onsemi NP3500SBMCT3G

Overview

NP3500SBMCT3G from onsemi is a bidirectional ultra-low-capacitance thyristor surge protection device (TSPD) designed for telecom line protection in high-speed data circuits. It features ±320 V repetitive peak off-state voltage (V_DRM), ±400 V breakover voltage (V_BO), 23 pF nominal off-state capacitance at 1 MHz, 4 V on-state voltage at 2.2 A, and 150 mA holding current - enabling transparent operation and low-distortion clamping in xDSL and T1/E1 interfaces.

For engineers reviewing the NP3500SBMCT3G datasheet, pinout, applications, or equivalent options, key selection criteria include V_DRM margin above system operating voltage, V_BO alignment below protected circuit failure threshold, low Co for signal integrity, surge current capability per GR-1089-CORE Level C (500 A pk), and SMB package compatibility with telecom PCB layouts.

Technical Context

The NP3500SBMCT3G operates as a crowbar-type protector: it remains high-impedance (open-circuit) during normal operation (IDRM ≤ 5 µA at VDRM), then switches to low-impedance (short-circuit) when transient voltage exceeds ±400 V, shunting surge energy to ground. Its bidirectional symmetry enables protection of AC-coupled telecom lines without polarity concerns.

Thermal design relies on its SMB (DO-214AA) package with 90°C/W junction-to-ambient thermal resistance; electrical robustness includes 500 A non-repetitive peak impulse current (IPPS7, 10×1000 µs waveform) and ±500 A/µs critical di/dt rating - ensuring reliable triggering under fast-rising transients while avoiding false turn-on.

Key Specifications

Pinout & Package

NP3500SBMCT3G 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 spaced 2.26 mm apart. The device is bidirectional and symmetrical; both terminals serve identical roles.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NP3500SCMC and SLVU2.8-4, the NP3500SBMCT3G uniquely delivers telecom-grade bidirectional surge immunity (500 A, ±400 V) in the space-constrained SMB footprint - making it irreplaceable for high-density DSLAM and T1/E1 line card designs where both size and regulatory compliance are mandatory.

Availability

NP3500SBMCT3G is available at Aetrix Electronics and suitable for xDSL central office equipment, T1/E1 interface modules, and broadband access gateways requiring stable component supply, full traceability, and long-term lifecycle support.

Supply support for NP3500SBMCT3G 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 delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The NPMC Series - including NP3500SBMCT3G - was engineered specifically for telecom line protection, balancing ultra-low capacitance, precise breakover voltage, and high surge current to meet GR-1089-CORE, ITU-T K.20/K.21, and FCC Part 68 requirements.

FAQ

What is the maximum continuous operating voltage for NP3500SBMCT3G?

The NP3500SBMCT3G has a repetitive peak off-state voltage (V_DRM) of ±320 V, meaning it can safely withstand continuous AC+DC line voltages up to this level without triggering. This rating ensures compatibility with telecom systems featuring 48 V DC battery feed叠加150 V RMS ringing voltage (≈212 V peak), providing sufficient margin for normal operation while remaining below the ±400 V breakover threshold.

Does NP3500SBMCT3G require external bias or control circuitry to function?

No, the NP3500SBMCT3G is a passive crowbar device that operates autonomously - it requires no external power, bias, or control signals. Its behavior is defined solely by applied voltage: it remains high-impedance below ±400 V and switches to low-impedance conduction above that threshold. This self-contained operation makes NP3500SBMCT3G ideal for fail-safe telecom protection where reliability and simplicity are critical.

How does the 23 pF off-state capacitance of NP3500SBMCT3G impact DSL signal integrity?

The 23 pF off-state capacitance of NP3500SBMCT3G introduces negligible insertion loss (<0.5 dB) and group delay variation across the full ADSL2+ band (up to 2.2 MHz), preserving bit error rate (BER) performance. Unlike higher-capacitance protectors, this value avoids resonant peaking near line-card filter cutoff frequencies and maintains impedance matching on 100 Ω twisted-pair lines - a key reason NP3500SBMCT3G is specified for central office DSLAM deployments.

Can NP3500SBMCT3G be used in unidirectional applications?

Yes, the NP3500SBMCT3G is inherently bidirectional but functions correctly in unidirectional configurations - for example, protecting a single-ended DC-powered line where one terminal connects to the signal and the other to ground. Its symmetrical structure means polarity assignment is arbitrary; however, its ±400 V V_BO and ±320 V V_DRM ratings apply equally in both directions, so no derating is needed for unidirectional use cases.

What is the thermal limitation of NP3500SBMCT3G during repeated surge events?

The NP3500SBMCT3G has a junction-to-ambient thermal resistance (R_θJA) of 90°C/W on a standard FR4 PCB (3″×4.5″, 2 oz copper). While rated for non-repetitive 500 A surges, repeated events require ≥1 second cooling intervals to prevent cumulative heating beyond the +150°C max junction temperature. For applications with frequent surges, derating curves in the datasheet (Figure 2) must be consulted - NP3500SBMCT3G's thermal design assumes single-event duty unless heatsinking or airflow is added.