2 of the datasheet. Operation above this rating risks permanent damage. For reliable long-term use, ST recommends limiting VI to ≤ -30 V under worst-case conditions including ripple and transients.

Can L7915CD2T be used in adjustable configurations?

Yes - though designed as a fixed -15 V regulator, the L7915CD2T can be configured as an adjustable negative regulator using external resistors per Figure 6 in the datasheet. The output voltage becomes VO = V_XX(R1 + R2)/R2, where V_XX is the base regulator's nominal output (-15 V), enabling custom negative voltages with appropriate stability compensation.

Is a heat sink required for 1.5 A operation?

Yes - at 1.5 A with a 10 V input-to-output differential, power dissipation exceeds 15 W. With R_thJC = 3°C/W and typical PCB copper area, junction temperature will exceed 150°C without supplemental heatsinking. ST recommends a low-thermal-resistance heatsink attached to the exposed D²PAK pad, or forced-air cooling for continuous full-load operation.

What capacitor types are mandatory for stability?

A minimum 2.2 µF solid tantalum capacitor is required at the input, and 1 µF solid tantalum at the output. Aluminum electrolytic capacitors may be substituted only if capacitance is increased ≥10× (i.e., ≥22 µF input, ≥10 µF output), due to higher ESR affecting phase margin. Ceramic capacitors alone are insufficient and may cause oscillation.