STMicroelectronics L7824CT

Overview

L7824CT from STMicroelectronics is a three-terminal positive fixed-voltage linear regulator delivering 24 V ±2 % output at up to 1.5 A, featuring thermal overload protection, short-circuit protection, and safe operating area (SOA) protection. It operates with input voltages up to 40 V and is commonly used in industrial power supplies, local on-card regulation, and embedded system auxiliary rails where stable, low-noise DC voltage is required.

For engineers reviewing the L7824CT datasheet, L7824CT pinout, L7824CT application, or L7824CT equivalent, key selection considerations include dropout voltage (2 V @ 1 A), load regulation (≤100 mV over 5 mA–1.5 A), supply voltage rejection (54 dB @ 120 Hz), junction temperature range (−40 °C to 125 °C), and TO-220 package thermal resistance (R_thJA = 50 °C/W).

Technical Context

The L7824CT implements a monolithic bipolar linear regulator architecture with internal current limiting, thermal shutdown, and SOA protection-enabling robust operation without external protection circuitry. Its feedback loop maintains output regulation across line (VI = 27–38 V) and load (IO = 5 mA–1.5 A) variations while sustaining ≤24.5 V max output at 25 °C.

Designed for fixed-output use, it requires only two external capacitors (CI = 0.33 µF, CO = 0.1 µF) for stability and ripple suppression. The device exhibits 10 µV/√Hz output noise (10 Hz–100 kHz), 20 mΩ output resistance, and −1.5 mV/°C output voltage drift, making it suitable for noise-sensitive analog subsystems when adequately heatsinked.

Key Specifications

Pinout & Package

Supplied in TO-220 package (3-pin, vertical mounting, metal tab connected to GND), the L7824CT uses standard three-terminal configuration: Input (Pin 1), Ground (Pin 2), Output (Pin 3). The metal tab is electrically tied to Pin 2 (GND), enabling direct heatsink attachment with insulating hardware.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM7824K and MC7824BT, the L7824CT offers superior SOA protection and lower quiescent current, making it optimal for thermally constrained or inductively loaded 24 V systems-while maintaining identical pinout and footprint compatibility.

Availability

L7824CT is available at Aetrix Electronics and suitable for industrial power supplies, embedded system auxiliary rails, and test equipment requiring stable component supply with full traceability and lifecycle management.

Supply support for L7824CT 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 automotive, industrial, and power management ICs with strong European manufacturing and quality certification.

The L78 series belongs to ST's legacy linear regulator product line, designed specifically for cost-effective, robust local DC voltage regulation in industrial and embedded systems where simplicity, reliability, and thermal resilience are prioritized over efficiency.

FAQ

What is the minimum input voltage required for the L7824CT to regulate at full load?

The L7824CT requires a minimum input voltage of 27.3 V when delivering 1 A, per Table 9 in DS0422 Rev 38. This accounts for its 2 V dropout voltage plus margin for line regulation and thermal effects. At light loads (<50 mA), regulation may hold down to ~25.5 V, but design must ensure ≥27.3 V under worst-case conditions including ripple and temperature drift.

Can the L7824CT be used without a heatsink?

Yes, for short-duration or low-duty-cycle operation below ~500 mA at ambient temperatures ≤40 °C, as R_thJA = 50 °C/W allows ~1 W dissipation before reaching 125 °C junction limit. However, continuous 1 A operation at 25 °C ambient generates ~22 W (VI ≈ 32 V → P_D ≈ 8 W), requiring a heatsink rated ≤20 °C/W to stay within safe limits.

Does the L7824CT support adjustable output voltage configurations?

No-the L7824CT is a fixed-output device with internal resistor network setting 24 V. While the broader L78xx family can be adapted using external resistors per application note AN281, the L7824CT variant lacks the ADJ pin and is not designed for adjustment. For variable outputs, consider the LM317 or ST's L200 adjustable regulator instead.

How does the L7824CT handle reverse polarity or input overvoltage?

The L7824CT has no reverse-polarity protection and will be damaged if VI is applied backward relative to GND. Input overvoltage beyond 40 V absolute maximum rating risks junction breakdown. External protection-such as a series diode (for reverse polarity) and TVS clamp (for transients)-is mandatory in harsh environments per ST's application guidance in DS0422 Section 4.2.