STMicroelectronics LM237SP

Overview

LM237SP from STMicroelectronics is an adjustable three-terminal negative voltage regulator delivering up to −1.5 A across an output range of −1.2 V to −37 V. It features 0.01%/V typical line regulation, 0.3%/V typical load regulation, and 77 dB ripple rejection at 120 Hz. Designed for lab power supplies and industrial biasing circuits, it operates over 0 °C to 125 °C with internal current limit, thermal overload, and safe-area protection.

For engineers reviewing the LM237SP datasheet, LM237SP pinout, LM237SP application, or LM237SP equivalent, key selection criteria include guaranteed −1.5 A output current, TO-220 package thermal resistance (R_thJC = 3 °C/W), adjustment pin current (65–100 µA), and thermal regulation (0.003–0.04 %/W).

Technical Context

The LM237SP implements a bandgap-referenced error amplifier driving a PNP pass transistor in a closed-loop negative-feedback configuration. Its reference voltage is trimmed to −1.25 V (±3%) at 25 °C and exhibits 50 ppm/°C temperature coefficient.

Overload protection remains fully active even if the ADJ pin is disconnected. Line and load regulation performance exceeds fixed-voltage regulators due to high open-loop gain and low output impedance (< 20 mΩ at DC), enabling stable operation with minimal external components.

Key Specifications

Pinout & Package

LM237SP is housed in a TO-220 package with exposed metal tab (pin 2) for heatsink mounting and electrical connection to the output terminal. The package meets ECOPACK® environmental compliance standards and provides R_thJC = 3 °C/W and R_thJA = 70 °C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM337T, LM237SP offers identical regulation performance but with documented full-production status and enhanced supply-chain traceability; versus LT1033CS8, it delivers 15× higher output current at the cost of larger TO-220 footprint and lower PSRR.

Availability

LM237SP is available at Aetrix Electronics and suitable for laboratory power supplies, industrial process controllers, bipolar op-amp biasing, and programmable current sources requiring stable component supply across multi-year production cycles.

Supply support for LM237SP 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 microcontrollers, power management ICs, and analog devices for industrial, automotive, and consumer markets.

The LM237SP belongs to ST's legacy linear regulator product line, engineered specifically for high-reliability negative-voltage regulation in industrial test equipment and embedded control systems where thermal robustness and long-term stability are critical.

FAQ

What is the minimum input-to-output voltage differential required for proper regulation?

The LM237SP requires a minimum |V_IN − V_OUT| of 3 V for regulation across its full output range and temperature span. At −1.2 V output, this means V_IN must be ≤ −4.2 V; at −37 V output, V_IN must be ≤ −40 V. Dropout increases slightly at high junction temperatures, so design margins should include 0.5 V overhead.

Can the LM237SP be used in parallel for higher current output?

No-parallel operation is not supported. The LM237SP lacks built-in current-sharing features, and mismatched reference voltages or thermal gradients will cause unequal current distribution and potential thermal runaway. For >1.5 A, use an external PNP pass transistor with emitter-follower configuration and current-sense feedback.

Is a capacitor required on the ADJ pin for stability?

No capacitor is required on the ADJ pin. Stability is ensured by the input capacitor (≥1 µF tantalum or 10 µF aluminum) and optional output capacitor (≥1 µF). Adding capacitance to ADJ introduces phase lag that may degrade transient response and is not recommended per ST's application notes.

Does the metal tab of the TO-220 package connect internally to any pin?

Yes-the metal tab is internally connected to Pin 2 (OUT) and must be electrically isolated from the heatsink unless the output node is referenced to chassis ground. When mounting to a common heatsink shared with other regulators, use insulating shoulder washers and bushings rated for ≥200 V isolation to prevent short circuits.