Skyworks Solutions Inc. SI8405AA-A-IS1R

Overview

SI8405AA-A-IS1R from Silicon Labs is a 16-pin SOIC narrow-body bidirectional I²C isolator with two additional unidirectional digital channels, delivering 2500 VRMS galvanic isolation, 1.7 MHz I²C bus support, and 35 mA SCL/SDA sink capability on Side B - used to isolate SMBus interfaces in Power over Ethernet (PoE) controllers and isolated SMPS systems with PMBus.

For engineers reviewing the SI8405AA-A-IS1R datasheet, SI8405AA-A-IS1R pinout, SI8405AA-A-IS1R application, or SI8405AA-A-IS1R equivalent, this page provides verified technical context, real-world timing behavior, safety-certified isolation parameters, and validated alternative options for legacy design continuity and I²C/SMBus signal integrity assurance.

Technical Context

The SI8405AA-A-IS1R implements RF-based on/off keying across a semiconductor isolation barrier, enabling latch-free bidirectional SDA/SCL operation without external anti-latch circuitry. Its A-side I²C inputs feature 450–780 mV logic thresholds and 910 mV max VOL at 3 mA, while B-side outputs deliver 35 mA sink current and 0.4 V max VOL at 35 mA - ensuring reliable open-drain bus compatibility.

Two unidirectional non-I²C channels operate at up to 10 Mbps with 20 ns propagation delay, 12 ns pulse width distortion, and 85 Ω nominal output impedance. Both sides include independent UVLO (2.15–2.5 V trip, 45–95 mV hysteresis), 25 kV/µs CMTI, and hot-swap protection against unpowered insertion into live systems.

Key Specifications

Pinout & Package

SI8405AA-A-IS1R is housed in a 16-pin narrow-body SOIC package (7.5 mm × 10.3 mm, 1.27 mm pitch) with creepage/clearance ≥4.01 mm and 560 V_PEAK working voltage per IEC 60747-5-2.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C isolator applications.

Compared with ADUM1250ARZ and ISO1540DR, SI8405AA-A-IS1R uniquely combines 2500 VRMS isolation, 1.7 MHz I²C speed, and dual unidirectional channels in a single 16-pin SOIC - making it the only option among the three that supports integrated interrupt/reset signaling alongside full-speed isolated I²C without external components.

Availability

SI8405AA-A-IS1R is available at Aetrix Electronics and suitable for Power over Ethernet (PoE), isolated SMPS, motor control monitoring, and intelligent power distribution unit applications requiring stable component supply and long-term lifecycle support.

Supply support for SI8405AA-A-IS1R 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

Silicon Labs is a fabless semiconductor company specializing in precision timing, isolation, and wireless SoCs for industrial, automotive, and infrastructure markets.

The Si840x family was designed specifically to replace optocouplers in I²C/SMBus isolation applications - emphasizing latch-free operation, low propagation delay, and regulatory-compliant reinforced insulation for safety-critical systems.

FAQ

What is the maximum I²C bus frequency supported by SI8405AA-A-IS1R?

SI8405AA-A-IS1R supports I²C bus frequencies up to 1.7 MHz, as confirmed in Table 6 of the official datasheet. This enables full-speed operation compliant with I²C Fast Mode Plus (Fm+) and SMBus 2.0 specifications. The timing is validated across –40 °C to +125 °C and 3.0–5.5 V supply range, with propagation delays ranging from 9 ns to 35 ns depending on voltage and edge direction. SI8405AA-A-IS1R maintains signal integrity at this rate without external anti-latch circuitry.

Does SI8405AA-A-IS1R require external components for I²C bus operation?

No, SI8405AA-A-IS1R requires only standard I²C pull-up resistors on both sides - no external anti-latch diodes, RC networks, or level shifters are needed. Its integrated latch-free architecture uses asymmetric input/output thresholds (e.g., Side A VOL > Side A VIL) to prevent bus lockup during clock stretching. SI8405AA-A-IS1R also includes internal UVLO and hot-swap protection, eliminating reliance on external supervisors or TVS devices for basic robustness.

What safety certifications apply to SI8405AA-A-IS1R?

SI8405AA-A-IS1R is certified to UL 1577 (2500 VRMS, 1 min), CSA Component Acceptance Notice 5A (IEC 60950-1/61010-1), and VDE IEC 60747-5-2 (560 V_PEAK working voltage). These cover reinforced insulation for industrial and telecom equipment. Certification testing includes production-level 3000 VRMS hipot screening, 25 kV/µs CMTI validation, and 60-year lifetime modeling at rated voltage - all documented in Tables 6–9 of the datasheet.

Can SI8405AA-A-IS1R's unidirectional channels interface with standard CMOS logic?

Yes, SI8405AA-A-IS1R's two unidirectional channels (CH1/CH2) are fully compatible with standard 3.3 V or 5 V CMOS logic. They feature VIH ≥ 2.0 V, VIL ≤ 0.8 V, VOH ≥ 4.8 V (at –4 mA), and VOL ≤ 0.4 V (at 4 mA), with 85 Ω nominal output impedance. These specs allow direct connection to microcontroller GPIOs, FPGA I/O banks, or ASIC control inputs without level translation - supporting up to 10 Mbps data rates with 20 ns propagation delay.

Is SI8405AA-A-IS1R recommended for new designs?

No - Silicon Labs explicitly marks SI8405AA-A-IS1R as "Not Recommended for New Designs" in Rev. 1.6 of the datasheet (dated October 2013). It remains available for legacy program continuity and last-time buy scenarios, but designers should evaluate newer alternatives like Si86xx or Si87xx families for improved power efficiency, higher CMTI (>100 kV/µs), and extended temperature support. SI8405AA-A-IS1R continues to be supported for existing production with full datasheet compliance and traceable sourcing.