onsemi NP3500SBT3G

Overview

NP3500SBT3G from onsemi is a bidirectional thyristor surge protector (TSPD) designed for overvoltage clamping in telecom line interfaces. It features 320 V peak off-state voltage (V_DRM), 400 V breakover voltage (V_BO), 4 V on-state voltage (V_T), 150 mA holding current (I_H), and supports 500 A_(pk) 10×1000 µs surge current per GR-1089-CORE. It protects central office, access, and customer premises equipment.

For engineers reviewing the NP3500SBT3G datasheet, pinout, applications, or equivalent options, key selection criteria include bidirectional crowbar action, SMB package compatibility, GR-1089-CORE/IEC 61000-4-5 compliance, low capacitance (28 pF), and thermal resistance of 90 °C/W.

Technical Context

The NP3500SBT3G operates as a voltage-triggered crowbar device: when transient voltage exceeds 400 V in either polarity, it latches into low-impedance conduction until current falls below 150 mA. Its 5 kV/µs critical dv/dt rating ensures stable blocking under fast-rising transients.

It delivers 500 A_(pk) surge capability at 10×1000 µs waveform with 4.0 V on-state drop at 1 A, enabling robust energy diversion without thermal runaway. The device is rated for −40 °C to +150 °C operation and meets UL 1950, IEC 60950, and TIA-968-A safety standards.

Key Specifications

Pinout & Package

NP3500SBT3G uses the SMB (DO-214AA, Case 403C) surface-mount package: 4.06–4.57 mm length, 3.30–3.81 mm width, 1.90–2.41 mm height, with gull-wing leads. Thermal resistance is 90 °C/W (Junction-to-Ambient, FR4 3″×4.5″ board).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar thyristor surge protector applications.

Compared with NP3500SBT3G, both NP3500SAT3G and NP3500SCT3G share identical electrical, thermal, and mechanical specifications - they differ only in date/lot marking and internal traceability codes, making them functionally indistinguishable in all telecom surge protection designs.

Availability

NP3500SBT3G is available at Aetrix Electronics and suitable for DSL line cards, central office subscriber line interfaces, and customer premises equipment requiring stable component supply, long-lifecycle support, and GR-1089-CORE-certified surge protection.

Supply support for NP3500SBT3G 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient, high-reliability components for automotive, industrial, cloud power, and intelligent edge applications.

The NP Series thyristor surge protectors were developed specifically for telecom infrastructure protection, addressing stringent GR-1089-CORE, ITU-T K.20/K.21, and IEC 61000-4-5 requirements in central office, access network, and CPE systems.

FAQ

What is the maximum continuous operating voltage for NP3500SBT3G?

The NP3500SBT3G has a peak off-state voltage (V_DRM) of 320 V, meaning it can continuously block up to 320 V in either polarity without triggering. This rating applies at T_J = 25 °C and derates with junction temperature - at 125 °C, the effective V_DRM is approximately 280 V per onsemi's derating curves. Always verify system-level voltage margins under worst-case temperature and tolerance conditions when using NP3500SBT3G.

Does NP3500SBT3G require a gate trigger or external control circuit?

No, NP3500SBT3G is a passive, voltage-triggered thyristor device with no gate terminal. It operates autonomously: when voltage across MT1–MT2 exceeds 400 V (V_BO) in either direction, it latches into conduction until current drops below 150 mA (I_H). No biasing, timing, or drive circuitry is needed - the NP3500SBT3G functions as a self-acting crowbar, simplifying protection design in telecom line interfaces.

Can NP3500SBT3G be used in AC mains surge protection?

No, NP3500SBT3G is not rated or characterized for AC mains (120/230 VAC) applications. Its 320 V V_DRM is insufficient for continuous 230 VAC RMS (which peaks at ~325 V) with safety margin, and its surge waveforms (10×1000 µs, 2×10 µs) align with telecom GR-1089-CORE, not IEC 61643-11 for mains SPDs. Use dedicated AC-rated TSPDs or MOVs for mains protection - NP3500SBT3G is validated only for telecom low-voltage signal lines.

What is the thermal resistance and maximum power dissipation of NP3500SBT3G?

NP3500SBT3G has a junction-to-ambient thermal resistance (R_θJA) of 90 °C/W on a standard FR4 3″×4.5″ board with 2 oz copper. At 1 A clamping current and 4.0 V on-state drop, instantaneous power is 4 W - resulting in ~360 °C junction rise above ambient, which exceeds safe limits. Therefore, NP3500SBT3G is intended for short-duration surge events only; sustained conduction must be avoided via proper system current limiting to prevent thermal failure.

How does NP3500SBT3G compare to TVS diodes for telecom surge protection?

Unlike unidirectional or bidirectional TVS diodes, NP3500SBT3G provides true crowbar action: once triggered, it maintains low impedance (<1 Ω) until current falls below 150 mA, offering superior energy handling (500 A_(pk)) and lower clamping voltage stability under high-current surges. TVS devices exhibit higher dynamic impedance and may fail open under repeated stress. NP3500SBT3G is preferred where GR-1089-CORE Level 3 compliance and multi-surge endurance are mandatory - as confirmed in onsemi's qualification testing for NP3500SBT3G.