Diodes Incorporated SMAJ8.5CA-13

Overview

SMAJ8.5CA-13 from Diodes Incorporated is a bi-directional 400W transient voltage suppressor (TVS) diode designed for primary-level overvoltage protection in DC power rails and signal lines. It features a 8.5V reverse standoff voltage (VRWM), 9.44–10.4V breakdown range (VBR @ 1mA), 14.4V max clamping voltage at 27.7A peak pulse current (IPP), and operates from –55°C to +150°C. Used in automotive body control modules to protect CAN transceiver I/O against ISO 7637-2 load dump and ESD.

For engineers reviewing the SMAJ8.5CA-13 datasheet, SMAJ8.5CA-13 pinout, SMAJ8.5CA-13 application, or SMAJ8.5CA-13 equivalent, key selection criteria include clamping voltage margin relative to protected IC's absolute maximum rating, bidirectional symmetry for AC-coupled interfaces, JEDEC-compliant 8.3ms surge capability, and RoHS-compliant matte tin termination compatibility with lead-free reflow profiles.

Technical Context

This bi-directional TVS uses glass-passivated silicon junctions to achieve fast response (<1 ps) to transient events while maintaining low leakage (<10 µA @ VRWM). Its symmetrical avalanche structure enables identical clamping behavior for both polarities-critical for protecting differential buses like RS-485 or USB D+/D– without polarity biasing concerns.

The device complies with IEC 61000-4-2 (±30 kV contact) and IEC 61000-4-5 (400W, 8/20 µs waveform), with thermal derating defined up to 175°C storage and 150°C operating junction temperature. Steady-state power dissipation is rated at 1.0W at TL = 75°C, and peak forward voltage is 3.5V at IPP = 35A.

Key Specifications

Pinout & Package

Two-terminal SMA (DO-214AC) package with cathode band omitted (bi-directional configuration). Dimensions: 4.00–4.60 mm length × 2.29–2.92 mm width × 1.27–1.63 mm height; weight ≈ 0.064 g.

Key Features

Applications

Availability

SMAJ8.5CA-13 is available at Aetrix Electronics and suitable for automotive infotainment power rails, industrial sensor node I/O protection, and USB-C port ESD hardening requiring stable component supply across extended temperature ranges and high-reliability production cycles.

Supply support for SMAJ8.5CA-13 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability protection, power management, and signal integrity solutions for automotive, industrial, and computing markets.

The SMAJ series belongs to Diodes' transient voltage suppression portfolio, engineered specifically for robust, standardized surge immunity in harsh environments where JEDEC-compliant 8.3ms surge handling and wide temperature operation are mandatory.

FAQ

What does the "C" suffix in SMAJ8.5CA-13 indicate?

The "C" denotes bi-directional functionality: the device exhibits identical breakdown and clamping characteristics for both positive and negative voltage transients. Unlike unidirectional variants (e.g., SMAJ8.5A), it has no cathode band marking and requires no polarity alignment during placement-ideal for AC-coupled or differential signal paths.

How does SMAJ8.5CA-13 compare to SMAJ8.5A in circuit implementation?

SMAJ8.5A is unidirectional and must be oriented with cathode toward the protected line's positive rail; SMAJ8.5CA-13 eliminates orientation constraints. Both share identical VRWM (8.5V), VBR (9.44–10.4V), and VC (14.4V), but only the "C" version supports symmetric surge suppression-critical for RS-485 or Ethernet PHY protection where polarity reversal occurs.

Is SMAJ8.5CA-13 suitable for protecting a 5V logic rail?

No-it is not recommended for 5V rails. With a 8.5V standoff voltage and 14.4V clamping, it activates too late to protect 5V-tolerant ICs (typically rated to 5.5–6.5V max). For 5V applications, use SMAJ5.0CA-13 (VRWM = 5.0V, VC = 9.2V) to ensure clamping occurs well below the protected device's absolute maximum rating.

Does SMAJ8.5CA-13 require a heatsink in typical PCB layouts?

No external heatsink is required. Its 1.0W steady-state power rating is intended for short-duration surges-not continuous dissipation. In standard FR-4 PCBs with ≥1 cm² of 1 oz copper connected to each terminal, thermal resistance is sufficient to handle JEDEC-defined 8.3ms pulses without exceeding 150°C junction temperature, provided ambient stays below 75°C.