Texas Instruments LM237KCE3

Overview

LM237KCE3 from Texas Instruments is a TO-220 packaged, adjustable 3-terminal negative-voltage regulator delivering up to –1.5 A output current across an adjustable range of –1.2 V to –37 V. It features internal current limiting, thermal shutdown, and safe-area compensation, and is used in precision negative power supplies for industrial instrumentation and analog signal chains.

For engineers reviewing the LM237KCE3 datasheet, LM237KCE3 pinout, LM237KCE3 application, or LM237KCE3 equivalent, key selection criteria include its –1.25 V reference voltage (OUTPUT-to-ADJUST), ±0.3% typical output regulation, 77 dB ripple rejection at 120 Hz with 10 µF ADJ capacitor, –25°C to +150°C operating junction temperature, and TO-220 thermal resistance of 24.8°C/W.

Technical Context

The LM237KCE3 implements a monolithic bandgap-referenced error amplifier driving a PNP pass transistor, with feedback taken from the ADJUSTMENT pin referenced to OUTPUT. Its architecture delivers stable negative regulation without external compensation beyond standard input/output capacitors.

It operates exclusively in adjustable-output mode: the ADJUSTMENT pin maintains a fixed –1.25 V relative to OUTPUT, enabling precise voltage setting via resistor divider (R1–R2). Protection functions-thermal shutdown and current limiting-are fully integrated and active across the full operating temperature range.

Key Specifications

Pinout & Package

LM237KCE3 uses the standard TO-220 (KC) package: 3-pin, through-hole, vertical mounting with metal tab electrically connected to INPUT pin and thermally coupled to PCB copper for heat dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM237KCE3, LM337KCE3 trades extended cold-start capability for lower cost in milder environments, while LM237KCSE3 provides identical performance with updated packaging and environmental compliance-making it the recommended upgrade path for production designs.

Availability

LM237KCE3 is available at Aetrix Electronics and suitable for industrial instrumentation, embedded analog subsystems, and programmable power supply designs requiring stable component supply and long-lifecycle support.

Supply support for LM237KCE3 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 leader specializing in analog, embedded processing, and power management technologies.

The LM237KCE3 belongs to TI's LMx37 family of adjustable negative regulators, designed specifically for robust, high-reliability negative voltage generation in industrial, test, and measurement equipment where wide temperature operation and built-in protection are essential.

FAQ

What is the minimum input-to-output voltage differential required for stable operation of the LM237KCE3?

The LM237KCE3 requires a minimum input-to-output differential voltage of –2.5 V to maintain regulation. This means if the desired output is –12 V, the input must be no higher than –14.5 V (i.e., more negative). Operation below this threshold risks dropout and loss of regulation, especially under load. The LM237KCE3 datasheet specifies this as |VI – VO| ≥ 2.5 V in Recommended Operating Conditions.

Can the LM237KCE3 be used in parallel for higher current output?

No, the LM237KCE3 is not designed for direct parallel operation due to mismatch in reference voltage and output impedance, which causes unequal current sharing and potential thermal runaway. For higher current, use a single higher-rated regulator or implement external current-sharing circuitry with ballast resistors and matched devices-though this is not recommended without validation per TI Application Report SLVA492.

What capacitor values are mandatory for stable operation of the LM237KCE3?

A 1 µF solid tantalum capacitor is mandatory on the OUTPUT pin for stability; a 0.1 µF ceramic or film capacitor is recommended on the INPUT pin. If the LM237KCE3 is placed more than 10 cm from the main filter capacitor, a second 1 µF solid tantalum capacitor is required on INPUT. These values are specified in Section 10 (Power Supply Recommendations) and Figure 3 of the LM237/LM337 datasheet SLVS047L.

Does the LM237KCE3 require a minimum load current to maintain regulation?

Yes, the LM237KCE3 requires a minimum output current of 2.5 mA to 10 mA (depending on |VI – VO| and temperature) to maintain regulation. At |VI – VO| ≤ 15 V and TJ = 25°C, the minimum is 1.5 mA; at |VI – VO| ≤ 40 V, it rises to 2.5 mA. This is documented in the "Minimum output current to maintain regulation" parameter in Section 7.5 of the datasheet.

How does the ADJUSTMENT pin function in the LM237KCE3?

The ADJUSTMENT pin of the LM237KCE3 maintains a fixed –1.25 V potential relative to the OUTPUT pin. It serves as the feedback reference for the internal error amplifier. Connecting a resistor divider (R1–R2) between OUTPUT and ADJUSTMENT sets the output voltage per VO = –1.25 V × (1 + R2/R1). This relationship is derived from the device's internal bandgap reference and is validated across temperature and load in the datasheet's Electrical Characteristics table.