STMicroelectronics LM217LZ-AP

Overview

LM217LZ-AP from STMicroelectronics is a monolithic adjustable positive voltage regulator in TO-92 Ammopack packaging, delivering up to 100 mA output current with 1.2 V to 37 V adjustable output range, ±0.7% output voltage temperature stability, and integrated thermal overload and short-circuit protection. It operates in floating configuration for high-voltage applications such as industrial power supplies and programmable lab bench supplies.

For engineers reviewing the LM217LZ-AP datasheet, LM217LZ-AP pinout, LM217LZ-AP application, or LM217LZ-AP equivalent, key selection considerations include its 100 mA load capability, 1.25 V internal reference voltage, 0.01% typical line regulation, and TO-92 Ammopack mechanical compatibility with automated insertion systems.

Technical Context

The LM217LZ-AP 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 differentials up to 40 V while referencing only VO–ADJ = 1.25 V.

It features output transition safe-area compensation to prevent secondary breakdown during transient overloads, and uses external resistive feedback (R1/R2) to set VO = 1.25 V × (1 + R2/R1) + I_ADJR2, where I_ADJ ≤ 100 µA ensures predictable divider design.

Key Specifications

Pinout & Package

LM217LZ-AP is supplied in TO-92 Ammopack package (ECOPACK® compliant), with lead finish matte tin, Pb-free, and RoHS-compliant. The package has three leads arranged in standard TO-92 pinout orientation (bottom view): Pin 1 = ADJUST, Pin 2 = INPUT, Pin 3 = OUTPUT.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM317LZ-AP and TLV1117-33CDR, the LM217LZ-AP uniquely supports industrial temperature range, adjustable output, and floating operation - making it irreplaceable in programmable supplies and high-side biasing where voltage flexibility and wide ambient tolerance are mandatory.

Availability

LM217LZ-AP is available at Aetrix Electronics and suitable for industrial sensor signal conditioning, programmable bench power supplies, low-power microcontroller peripherals, and LED biasing applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant TO-92 Ammopack packaging.

Supply support for LM217LZ-AP 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 silicon solutions for automotive, industrial, and consumer markets with emphasis on energy efficiency and reliability.

The LM217L series belongs to ST's legacy linear regulator product line, engineered specifically for cost-sensitive, low-to-medium current applications demanding robustness, ease of use, and broad operating temperature support in through-hole packages.

FAQ

What is the minimum load current required for stable regulation with LM217LZ-AP?

The LM217LZ-AP requires a minimum load current of 3.5 mA (typical) to 5 mA (max) when VI–VO = 40 V, as specified in Table 4 of the datasheet. This ensures the internal quiescent current path remains complete and prevents uncontrolled output voltage rise due to insufficient sink at the OUTPUT pin.

Can LM217LZ-AP be used in a floating configuration for negative output generation?

No - the LM217LZ-AP is a positive adjustable regulator only. Its internal architecture references the ADJUST pin to OUTPUT, not ground. For negative outputs, use complementary devices like LM237 or LM337. Floating operation applies only to positive output configurations where the entire regulator "floats" above ground (e.g., high-side 24 V bias supply).

What is the purpose of the capacitor between ADJ and GND (CADJ) in LM217LZ-AP circuits?

A capacitor (typically 10 µF) between ADJ and GND improves ripple rejection by bypassing AC components on the reference node, increasing supply voltage rejection ratio (SVR) from 65 dB (no CADJ) to 66–80 dB. It also enhances transient response but must be non-polarized and placed close to the ADJ pin to avoid instability.

Does LM217LZ-AP require heat sinking in TO-92 Ammopack package?

At 100 mA output and VI–VO = 10 V, power dissipation is ~1 W. With TO-92 R_thJA = 200 °C/W, junction temperature rise would exceed safe limits without PCB copper heat-sinking. ST recommends using ≥6 cm² of 2-oz copper pour connected to Pin 2 (INPUT) and Pin 3 (OUTPUT) to achieve effective thermal relief per Table 3.