STMicroelectronics L7809ABD2T

Overview

L7809ABD2T from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a fixed 9 V output with up to 1.5 A continuous current, ±2 % output voltage tolerance (A version), thermal overload and short-circuit protection, and operation across –40 °C to +125 °C junction temperature. It serves as a local on-card power supply in industrial control modules, automotive body electronics, and embedded microcontroller power rails.

For engineers reviewing the L7809ABD2T datasheet, L7809ABD2T pinout, L7809ABD2T application, or L7809ABD2T equivalent, key selection criteria include guaranteed extended-temperature operation, dropout voltage of 2 V at 1 A, load regulation ≤100 mV (5 mA–1.5 A), supply voltage rejection of 61 dB, and D²PAK package thermal resistance (R_thJC = 3 °C/W).

Technical Context

This device implements a monolithic series-pass linear regulator architecture with internal current limiting, safe-area protection, and thermal shutdown-enabling robust operation without external protection circuitry. Its fixed 9 V output is trimmed during manufacturing to ±2 % accuracy over temperature and load.

The L7809ABD2T requires only two external capacitors (0.33 µF input, 0.1 µF output) for stability and exhibits 18 mΩ output resistance at 1 kHz, supporting low-noise analog subsystems when paired with proper PCB layout and decoupling.

Key Specifications

Pinout & Package

The L7809ABD2T is housed in a surface-mount D²PAK (TO-263) package with three terminals: Input, Ground, and Output. This thermally enhanced package supports high-power dissipation with low junction-to-case thermal resistance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM340T-9.0/NOPB and MC7809BD2TR4G, the L7809ABD2T provides superior thermal performance in surface-mount form factor, guaranteed –40 °C start-up capability, and tighter ±2 % output accuracy-making it optimal for space-constrained, high-reliability embedded systems.

Availability

L7809ABD2T is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, and embedded microcontroller power rails requiring stable component supply, long-term lifecycle support, and AEC-Q100-aligned reliability.

Supply support for L7809ABD2T 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, specializing in power management, microcontrollers, and automotive ICs with vertical manufacturing and broad industrial qualification.

The L78 series belongs to ST's legacy positive voltage regulator product line, designed specifically for robust, low-cost, drop-in replacement of discrete regulator circuits in cost-sensitive and reliability-critical applications.

FAQ

What is the minimum input voltage required for stable 9 V output at 1.5 A?

The L7809ABD2T requires a minimum input voltage of 11.5 V under full load (1.5 A) and worst-case conditions (–40 °C), based on its 2 V dropout specification and 9 V output tolerance. At room temperature and 1 A load, 11 V suffices-but design margin mandates ≥11.5 V to guarantee regulation across temperature and production variation.

Can the L7809ABD2T be used without an input bypass capacitor?

No. The datasheet mandates a minimum 0.33 µF ceramic capacitor placed within 1 cm of the input pin to prevent high-frequency oscillation and ensure stability. Omitting this capacitor risks erratic output behavior, especially with long input traces or high-impedance sources like batteries or unregulated wall adapters.

How does thermal performance differ between D²PAK and TO-220 packages for this regulator?

The D²PAK (L7809ABD2T) has R_thJC = 3 °C/W versus TO-220's 5 °C/W, enabling ~40 % higher power dissipation before thermal shutdown at equal heatsink conditions. However, D²PAK's R_thJA is 62.5 °C/W vs. TO-220's 50 °C/W-so board-level copper area becomes critical for D²PAK to realize its junction-to-case advantage.

Is the L7809ABD2T compatible with lead-free reflow soldering processes?

Yes. The L7809ABD2T is RoHS-compliant and qualified for standard lead-free reflow profiles (JEDEC J-STD-020), including peak temperatures up to 260 °C for 30 seconds. Its D²PAK package uses matte tin plating and withstands multiple reflow cycles without degradation of thermal or electrical performance.