onsemi SA160A

Overview

SA160A from Fairchild Semiconductor is a unidirectional 500 W transient voltage suppressor (TVS) diode designed for primary overvoltage protection in DC power lines and signal interfaces. It features a 160 V reverse stand-off voltage (VRWM), 178–197 V breakdown voltage (VBR), 259 V clamping voltage at peak pulse current, and operates up to +175 °C junction temperature - deployed in industrial power supplies and telecom surge protection circuits.

For engineers reviewing the SA160A datasheet, pinout, applications, or equivalent options, key selection criteria include clamping performance under 10/1000 μs surges, low leakage (<1.9 μA at VRWM), glass-passivated junction reliability, DO-15 package compatibility, and bidirectional variant availability (SA160CA).

Technical Context

The SA160A uses a planar, glass-passivated silicon junction optimized for fast transient response (<1.0 ps rise time from 0 V to VBR) and low incremental surge resistance. Its unidirectional polarity enables precise anode-to-ground or cathode-to-rail placement in DC-biased protection paths.

Rated for 500 W peak pulse power on the standardized 10/1000 μs waveform, it delivers 19.2 A peak pulse current (IPPM) while maintaining 259 V maximum clamping voltage - ensuring robust coordination with downstream fuses and upstream MOVs in multi-stage protection architectures.

Key Specifications

Pinout & Package

SA160A is housed in a DO-15 axial-leaded package with cathode indicated by a color band. The device has two terminals: anode and cathode. Polarity must be observed during PCB layout to ensure correct unidirectional clamping behavior.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SA160A, SMAJ160A offers equivalent protection with minor clamping variance but lower surge current capacity, while SMA6J160A delivers identical electrical performance in a thermally superior SMT package - enabling layout flexibility at the cost of mounting method change.

Availability

SA160A is available at Aetrix Electronics and suitable for industrial power supplies, telecom line cards, automotive body control modules, and renewable energy inverter monitoring circuits requiring stable component supply and long-lifecycle support.

Supply support for SA160A 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

Fairchild Semiconductor was a leading designer and manufacturer of high-performance analog and discrete semiconductors, acquired by ON Semiconductor in 2016; its legacy TVS portfolio remains widely deployed and supported.

The SAxxxA series was engineered specifically for robust, cost-effective transient suppression in DC power systems - emphasizing high pulse power, stable clamping, and reliability under thermal and surge stress.

FAQ

What is the maximum clamping voltage of SA160A at its rated peak pulse current?

The SA160A exhibits a maximum clamping voltage (VC) of 259 V when subjected to its rated peak pulse current of 19.2 A on the 10/1000 μs waveform. This value is measured per industry-standard IEC 61000-4-5 test conditions and defines the upper voltage limit imposed on protected circuitry during surge events. The SA160A maintains this clamping performance consistently across its specified operating temperature range.

Is SA160A unidirectional or bidirectional, and how does that affect circuit placement?

SA160A is a unidirectional TVS diode, meaning it conducts only when the cathode voltage exceeds the breakdown threshold relative to the anode. This requires correct orientation: cathode connects to the protected line, anode to ground or low-side reference. Incorrect polarity prevents clamping. For bidirectional protection, the SA160CA variant must be used instead - it lacks a cathode band and protects both polarities equally.

What is the reverse leakage current of SA160A at its rated stand-off voltage?

At its 160 V reverse stand-off voltage (VRWM), the SA160A specifies a maximum reverse leakage current (IR) of 1.9 μA at 25 °C. This low leakage ensures minimal power loss and no interference with high-impedance sensing or bias networks. Leakage increases with temperature but remains below 10 μA up to 125 °C, as confirmed in Fairchild's typical characteristics curves.

Can SA160A be used in place of SA160CA in a bidirectional surge protection design?

No - SA160A cannot replace SA160CA in bidirectional applications. SA160A is unidirectional and blocks reverse voltage beyond VRWM but conducts only in one direction; applying negative transients will not trigger clamping. SA160CA contains back-to-back diodes and protects both polarities. Substituting SA160A risks unprotected negative surges and potential system failure. Always match polarity type to application requirements.

What is the thermal derating behavior of SA160A above 75 °C ambient?

SA160A's steady-state power dissipation derates linearly above 75 °C ambient: from 1.0 W at 75 °C down to zero at 175 °C junction temperature. Derating follows the curve in Figure 5 of the datasheet, with a slope of approximately 11.1 mW/°C. This applies only to continuous DC power - peak pulse power (500 W) remains unaffected by ambient temperature per the 10/1000 μs rating definition.