onsemi 1SMA13CAT3

Overview

1SMA13CAT3 from ON Semiconductor is a bidirectional 400 W peak power Zener transient voltage suppressor (TVS) designed for clamping high-energy transients in DC power rails and signal lines. It features a 13 V working peak reverse voltage (VRWM), 15.16 V nominal breakdown voltage (VBR) at 1 mA, 21.5 V clamping voltage (VC) at 18.6 A peak pulse current (IPP), and <1 ns response time - deployed in automotive power supplies and industrial control I/O protection.

For engineers reviewing the 1SMA13CAT3 datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM ≥ circuit operating voltage, VC margin relative to protected IC absolute maximum ratings, surge current capability under 10/1000 µs waveform, and junction capacitance (455 pF at 0 V) for high-speed signal line compatibility.

Technical Context

This device operates as a bidirectional Zener-based TVS diode, leveraging avalanche breakdown to clamp both positive and negative transients without polarity dependence. Its flat handling surface and low-profile SMA package support automated placement and thermal dissipation on FR-4 PCBs with minimum recommended footprint.

It delivers 400 W peak pulse power per 10/1000 µs waveform at TL = 25°C, with thermal resistance of 50 °C/W (junction-to-lead) and 250 °C/W (junction-to-ambient). ESD robustness exceeds 16 kV per Human Body Model (HBM), meeting IEC 61000-4-2 Level 4 requirements when properly laid out.

Key Specifications

Pinout & Package

The 1SMA13CAT3 is a two-terminal bidirectional TVS diode housed in an SMA (DO-214AC) package. Polarity is non-directional; cathode notch does not indicate functional polarity. Mounting position is unrestricted.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar transient suppression applications.

Compared with 1SMA13CAT3, SZ1SMA13CAT3G adds automotive qualification overhead without electrical trade-offs, while 1.5SMC13CA trades compactness for higher surge endurance - making 1SMA13CAT3 optimal for cost-sensitive, space-constrained 12 V systems requiring verified 400 W clamping.

Availability

1SMA13CAT3 is available at Aetrix Electronics and suitable for automotive electronics, industrial PLC I/O modules, medical diagnostic equipment, and telecom infrastructure requiring stable component supply and consistent surge performance across production batches.

Supply support for 1SMA13CAT3 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

ON Semiconductor is a global semiconductor manufacturer specializing in power management, analog, sensor, and discrete solutions for automotive, industrial, and communications markets.

The 1SMAxxCAT3G series belongs to ON Semiconductor's SURMETIC® TVS portfolio, engineered specifically for high-reliability transient suppression in harsh environments where fast response, repeatable clamping, and long-term stability are critical.

FAQ

What is the maximum clamping voltage of the 1SMA13CAT3 under standard surge conditions?

The 1SMA13CAT3 exhibits a maximum clamping voltage (VC) of 21.5 V when subjected to its rated peak pulse current of 18.6 A, measured using the standardized 10/1000 µs double-exponential waveform. This value is guaranteed across temperature and lifetime, and defines the upper voltage limit imposed on protected circuitry during transient events. The 1SMA13CAT3 maintains this clamping performance without degradation under repeated surges within its specified derating curve.

Is the 1SMA13CAT3 suitable for protecting high-speed data lines such as USB 2.0 or RS-485?

The 1SMA13CAT3 has a junction capacitance of 455 pF at 0 V bias, which introduces significant signal distortion on full-speed USB 2.0 (480 Mbps) or RS-485 links operating above ~10 Mbps. It is appropriate for lower-speed digital I/O, power rails, or analog sensor inputs where bandwidth is below 1 MHz. For high-speed data lines, lower-capacitance alternatives like the NUP4105MR6T1G (12 pF) should be evaluated instead of the 1SMA13CAT3.

Does the 1SMA13CAT3 have polarity markings, and how should it be oriented on the PCB?

The 1SMA13CAT3 features a cathode band marking on one end of the SMA package, but as a bidirectional TVS, this marking does not dictate functional polarity - either terminal may connect to the protected line or ground. Orientation is non-critical; the device clamps symmetrically for both positive and negative transients. The marking exists solely for mechanical alignment consistency during automated placement, not electrical directionality.

What is the thermal derating behavior of the 1SMA13CAT3 above 75°C ambient temperature?

The 1SMA13CAT3's DC power dissipation is rated at 1.5 W at TL = 75°C, with linear derating of 20 mW/°C above that temperature. Its peak pulse power remains 400 W for single-event transients regardless of ambient, but repetitive surges require thermal management to avoid junction overheating. PCB copper area and airflow must be validated per ON Semiconductor's recommended footprint (Case 403D) to sustain performance at elevated temperatures.

How does the 1SMA13CAT3 compare to unidirectional TVS diodes like the 1SMA13AT3G?

The 1SMA13CAT3 provides symmetrical clamping for AC signals and floating nodes, whereas the unidirectional 1SMA13AT3G only clamps positive transients and conducts reverse leakage like a standard diode. In DC-biased circuits where polarity is fixed, the 1SMA13AT3G offers lower leakage (<1 µA vs. 2.5 µA) and slightly tighter VBR tolerance. The 1SMA13CAT3 is preferred when signal inversion, differential pairs, or undefined polarity exist - no design change replaces 1SMA13CAT3 with 1SMA13AT3G without verifying bias conditions.