Texas Instruments LM337KTPR

Overview

LM337KTPR from Texas Instruments is a 3-terminal adjustable negative-voltage regulator delivering up to –1.5 A output current over an adjustable range of –1.2 V to –37 V, featuring 0.3% typical output regulation, 77 dB typical ripple rejection at 120 Hz with 10 µF ADJ capacitor, and internal thermal shutdown and current limiting. It serves as a precision local regulator in industrial power supplies requiring stable negative bias rails.

For engineers reviewing the LM337KTPR datasheet, LM337KTPR pinout, LM337KTPR application, or LM337KTPR equivalent, key selection criteria include its TO-252 (KVU) package thermal performance (R_θJA = 30.3°C/W), –1.25 V reference voltage between OUTPUT and ADJUSTMENT pins, minimum load current requirement (1.5 mA at |V_I–V_O| ≤10 V), and compatibility with standard resistor-divider output programming.

Technical Context

The LM337KTPR implements a bandgap-referenced error amplifier driving a PNP pass transistor, with feedback taken from the ADJUSTMENT pin referenced to OUTPUT. Its architecture enables precise negative output adjustment via external R1/R2 divider while maintaining stability with ≥1 µF output capacitance.

It operates within 0°C to +125°C junction temperature range and requires |V_I–V_O| between –2.5 V and –37 V for regulation. Protection features include thermal shutdown triggered above 150°C virtual junction temperature and foldback current limiting active during overload or short-circuit conditions.

Key Specifications

Pinout & Package

LM337KTPR uses the TO-252 (KVU) surface-mount package: 3-pin, single-row, exposed thermal pad on underside, body size 6.6 mm × 6.10 mm, JEDEC MO-155 compliant. The thermal tab is electrically connected to the INPUT pin and must be soldered to a PCB copper pour for thermal management.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM337KTPR, LM337KTTR offers lower thermal resistance for higher power density, while LM337KVURG3 provides identical performance in a RoHS-compliant, actively manufactured TO-252 variant - both require no schematic change but differ in layout and procurement status.

Availability

LM337KTPR is available at Aetrix Electronics and suitable for industrial power supplies, test equipment, audio amplifiers, and programmable current sources requiring stable component supply and long-term BOM continuity.

Supply support for LM337KTPR 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, designing and manufacturing analog ICs, embedded processors, and system-on-chip solutions for industrial, automotive, and consumer markets.

The LM337KTPR belongs to TI's legacy LMx37 family of adjustable negative regulators, engineered for robust local regulation in harsh environments where reliability, thermal resilience, and precision under variable load are critical.

FAQ

What is the correct pin configuration for LM337KTPR in the TO-252 package?

The LM337KTPR in TO-252 (KVU) package has three pins: Pin 1 is ADJUSTMENT, Pin 2 is OUTPUT, and Pin 3 is INPUT. When viewing the top side with marking visible and leads pointing downward, the leftmost pin is ADJUSTMENT, center is OUTPUT, and rightmost is INPUT. The thermal pad underneath is internally connected to INPUT and must be soldered to a PCB ground or input plane for thermal conduction.

Can LM337KTPR be used as a precision current regulator?

Yes, LM337KTPR can function as a precision current regulator by connecting the load between the ADJUSTMENT and OUTPUT pins, with a sense resistor (R_S) from OUTPUT to ground. Since the ADJUSTMENT pin maintains –1.25 V relative to OUTPUT, the current through R_S is I_OUT = 1.25 V / R_S. This configuration achieves <1% accuracy over temperature and load, as confirmed in TI's SLVS047L datasheet Section 9.1.1.

What are the minimum and maximum input-to-output differential voltage requirements for LM337KTPR?

LM337KTPR requires |V_I–V_O| between –2.5 V (minimum dropout) and –37 V (maximum differential) for proper regulation. Operation outside this range risks loss of regulation or device damage. At |V_I–V_O| ≤ –2.5 V, the part cannot maintain output accuracy; above –37 V, absolute maximum ratings are exceeded per Section 7.1 of the SLVS047L datasheet.

Is LM337KTPR still in active production?

No, LM337KTPR is marked OBSOLETE in TI's official packaging addendum (dated 22-Aug-2014). TI discontinued manufacturing LM337KTPR; however, Aetrix Electronics maintains legacy inventory with full traceability. For new designs, TI recommends LM337KVURG3 - an identical TO-252 variant with green RoHS compliance and active production status.

What output capacitor is required for stable operation of LM337KTPR?

LM337KTPR requires a minimum 1 µF solid tantalum capacitor or 10 µF aluminum electrolytic capacitor on the OUTPUT pin for stability, as specified in Sections 9.2.1 and 10 of the SLVS047L datasheet. Ceramic capacitors alone are insufficient due to ESR requirements; if used, they must be paralleled with ≥1 µF tantalum or polymer capacitor to meet minimum ESR and capacitance targets.