STMicroelectronics L7924ACV

Overview

L7924ACV from STMicroelectronics is a fixed-output, three-terminal negative linear voltage regulator delivering -24 V at up to 1.5 A, featuring thermal overload protection, short-circuit current limiting, and output transition SOA protection. It operates with input voltages up to -40 V, supports local on-card regulation in split-supply systems, and is commonly used in industrial power supplies requiring stable dual-rail ±24 V operation.

For engineers reviewing the L7924ACV datasheet, L7924ACV pinout, L7924ACV application, or L7924ACV equivalent, this device is selected for high-reliability negative rail generation where dropout voltage (1.1 V @ 1 A), load regulation (±240 mV), output voltage accuracy (±2 %), junction temperature range (0–125 °C), and thermal resistance (R_thJA = 50 °C/W in TO-220) are critical design constraints.

Technical Context

The L7924ACV implements a monolithic PNP pass transistor architecture with internal current limiting, thermal shutdown, and safe operating area (SOA) protection during output transients. Its feedback loop maintains regulated output under varying line (VI = -27 V to -38 V) and load (IO = -5 mA to -1.5 A) conditions while compensating for junction temperature drift (-1 mV/°C).

It requires external input (CI ≥ 2.2 µF solid tantalum) and output (CO ≥ 1 µF) capacitors for stability and ripple rejection. The device is not internally compensated for adjustable configurations but supports external resistor networks to increase output voltage or boost current via external pass devices.

Key Specifications

Pinout & Package

Supplied in TO-220 package (3-pin, vertical mounting, metal tab connected to GND), with standard pin configuration: Pin 1 = Input (IN), Pin 2 = Ground (GND), Pin 3 = Output (OUT). Tab is electrically tied to Pin 2 and must be isolated from chassis unless GND reference is chassis-connected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM337T and MC7924CT, the L7924ACV offers tighter initial output tolerance (±2 % vs. ±4 % for MC7924CT), lower noise (400 µV vs. 800 µV), and optimized SOA protection for fast transient loads-making it preferred for precision analog and legacy system replacement where fixed output and proven reliability are prioritized.

Availability

L7924ACV is available at Aetrix Electronics and suitable for industrial power supplies, test equipment bias rails, audio amplifier split supplies, and legacy control panel retrofits requiring stable component supply with long-term lifecycle visibility.

Supply support for L7924ACV 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 L79xxAC series was developed specifically for robust, cost-effective local regulation in industrial and instrumentation systems-emphasizing thermal resilience, fault protection, and compatibility with complementary L78xxA positive regulators in dual-rail architectures.

FAQ

What is the minimum input voltage required for regulation with L7924ACV?

The minimum input voltage is determined by dropout: VI(min) = VO + Vd = -24 V + 1.1 V = -25.1 V. For reliable operation across temperature and load, ST recommends VI ≥ -27 V. Below this, regulation degrades and output sags proportionally to the deficit.

Can L7924ACV be used in surface-mount designs?

No-the L7924ACV is only offered in through-hole TO-220 package. ST does not manufacture a surface-mount variant of this specific part number. D2PAK variants (e.g., L7924ACD2T-TR) exist but are distinct order codes with different thermal and mounting requirements.

Does L7924ACV require an input bypass capacitor?

Yes-ST specifies a minimum 2.2 µF solid tantalum capacitor between IN and GND, placed within 1 cm of the device. Aluminum electrolytic capacitors may be used only if ≥22 µF and with appropriate ESR; omission risks oscillation or poor transient response.

How does thermal resistance affect maximum output current?

With R_thJA = 50 °C/W (TO-220, no heatsink), power dissipation PD = (VI – VO) × IO must keep junction temperature ≤125 °C. At VI = -33 V and VO = -24 V, max IO ≈ 1.1 A without heatsink; adding a 10 °C/W heatsink raises usable current to ~1.5 A at 25 °C ambient.