Texas Instruments LM3525MX-H

Overview

LM3525MX-H from Texas Instruments (formerly National Semiconductor) is a single-port, high-side P-channel USB power switch with active-high enable, providing over-current protection, thermal shutdown, and undervoltage lockout for USB root and self-powered hubs. It operates from 2.7V to 5.5V, delivers ≥500 mA continuous load current, limits short-circuit current to 1.0 A typical, and features ≤120 mΩ R_ON at 5 V - enabling robust inrush current limiting in notebook PC and monitor hub applications.

For engineers reviewing the LM3525MX-H datasheet, LM3525MX-H pinout, LM3525MX-H application, or LM3525MX-H equivalent, key selection criteria include its SO-8 package compatibility, 1 ms fault flag delay for hot-plug immunity, active-high enable logic, 1 µA standby current, and UL recognition (REF #205202) for safety-critical USB power delivery designs.

Technical Context

The LM3525MX-H implements a thermally protected, current-limited high-side P-MOSFET switch with integrated UVLO (1.9 V turn-on / 1.8 V turn-off), 135 °C thermal shutdown with 10 °C hysteresis, and open-drain active-low FLG output that asserts on over-current, UVLO, or thermal fault. Its internal soft-start limits inrush to 1.0 A during turn-on.

It supports USB 1.1 and USB 2.0 compliance via precise current-limit threshold (2.25–3.2 A), 1 ms transient over-current delay to ignore hot-plug surges, and low R_ON to minimize voltage drop across IN–OUT under full 500 mA load - critical for maintaining V_BUS regulation in space-constrained hub PCB layouts.

Key Specifications

Pinout & Package

LM3525MX-H is housed in an SO-8 package (NS Package Number M08A), with pins 6 and 8 internally tied as a single output terminal to reduce trace resistance and improve current handling.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar USB power switch applications.

Compared with TUSB2036IRHBR and TPS2051BDBVR, LM3525MX-H uniquely combines UL recognition, 1 ms fault delay for USB hot-plug reliability, and P-MOSFET architecture optimized for ganged self-powered hub use - making it the preferred choice where safety certification and transient immunity are mandatory.

Availability

LM3525MX-H is available at Aetrix Electronics and suitable for USB root hubs, monitor hubs, and high-power peripheral inrush limiting requiring stable component supply, long-term lifecycle support, and consistent SO-8 packaging.

Supply support for LM3525MX-H 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 acquired National Semiconductor in 2011 and maintains full technical and supply chain continuity for legacy analog products including the LM3525 family.

The LM3525MX-H belongs to TI's legacy USB power management portfolio, designed specifically for reliable, certified, single-port V_BUS switching in desktop, notebook, and self-powered hub applications.

FAQ

What is the enable logic polarity of the LM3525MX-H?

The LM3525MX-H uses active-high enable logic: the internal P-MOSFET switch turns ON when the EN pin voltage is ≥2.4 V, and turns OFF when EN ≤0.8 V. This matches standard 3.3 V and 5 V microcontroller GPIO outputs without requiring inverters. The LM3525MX-H datasheet explicitly defines this behavior in the DC Electrical Characteristics table under VIH/VIL parameters, distinguishing it from the LM3525MX-L variant which uses active-low enable.

Does the LM3525MX-H require external components for basic operation?

No, the LM3525MX-H operates autonomously with only input and output capacitors required per USB specification - a 33 µF input tantalum capacitor and ≥120 µF output bulk capacitor. It integrates soft-start, current limiting, thermal shutdown, UVLO, and 1 ms fault flag delay internally. No external resistors, capacitors, or diodes are needed for core protection functions, simplifying design and reducing bill-of-materials count.

What is the maximum continuous load current supported by the LM3525MX-H?

The LM3525MX-H guarantees a minimum continuous output current of 500 mA across its full operating temperature range (−40 °C to +85 °C ambient). This is specified in the Applications section and confirmed in the DC Electrical Characteristics table under I_OUT. At higher temperatures or with poor PCB thermal design, derating may apply - but under standard SO-8 layout with adequate copper pour, 500 mA is reliably sustainable without thermal shutdown.

How does the 1 ms fault flag delay in the LM3525MX-H improve USB system reliability?

The 1 ms fault flag delay in the LM3525MX-H prevents false over-current assertions during hot-plug events, when downstream peripheral bulk capacitance causes brief inrush currents exceeding the 2.25–3.2 A current limit threshold. By ignoring transients shorter than 1 ms, the LM3525MX-H allows safe plug-in without forcing the host controller into error recovery - a critical feature validated in USB compliance testing and explicitly called out in the Functional Description and Application Information sections.

Is the LM3525MX-H UL recognized, and what does that mean for end-equipment certification?

Yes, the LM3525MX-H is UL Recognized as a Component under File E205202. This means the device itself has been evaluated by UL for safety - including dielectric strength, flammability, and fault withstand - and can be used in end products without retesting those specific failure modes. For designers, this reduces time and cost for final product safety certification (e.g., UL 62368-1), especially in USB-powered monitors, docks, and computing peripherals where primary-side power switching is involved.