Texas Instruments SN65240PW

Overview

SN65240PW from Texas Instruments is a quadruple unidirectional transient voltage suppressor (TVS) designed for ESD protection of USB full-speed and low-speed ports. It features 6.5-V minimum breakdown voltage, 35-pF typical input capacitance, ≤1-µA leakage at 6 V, ±15-kV HBM ESD rating, and operates from –40°C to 85°C. It protects D+ and D– data lines in USB transceivers against electrical noise transients.

For engineers reviewing the SN65240PW datasheet, SN65240PW pinout, SN65240PW application, or SN65240PW equivalent, this page delivers verified technical context, package-specific pin functions, real-world USB port protection use cases, and validated alternative options for robust I/O hardening design.

Technical Context

The SN65240PW integrates four independent unidirectional TVS diodes in a single TSSOP-8 package, each with Zener-triggered transistor-based clamping for positive transients and forward-biased diode conduction for negative transients. Its structure enables fast response to ESD events while maintaining high-impedance operation during normal USB signaling.

It operates without external power supply, relying solely on transient voltage thresholds (6.5 V min breakdown) to activate clamping. The device requires direct, low-inductance grounding via all four GND pins to ensure effective shunting of surge current-critical for preserving signal integrity at 12 Mbps USB full-speed data rates.

Key Specifications

Pinout & Package

TSSOP-8 (PW) package: 3.00 mm × 4.40 mm body, 1.2 mm max height, lead pitch 0.65 mm, RoHS-compliant NiPdAu finish, MSL Level-1 (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar transient suppression applications.

Compared with SN65240PW, SN65240PWR offers identical performance with assured supply continuity, while SN75240PW trades industrial temp range for lower cost in benign environments - making SN65240PW the optimal choice for ruggedized USB designs requiring –40°C to 85°C operation.

Availability

SN65240PW is available at Aetrix Electronics and suitable for USB full-speed host ports, industrial peripheral interfaces, and embedded hub controller designs requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN65240PW 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

Texas Instruments is a global semiconductor company delivering analog and embedded processing solutions, with leadership in precision analog, power management, and interface technologies.

The SN65240PW belongs to TI's USB transient suppressor product line, engineered specifically to harden USB 1.1 full-speed and low-speed interfaces against ESD and electrical noise in industrial, computing, and medical applications.

FAQ

What is the primary function of the SN65240PW in a USB interface?

The SN65240PW serves as a quadruple unidirectional transient voltage suppressor that protects USB D+ and D– data lines from ESD and electrical noise transients. It clamps voltage spikes above 6.5 V to prevent damage to downstream USB transceivers or ASICs. Its 35-pF capacitance and ≤1-µA leakage ensure compatibility with full-speed (12 Mbps) USB signaling without signal degradation. The SN65240PW achieves this without requiring external power, operating purely on voltage-threshold activation.

Does the SN65240PW support USB 2.0 High-Speed (480 Mbps) operation?

No, the SN65240PW does not support USB 2.0 High-Speed operation. Its 35-pF typical input capacitance is too high for 480-Mbps signaling, which demands sub-2-pF capacitance to maintain signal integrity and eye diagram compliance. The datasheet explicitly states the SN65240PW is intended for USB low-speed (1.5 Mbps) and full-speed (12 Mbps) applications only. For USB 2.0 HS, designers must select lower-capacitance TVS devices such as the TPD2EUSB30 or similar high-bandwidth suppressors.

How many ground connections does the SN65240PW require, and why are they critical?

The SN65240PW has four dedicated GND pins (Pins 1, 3, 5, and 7) in its TSSOP-8 package, and all must be connected to a low-inductance ground plane. This multi-ground architecture minimizes parasitic inductance in the surge-current path, enabling effective shunting of high-di/dt ESD transients (up to ±9 A peak). Failure to connect all GND pins degrades clamping speed and increases voltage overshoot, risking USB transceiver damage. Board layout guidelines mandate direct vias to a solid ground plane - not daisy-chained traces - to preserve the SN65240PW's ±15-kV HBM rating.

What is the significance of the 6.5-V minimum breakdown voltage for the SN65240PW?

The 6.5-V minimum breakdown voltage ensures the SN65240PW remains non-conductive during normal USB operation (where VBUS = 4.75–5.25 V and data swings are ±0.3 V), preventing signal loading or DC leakage. It activates clamping only when transients exceed this threshold - safely above the USB supply rail but well below the 7–10-V damage threshold of typical 3.3-V/5-V CMOS transceivers. This margin allows the SN65240PW to absorb energy from ±15-kV HBM strikes without interfering with legitimate signaling, making it ideal for protecting sensitive USB PHY layers.

Is the SN65240PW compatible with both 3-V and 5-V USB transceivers?

Yes, the SN65240PW is explicitly designed to protect submicron 3-V and 5-V USB transceivers. Its 6.5-V minimum breakdown voltage provides sufficient headroom above 3.3-V logic rails while remaining compatible with 5-V tolerant USB PHYs. The device's low leakage (≤1 µA at 6 V) avoids pulling down data line voltages in either voltage domain, and its unidirectional architecture ensures correct polarity alignment with USB differential signaling. TI's datasheet confirms suitability for both 3-V and 5-V circuits in the "Features" and "Description" sections of the SN65240PW documentation.