STMicroelectronics LM217D2T

Overview

LM217D2T from STMicroelectronics is a monolithic adjustable positive voltage regulator in D2PAK (TO-263) package, delivering ≥1.5A output current with 1.2V to 37V adjustable output range, 0.1% line/load regulation, and integrated thermal shutdown, current limiting, and SOA protection. It operates as a floating regulator for high-voltage applications such as lab power supplies and industrial DC rails.

For engineers reviewing the LM217D2T datasheet, LM217D2T pinout, LM217D2T application, or LM217D2T equivalent, key selection criteria include output voltage adjustability via resistive divider, minimum load current requirement (3.5–5 mA), reference voltage tolerance (1.2–1.3 V), thermal resistance (R_thj-amb = 62.5°C/W), and D2PAK mounting compatibility with high-power PCB layouts.

Technical Context

The LM217D2T implements a bandgap-referenced error amplifier driving a pass transistor, with all quiescent current returned to the output to maintain regulation under light loads. Its floating architecture allows operation with input-to-output differential up to 40 V, independent of ground potential.

It features internal current limiting set by SOA control, thermal shutdown triggered at T_j ≥150°C, and stable operation with ≥0.1 µF input bypass and ≥10 µF adjustment-to-ground capacitor. Output noise is 0.003% of V_O (10 Hz–10 kHz).

Key Specifications

Pinout & Package

LM217D2T uses the D2PAK (TO-263) surface-mount package with exposed thermal pad (pin 2) for enhanced heat dissipation. The package measures 15.0–15.85 mm length, 10.0–10.4 mm width, and 4.4–4.6 mm height, with gull-wing leads compatible with standard reflow profiles.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM317D2T, LM217D2T offers wider operating temperature and higher reliability in harsh environments; versus TLV1117-33CDR, it provides full adjustability and 1.5× output current but requires external components and larger thermal management.

Availability

LM217D2T is available at Aetrix Electronics and suitable for laboratory power supplies, industrial motor control bias rails, programmable LED drivers, and automotive aftermarket charging systems requiring stable component supply and long-term manufacturability.

Supply support for LM217D2T 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 analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The LM217 series belongs to ST's legacy linear regulator product line, engineered specifically for robust, high-current adjustable DC power conversion in industrial and test equipment where reliability and thermal resilience are critical.

FAQ

What is the minimum load current required for stable regulation with LM217D2T?

The LM217D2T requires a minimum load current of 3.5 mA (typical) to 5 mA (max) to maintain output regulation. This is due to its architecture returning all quiescent current to the output pin. If load current falls below this threshold-such as in standby or light-load conditions-the output voltage may rise uncontrollably. A bleeder resistor from OUT to GND is commonly used to guarantee compliance.

Can LM217D2T be used in a current-regulator configuration?

Yes. By connecting a fixed resistor R1 between ADJ and OUT, and leaving the ADJ node unconnected elsewhere, the device regulates current as I_OUT ≈ 1.25 V / R1. This exploits the constant 1.25 V reference between OUT and ADJ pins. For example, R1 = 2.5 Ω yields ~500 mA output. I_ADJ adds <5 µA error, making this method highly accurate for LED drivers and battery chargers.

What thermal considerations apply to LM217D2T in D2PAK package?

The D2PAK package has R_thj-amb = 62.5°C/W (max). At 1.5 A and 10 V dropout (15 W dissipation), junction temperature rise exceeds 900°C-physically impossible without heatsinking. Real-world use requires a 2–4 in² copper pour (2 oz) plus optional heatsink. Derate output current above 85°C ambient; thermal shutdown activates at 150°C junction temperature.

Is an input bypass capacitor mandatory for LM217D2T stability?

Yes. A minimum 0.1 µF ceramic capacitor placed within 5 mm of the IN pin is required to prevent oscillation and improve transient response. Larger values (e.g., 10 µF aluminum electrolytic) further reduce input ripple but do not replace the ceramic. Without it, the regulator may exhibit instability under dynamic load changes or high-frequency noise coupling from upstream converters.