Broadcom Limited ASSR-1520-002E

Overview

ASSR-1520-002E from Broadcom is a dual-channel, normally-off, solid-state SPST relay (Photo MOSFET) in a 300-mil DIP-8 package, rated for 60V output withstand voltage, 1.0A DC output current, and 0.2Ω typical on-resistance at 25°C. It functions as an optically isolated bidirectional signal switch for industrial control I/O isolation and EMR replacement.

For engineers reviewing the ASSR-1520-002E datasheet, pinout, applications, or equivalent options, key selection criteria include input LED drive compatibility (3 mA min), dual-channel independent switching, 3750 Vrms input-output isolation, and thermal derating behavior across –40°C to +85°C ambient.

Technical Context

The ASSR-1520-002E integrates an AlGaAs infrared LED optically coupled to a high-voltage detector circuit comprising a photovoltaic diode array and driver that controls two discrete high-voltage MOSFETs. Its dual-channel architecture enables independent SPST switching per channel with shared input-side logic.

It operates with CMOS-compatible input current (3–20 mA), achieves 0.27 ms typical turn-on time and 0.04 ms typical turn-off time at 5 mA drive, and maintains 1 μA max output leakage at 60 V with 0.8 pF input-output capacitance - critical for noise-sensitive analog and digital isolation interfaces.

Key Specifications

Pinout & Package

ASSR-1520-002E uses a 300-mil 8-pin DIP through-hole package (JEDEC MS-001AC), with 2.54 mm pitch, 9.65 mm width, and 7.62 mm height. Pin 1 is marked by a dot; pins 1–4 form one isolated input/output channel pair, and pins 5–8 form the second.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar solid-state relay applications.

Compared with ASSR-1520-002E, the TLP3548A offers compact SMT packaging but trades off higher on-resistance and slower switching, while the VO3120 provides superior isolation voltage at the cost of reduced current capacity and speed - making ASSR-1520-002E optimal for balanced performance in industrial DIP-based designs.

Availability

ASSR-1520-002E is available at Aetrix Electronics and suitable for industrial controls, factory automation, and data acquisition systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant through-hole relays.

Supply support for ASSR-1520-002E 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

Broadcom Inc. is a global semiconductor leader specializing in infrastructure software, networking, and optoelectronics solutions with emphasis on reliability and regulatory compliance.

The ASSR-15XX Series was designed specifically for high-current, high-reliability industrial signal isolation - replacing electromechanical relays with solid-state alternatives that deliver faster switching, zero contact bounce, and extended lifetime under cyclic load conditions.

FAQ

What is the minimum input current required to reliably turn on the ASSR-1520-002E?

The ASSR-1520-002E turns on with a minimum input current of 3 mA through its internal LED. For guaranteed operation across the full –40°C to +85°C temperature range and robust noise immunity, Broadcom recommends driving it with 5–10 mA. This ensures sufficient photovoltaic voltage generation to fully enhance both output MOSFETs in each channel, regardless of LED aging or temperature drift. The ASSR-1520-002E datasheet specifies this threshold in the Recommended Operating Conditions table.

Can the ASSR-1520-002E switch AC loads, and what are the limitations?

Yes, the ASSR-1520-002E supports bidirectional AC/DC switching per channel, with a 60 V peak output withstand voltage and 1.0 A RMS current rating. However, its AC capability is limited to low-frequency applications (≤60 Hz) due to lack of zero-crossing detection and potential capacitive coupling effects above 1 kHz. For pure AC loads, ensure voltage transients remain below 60 V peak and use external snubbers if inductive loads are present. The ASSR-1520-002E is not rated for mains-voltage direct switching.

What is the thermal derating behavior of the ASSR-1520-002E at elevated ambient temperatures?

The ASSR-1520-002E's maximum output current decreases linearly above 25°C ambient, reaching ~0.8 A at 60°C and ~0.6 A at 85°C for continuous DC operation - as shown in Figure 4 of the datasheet. This derating results from junction temperature limits (T_J ≤ 125°C) and the 0.2 Ω R_ON's self-heating. To maintain 1.0 A capability, keep ambient ≤40°C or add copper pour heat sinking. The ASSR-1520-002E's thermal resistance (θ_JA) is not explicitly specified, but its DIP-8 package relies on PCB copper area for dissipation.

Does the ASSR-1520-002E require external components for basic operation?

Yes - a series current-limiting resistor is mandatory on each input LED leg (pins 1–2 and 5–6) to set IF between 3–20 mA. No external gate resistors or flyback diodes are needed on the output side (pins 3–4 and 7–8) since the internal MOSFETs are fully integrated with driver circuitry. However, for inductive loads, a TVS diode or RC snubber across the output is recommended to suppress voltage spikes exceeding 60 V. The ASSR-1520-002E does not include built-in transient suppression.

How does the ASSR-1520-002E compare to electromechanical relays in terms of lifetime and reliability?

The ASSR-1520-002E offers vastly superior lifetime versus electromechanical relays: no moving parts, no contact wear, and no bounce - enabling >10⁹ operations versus ~10⁵–10⁶ for EMRs. Its MTBF exceeds 1 million hours at 25°C, and it maintains consistent R_ON and timing over life. Unlike EMRs, the ASSR-1520-002E is immune to vibration, shock, and magnetic fields. However, it cannot switch higher voltages (>60 V) or currents (>1 A) like larger EMRs, so the ASSR-1520-002E is best suited for signal-level and medium-power isolation tasks.