Diodes Incorporated BAS521-7

Overview

BAS521-7 from Diodes Incorporated is a high-voltage, ultra-fast switching diode in SOD-523 package, rated for 300 V repetitive peak reverse voltage, 250 mA forward current, and 50 ns reverse recovery time. It serves as a signal-level rectifier or clamping device in compact power management and interface protection circuits operating up to +150°C ambient.

For engineers reviewing the BAS521-7 datasheet, BAS521-7 pinout, BAS521-7 application, or BAS521-7 equivalent, key selection criteria include its 300 V V_RRM, 50 ns t_rr, 100 nA I_R at 5 V, SOD-523 footprint compatibility, and thermal resistance of 385 °C/W-critical for space-constrained, high-reliability DC-DC and ESD-critical signal paths.

Technical Context

This discrete silicon switching diode uses a planar epitaxial construction optimized for fast recovery and low leakage. Its 300 V V_RRM rating enables use in 24–48 V industrial bus interfaces, while the 50 ns t_rr supports PWM frequencies up to ~2 MHz in flyback snubbers and level-shift clamps.

The SOD-523 package delivers minimal parasitic capacitance (5 pF at 0 V) and low thermal resistance (385 °C/W), allowing operation at 150°C junction temperature with derated power dissipation-verified under JEDEC J-STD-020 Level 1 moisture sensitivity conditions.

Key Specifications

Pinout & Package

Package: SOD-523 - ultra-compact surface-mount plastic case (0.65 × 0.85 × 0.65 mm), matte tin-plated alloy 42 leadframe, cathode marked by bar on top surface, JEDEC-compliant Level 1 moisture sensitivity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage switching diode applications.

Compared with BAS16-7 and 1N4148W-7-F, the BAS521-7 uniquely balances 300 V capability with SOD-523 size and 50 ns speed-making it the only option for 48 V+ signal clamping where board area is constrained and moderate recovery speed is acceptable.

Availability

BAS521-7 is available at Aetrix Electronics and suitable for industrial sensor interfaces, 48 V DC-DC snubbers, and automotive LIN bus protection requiring stable component supply across multi-year production cycles.

Supply support for BAS521-7 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, headquartered in Plano, Texas, serving industrial, computing, consumer, and communications markets since 1964.

The BAS521 belongs to Diodes' high-voltage switching diode product line, engineered specifically for compact, high-reliability signal integrity and transient protection in space-limited 24–48 V systems.

FAQ

What is the maximum junction temperature for continuous operation?

The BAS521-7 is rated for continuous operation from –65°C to +150°C junction temperature. At 25°C ambient, its 325 mW power dissipation allows ~200 mW at 85°C ambient when mounted on FR-4 with recommended pad layout-per Figure 1 derating curve in DS32175 Rev. 6.

Is the BAS521-7 suitable for bidirectional ESD protection?

No-it is a unidirectional diode with cathode-bar marking. For bidirectional ESD clamping, Diodes Incorporated recommends the D3V3Z5U-7 (TVS array) or APx3201 (dual-rail ESD protector). The BAS521-7 functions only as a forward-conducting / reverse-blocking element.

Does the SOD-523 package support automated optical inspection (AOI)?

Yes-the SOD-523's cathode bar marking and consistent 0.65 mm body height enable reliable AOI detection using standard machine vision algorithms calibrated for 0402-class components. Diodes' packaging documentation confirms alignment with IPC-A-610 Class 2 visual acceptance criteria.

How does the 100 nA reverse leakage impact high-impedance sensor bias networks?

At 25°C and 5 V reverse bias, 100 nA leakage introduces <0.1 µV error in a 1 MΩ bias network-well within 16-bit ADC resolution. At 125°C, leakage rises to 150 µA per datasheet, increasing error to ~150 µV, which remains acceptable for most industrial 12–14 bit sensor front-ends.