Texas Instruments LM320T-5.0

Overview

LM320T-5.0 from Texas Instruments is a three-terminal negative voltage regulator delivering a fixed −5.0 V output with up to 1.5 A load current, 15 W power dissipation, and input-output differential as low as 1 V. It features internal thermal shutdown, preset current limiting independent of temperature, and 54 dB ripple rejection at 120 Hz - used in dual-rail analog supplies, industrial instrumentation, and legacy telecom power rails.

For engineers reviewing the LM320T-5.0 datasheet, LM320T-5.0 pinout, LM320T-5.0 application, or LM320T-5.0 equivalent, key selection criteria include guaranteed −5.0 V output accuracy (±3%), low thermal feedback for stable line/load regulation, TO-220 package thermal resistance (4°C/W junction-to-case), and compatibility with solid tantalum or aluminum electrolytic output capacitors ≥25 μF.

Technical Context

The LM320T-5.0 operates as a monolithic series pass regulator with built-in current limiting and thermal overload protection. Its output voltage is internally trimmed and does not require external resistors, enabling drop-in use in fixed-negative supply designs.

It maintains regulation down to a 1 V input-output differential and achieves ≤75 mV load regulation (5 mA to 1.5 A) and ≤25 mV line regulation across −25 V to −7 V input range, with quiescent current held to 1–2 mA and <0.4 mA variation over full operating conditions.

Key Specifications

Pinout & Package

LM320T-5.0 uses a TO-220 (NDE) 3-pin power plastic package with metal tab connected to the input terminal. Mounting requires electrically isolated heatsinking due to tab-to-input connectivity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM337T-5.0 and LM7905CT, the LM320T-5.0 delivers tighter output voltage accuracy, lower quiescent current, higher ripple rejection, and guaranteed performance across the full 0°C to +125°C industrial temperature range - making it the preferred choice for mission-critical analog and telecom infrastructure designs.

Availability

LM320T-5.0 is available at Aetrix Electronics and suitable for industrial instrumentation, legacy telecom power distribution, and embedded control system backplanes requiring stable component supply with long lifecycle support.

Supply support for LM320T-5.0 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

Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, specializing in analog, embedded processing, and power management technologies.

The LM320-N series was designed specifically for ruggedized fixed-negative regulation in industrial, telecom, and test equipment where reliability, thermal robustness, and long-term stability outweigh cost sensitivity.

FAQ

What is the guaranteed output voltage tolerance for LM320T-5.0 over temperature?

The LM320T-5.0 guarantees −5.0 V output within ±3% (−4.85 V to −5.15 V) at TJ = 25°C, VIN = 10 V, and ILOAD = 5 mA. Over the full 0°C to +125°C junction temperature range, worst-case deviation remains bounded by line, load, and temperature effects per the datasheet's composite regulation spec - ensuring reliable operation in industrial environments without external trimming.

Can LM320T-5.0 operate with an input voltage of −6 V?

No. The LM320T-5.0 requires a minimum input-output differential of 1 V for regulation, meaning the input must be ≤−6.0 V to sustain −5.0 V output. However, its absolute maximum input voltage is −25 V, and its specified input range is −25 V to −7 V. At −6 V input, the device falls below the minimum differential and enters dropout - resulting in unregulated, input-following output behavior.

Is a heatsink required for LM320T-5.0 at 1.5 A output current?

Yes. With a junction-to-case thermal resistance of 4°C/W and 15 W maximum dissipation, even modest ambient temperatures require heatsinking. At 1.5 A and 3 V input-output differential (e.g., VIN = −8 V), power dissipation is 4.5 W - demanding a heatsink with ≤22°C/W junction-to-ambient resistance to hold TJ ≤125°C. The TO-220 metal tab must be electrically isolated if mounted to a conductive chassis.

What output capacitor value and type are mandatory for LM320T-5.0 stability?

A minimum 25 μF output capacitor is required for stability. The datasheet specifies solid tantalum for the nominal 25 μF value shown, but permits substitution with 25 μF aluminum electrolytic. Capacitance may be increased without limit; however, for >100 μF, a reverse-biased 1N4001 diode from input to output is required to protect against momentary input shorts.

Does LM320T-5.0 support adjustable output voltages?

No. The LM320T-5.0 is a fixed-output regulator with internally trimmed −5.0 V reference. While the broader LM120/LM320-N family includes variants that can be adjusted upward using external resistors (e.g., LM137), the LM320T-5.0 lacks the ADJ pin and internal architecture needed for programmability - it is strictly a 3-terminal fixed-negative regulator.