onsemi LM317LBZ

Overview

LM317LBZ from onsemi is a 3-terminal adjustable positive voltage regulator in TO-92 package, delivering up to 100 mA output current with 1.2 V to 37 V programmable output range. It integrates internal current limiting, thermal shutdown, and safe-area compensation for robust local regulation in space-constrained PCBs. Used in low-power instrumentation, battery chargers, and embedded power rails where precision and fault resilience are required.

For engineers reviewing the LM317LBZ datasheet, pinout, applications, or equivalent options, key selection criteria include its 1.25 V reference voltage accuracy, ≤100 µA adjustment pin current, ±0.7% temperature stability over −40°C to +125°C, and TO-92 thermal resistance of 160°C/W (junction-to-ambient).

Technical Context

The LM317LBZ operates as a floating linear regulator, maintaining a precise 1.25 V reference between output and adjust terminals. Its feedback loop uses two external resistors (R1 = 240 Ω typical) to set output voltage via V_OUT = 1.25 V × (1 + R2/R1) + I_ADJR2, where I_ADJ is controlled below 100 µA to minimize error.

It employs bandgap-based reference generation, thermal foldback protection triggered at 180°C junction temperature, and safe-area compensated output transistor to prevent secondary breakdown under overload. Designed for operation with ≥3 V input-output differential, it supports floating configurations for high-side or high-voltage applications.

Key Specifications

Pinout & Package

LM317LBZ is housed in a Pb-free TO-92 (Case 29) plastic package with bent leads, rated for operation from −40°C to +125°C. Thermal resistance is 160°C/W (junction-to-ambient) at TA = 25°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM317LBZ, LM317LZG offers identical regulation performance in alternate packaging, while TLV1117-ADJ trades legacy compatibility for higher current and lower dropout-requiring PCB layout changes and load reassessment.

Availability

LM317LBZ is available at Aetrix Electronics and suitable for industrial sensor power supplies, programmable bench power modules, and USB-powered analog signal chains requiring stable component supply, long-term BOM continuity, and RoHS-compliant through-hole packaging.

Supply support for LM317LBZ 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

onsemi (formerly ON Semiconductor) is a global semiconductor manufacturer specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The LM317L family was designed for cost-sensitive, space-constrained linear regulation tasks-emphasizing ease of use, intrinsic fault protection, and wide output adjustability without external complexity.

FAQ

What is the minimum load current required for stable regulation with LM317LBZ?

The LM317LBZ requires a minimum load current of 3.5 mA (typical) to maintain regulation, especially when the input-output voltage differential exceeds 6.25 V. This ensures the internal bandgap reference remains active and prevents output voltage drift. For designs operating near this threshold, adding a bleeder resistor from Vout to ground is recommended to guarantee compliance across temperature and process variations.

Can LM317LBZ be used as a precision current regulator?

Yes, LM317LBZ can function as a precision current regulator by connecting a fixed resistor between the adjust and output terminals. With V_REF = 1.25 V, output current is I_OUT ≈ 1.25 V / R_SET. The LM317LBZ's low I_ADJ drift (≤5 µA) and ±0.7% temperature stability enable ±2% current accuracy over −40°C to +125°C, making it suitable for LED biasing and sensor excitation.

What thermal considerations apply to LM317LBZ in TO-92 package?

LM317LBZ in TO-92 has a junction-to-ambient thermal resistance of 160°C/W. At 100 mA output and 10 V dropout, power dissipation reaches 1 W, causing ~160°C junction rise above ambient-exceeding the 150°C absolute maximum. Derating is essential: limit continuous output current to ≤40 mA at 10 V dropout, or use copper pour heatsinking to reduce R_JA effectively.

Does LM317LBZ require input and output capacitors for stability?

LM317LBZ is internally compensated and stable without output capacitance. However, a 0.1 µF ceramic input capacitor (C_IN) is recommended to suppress high-frequency noise, and a 1 µF tantalum output capacitor (C_OUT) improves transient response. An optional 10 µF capacitor from adjust to ground (C_ADJ) enhances ripple rejection by ~15 dB at 120 Hz but is not required for basic stability.

How does the LM317LBZ differ from the automotive-grade NCV317LBZ?

The LM317LBZ and NCV317LBZ share identical electrical specifications and TO-92 packaging, but NCV317LBZ undergoes additional AEC-Q100 qualification, PPAP documentation, and enhanced process controls for automotive body electronics. LM317LBZ is intended for industrial and commercial applications; substituting it in automotive designs voids AEC-Q100 compliance unless fully requalified by the end customer.