Semtech Corporation SC431LCSK-.25TR

Overview

SC431LCSK-.25TR from Semtech is a three-terminal adjustable shunt regulator with ±0.25% reference voltage tolerance, 1.24 V to 20 V programmable output, and 0.05 Ω typical dynamic output impedance. It operates over –40°C to +125°C (industrial grade), supports cathode current from 100 µA to 100 mA, and replaces Zener diodes in precision voltage reference and error amplifier applications.

For engineers reviewing the SC431LCSK-.25TR datasheet, pinout, applications, or equivalent options, key selection criteria include reference voltage accuracy, thermal stability across temperature, low dynamic impedance for regulation loop integrity, and SOT-23-3 package compatibility with space-constrained power management circuits.

Technical Context

The SC431LCSK-.25TR implements a trimmed bandgap reference core with active output circuitry enabling sharp turn-on characteristics and stable regulation down to 1.24 V. Its internal architecture delivers low temperature drift (±20 ppm/°C typical) and maintains ±0.25% initial accuracy over the full industrial temperature range.

It functions as a two-input comparator driving a NPN output stage: the reference input (REF) compares against an external resistor divider, while the cathode (K) sinks current to regulate voltage at the anode (A). This topology enables use in feedback loops of switching regulators, linear supplies, and battery monitoring systems without requiring external compensation under proper load capacitance conditions.

Key Specifications

Pinout & Package

SOT-23-3 package: 3-pin, small-outline transistor outline with gull-wing leads; 1.3 mm × 2.9 mm footprint; 1.1 mm max height; JEDEC MS-012 compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431ACDBVR and AS431AMTR-E1, the SC431LCSK-.25TR offers superior initial accuracy (±0.25% vs. ±0.5%) and lower dynamic impedance (0.05 Ω vs. ≥0.1 Ω), making it preferred for high-precision feedback loops where regulation tightness and transient response are critical design parameters.

Availability

SC431LCSK-.25TR is available at Aetrix Electronics and suitable for switching power supply feedback, battery voltage monitoring, programmable linear regulation, and disk drive spindle control requiring stable component supply across industrial temperature ranges and long product lifecycles.

Supply support for SC431LCSK-.25TR 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

Semtech Corporation is a U.S.-based fabless semiconductor company specializing in high-performance analog and mixed-signal ICs for power management, protection, and signal integrity.

The SC431L series belongs to Semtech's precision voltage reference product line, designed specifically for high-accuracy shunt regulation in industrial, computing, and storage applications where thermal stability and tight initial tolerance are mandatory.

FAQ

What is the reference voltage tolerance of the SC431LCSK-.25TR?

The SC431LCSK-.25TR has a reference voltage tolerance of ±0.25% at 25°C, guaranteed over the full industrial temperature range (–40°C to +125°C). This tight tolerance is achieved through laser-trimmed bandgap circuitry and enables high-accuracy voltage setting in feedback networks. The SC431LCSK-.25TR maintains this specification without requiring external calibration or trimming during production.

Can the SC431LCSK-.25TR replace a Zener diode in my design?

Yes, the SC431LCSK-.25TR is explicitly designed as a high-performance replacement for Zener diodes in precision regulation applications. Its active output stage provides sharper turn-on, lower dynamic impedance (0.05 Ω vs. typical Zener's >10 Ω), and superior temperature stability. Unlike Zeners, the SC431LCSK-.25TR delivers consistent 1.24 V reference accuracy across its entire operating current range (100 µA to 100 mA).

What is the recommended load capacitance for stable operation of the SC431LCSK-.25TR?

Stability requires avoiding 10 nF to 1 µF capacitance directly across the SC431LCSK-.25TR cathode-anode terminals. Use either no capacitor (relying on remote load decoupling) or ≥10 µF local capacitance. This avoids oscillation during startup when cathode current passes through the instability region. The SC431LCSK-.25TR remains stable with ≤1 nF or ≥10 µF CL, per Semtech's Application Note on stability boundary conditions.

Does the SC431LCSK-.25TR support operation at low cathode currents?

Yes, the SC431LCSK-.25TR operates reliably down to 100 µA cathode current, enabling use in ultra-low-power applications such as battery-backed monitoring circuits and always-on supervisors. Its trimmed bandgap design ensures stable 1.24 V reference even at minimum current, unlike many Zener diodes that exhibit significant voltage drift below 1 mA.

Is the SC431LCSK-.25TR RoHS compliant and lead-free?

Yes, the SC431LCSK-.25TR is fully RoHS compliant and lead-free, meeting both WEEE and EU RoHS Directive 2011/65/EU requirements. The "T" suffix in the part number denotes lead-free packaging, and all terminations use matte tin plating. No lead content is present in the die, bond wires, or package mold compound.