STMicroelectronics L7908CV-DG

Overview

L7908CV-DG from STMicroelectronics is a fixed-output, three-terminal negative linear voltage regulator delivering -8 V at up to 1.5 A output current. It features thermal overload protection, short-circuit protection, and SOA-limited output transition capability. Designed for local on-card regulation in split-supply systems, it replaces legacy L79xxC variants with enhanced dual-gauge TO-220 packaging for improved mechanical robustness and thermal reliability.

For engineers reviewing the L7908CV-DG datasheet, L7908CV-DG pinout, L7908CV-DG application, or L7908CV-DG equivalent, key selection criteria include guaranteed -8 V output tolerance (±5%), dropout voltage of 1.1 V at 1 A, thermal resistance of 5 °C/W (junction-to-case), and compatibility with standard ±15 V split-rail power architectures in industrial control and analog signal conditioning circuits.

Technical Context

This device operates as a monolithic PNP-based series pass regulator with internal current limiting, thermal shutdown, and safe operating area (SOA) protection. Its feedback loop maintains output regulation across input voltages from -11.5 V to -23 V and load currents from -5 mA to -1.5 A, with line regulation of 80 mV over a narrow input range and 160 mV over full range.

The L7908CV-DG uses a fixed internal resistor divider to set nominal -8 V output, eliminating external components for basic operation. It supports adjustable configurations via external resistors but requires external capacitors (2.2 µF input, 1 µF output) for stability-solid tantalum recommended per ST's design guidance.

Key Specifications

Pinout & Package

Package: TO-220FP (ST Dual Gauge frame, 3-pin vertical mounting, ECOPACK® compliant). Pin assignment verified per Figure 2 (top view) in ST Doc ID 2149 Rev 21.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM337T and L7908CD2T-TR, the L7908CV-DG offers optimal balance of mechanical robustness (dual-gauge TO-220FP), thermal performance (5 °C/W R_thJC), and plug-and-play simplicity for fixed -8 V applications-making it preferred for industrial repair, legacy board refresh, and mixed-technology assemblies.

Availability

L7908CV-DG is available at Aetrix Electronics and suitable for industrial PLC I/O modules, analog sensor signal conditioning, split-supply audio preamps, and legacy industrial control boards requiring stable component supply and long-term obsolescence management.

Supply support for L7908CV-DG 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 ICs, sensors, and analog components for industrial, automotive, and consumer markets.

The L79xxC series belongs to ST's legacy linear regulator product line, engineered specifically for reliable, low-cost, fixed-output negative voltage regulation in space-constrained and thermally demanding industrial environments.

FAQ

What is the maximum input voltage rating for L7908CV-DG?

The absolute maximum DC input voltage is -35 V when regulating -8 V output, per Table 2 in ST Doc ID 2149 Rev 21. Operation above -23 V reduces safe output current due to power dissipation limits; sustained use above -25 V requires derating and thermal analysis to avoid junction temperature exceedance.

Does L7908CV-DG require external capacitors, and what types are recommended?

Yes: a minimum 2.2 µF solid tantalum capacitor on the input and 1 µF solid tantalum on the output are required for stability, as specified in Figure 4 and Section 6. Aluminum electrolytic capacitors may be used only if capacitance is increased tenfold (e.g., 22 µF input, 10 µF output) to maintain phase margin.

How does the "DG" suffix in L7908CV-DG differ from L7908CV?

The "DG" suffix denotes ST's Dual Gauge TO-220FP package variant, featuring reinforced leadframe construction for improved mechanical strength and solder joint reliability during thermal cycling. Electrically identical to L7908CV, it shares the same pinout, thermal specs (R_thJC = 5 °C/W), and electrical characteristics.

Can L7908CV-DG be used in adjustable configurations?

Yes-though designed as a fixed -8 V regulator, it can be configured for adjustable output using an external resistor divider between output and ground, as shown in Figure 6. The ADJ pin is not present; regulation relies on modifying the feedback path to the internal reference, requiring careful stability analysis and additional components.