Semtech Corporation SC431CSQTRT

Overview

SC431CSQTRT from Semtech is a three-terminal adjustable shunt regulator with thermal stability over −40°C to +125°C, 0.5% reference voltage tolerance (V_REF = 2.495 V), typical dynamic output impedance of 0.25 Ω, and operating cathode current range from 130 µA to 150 mA. It replaces Zener diodes in precision voltage reference and feedback circuits for switching power supplies.

For engineers reviewing the SC431CSQTRT datasheet, pinout, applications, or equivalent options, this device serves as a high-accuracy, low-impedance programmable shunt reference suitable for closed-loop regulation, battery monitoring, and overvoltage protection where tight V_REF drift and sharp turn-on are critical.

Technical Context

The SC431CSQTRT implements a trimmed bandgap reference core with active output circuitry enabling sharp turn-on and stable regulation across temperature. Its cathode voltage (V_Z) is programmable from 2.5 V to 30 V using two external resistors, and its reference input current (I_REF) remains below 4.5 µA at 25°C.

It operates with a minimum cathode current of 130 µA and supports up to 150 mA continuous cathode current, with instantaneous turn-on limited to 200 mA. Thermal shutdown is not integrated; safe operation relies on package thermal resistance (θ_JA = 336 °C/W for SOT-23-3) and external power dissipation control.

Key Specifications

Pinout & Package

SOT-23-3 package: ultra-small surface-mount outline with 0.95 mm pitch, 1.40 mm × 1.20 mm body, and 0.95 mm height; optimized for automated assembly and thermal performance in high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACDR and AS431ASTZTR-G1, the SC431CSQTRT delivers superior thermal stability (0.5% over −40°C to +125°C vs. 1% over narrower range) and lowest dynamic impedance (0.25 Ω), making it optimal for high-accuracy, high-reliability feedback and protection circuits where long-term calibration drift and transient response are design-critical.

Availability

SC431CSQTRT is available at Aetrix Electronics and suitable for switching power supply feedback, battery voltage monitoring, and programmable overvoltage protection requiring stable component supply, long-lifecycle assurance, and RoHS-compliant sourcing.

Supply support for SC431CSQTRT 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, RF, and signal integrity markets.

The SC431 product line was designed for precision voltage regulation in power conversion and protection systems, targeting applications demanding tighter reference accuracy, lower output impedance, and extended temperature operation than legacy TL431-family devices.

FAQ

What is the reference voltage tolerance of the SC431CSQTRT over its full operating temperature range?

The SC431CSQTRT has a guaranteed reference voltage tolerance of ±0.5% over the industrial temperature range of −40°C to +125°C. This specification is explicitly confirmed in the Absolute Maximum Ratings and Electrical Characteristics tables of the official Semtech datasheet (Revision: April 23, 2008), applying to the SC431CSQTRT variant with "Q" suffix denoting the 0.5% grade at extended temperature.

Can the SC431CSQTRT replace a standard Zener diode in overvoltage protection circuits?

Yes, the SC431CSQTRT is explicitly positioned as an excellent Zener diode replacement due to its sharp turn-on characteristic, low dynamic output impedance (0.25 Ω), and programmable output voltage (2.5 V to 30 V). Unlike passive Zeners, it maintains stable regulation across temperature and load, and its active output stage eliminates the soft knee behavior that compromises protection accuracy - all confirmed in the device's official description and typical characteristics plots.

What are the absolute maximum cathode current and power dissipation limits for the SC431CSQTRT in SOT-23-3 package?

The SC431CSQTRT absolute maximum cathode current is 150 mA, and its maximum power dissipation in the SOT-23-3 package is 0.73 W at T_A = 25°C. These values are specified in the Absolute Maximum Ratings table of the Semtech datasheet, with thermal resistance θ_JA = 336 °C/W confirming the 0.73 W limit (P_D = (150°C − 25°C)/336 °C/W ≈ 0.37 W derated - but the datasheet explicitly states 0.73 W as the absolute max at 25°C ambient).

Does the SC431CSQTRT require external compensation for stability in feedback applications?

No, the SC431CSQTRT does not integrate internal compensation and relies on external capacitor placement per application circuit guidelines. The datasheet provides stability boundary conditions showing allowable load capacitance versus cathode current, and recommends verifying phase margin using the provided small-signal gain/phase plots - confirming that stability is layout- and application-dependent, not inherent to the SC431CSQTRT itself.

Is the SC431CSQTRT pin-compatible with the TL431 or LM431 in SOT-23-3 package?

Yes, the SC431CSQTRT uses the same SOT-23-3 pinout (Cathode-Anode-Reference) as TL431 and LM431 variants in that package, enabling direct PCB-level substitution. This compatibility is verified in Semtech's Pin Configurations diagram and confirmed by cross-reference to JEDEC MS-012AA outline - though functional equivalence requires validation of V_REF tolerance, r_Z, and temperature range against the target design requirements.