Texas Instruments LM5008SDX

Overview

LM5008SDX from Texas Instruments is a 95-V, 350-mA constant on-time (COT) buck switching regulator with integrated 100-V N-channel MOSFET, internal 7-V VCC series regulator, and intelligent current limit protection. It operates from 9.5 V to 95 V input, delivers regulated output via external resistor divider (FB = 2.5 V reference), and supports remote shutdown via RON/SD pin. Used in high-voltage post-regulation for telecom and industrial power supplies.

For engineers reviewing the LM5008SDX datasheet, LM5008SDX pinout, LM5008SDX application, or LM5008SDX equivalent, key selection criteria include input voltage range (9.5–95 V), integrated switch R_DS(on) (1.15 Ω typ), minimum off-time (300 ns), thermal shutdown (165 °C), and COT control requiring no loop compensation.

Technical Context

The LM5008SDX uses a hysteretic constant-on-time control architecture where on-time varies inversely with VIN (T_ON = 1.25×10⁻¹⁰ × R_ON/V_IN), enabling near-constant operating frequency across line and load variations. It operates in discontinuous conduction mode (DCM) at light loads and continuous conduction mode (CCM) at heavier loads, with automatic mode transition.

Regulation relies on a 2.5-V internal reference compared against FB voltage; overvoltage protection triggers at 2.875 V. Current limiting employs an off-timer whose duration depends on both R_CL and FB voltage (T_OFF = 10⁻⁵ / (0.285 + (FB / 6.35×10⁻⁶ × R_CL))), providing adaptive short-circuit response from 2.56 µs to 35 µs.

Key Specifications

Pinout & Package

LM5008SDX is packaged in an 8-pin WSON (NGU) package with 4.00 mm × 4.00 mm body size and exposed thermal pad (EP) connected to ground for enhanced thermal performance (R_θJA = 42 °C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar buck regulator applications.

Compared with LM5008SDX, LM5164PWPR offers higher current and wider input range but increases design complexity with external FET and compensation, while MAX17504ATP+ provides higher frequency and better light-load efficiency below 60 V but cannot operate at 95 V - making LM5008SDX uniquely suited for high-input-voltage, low-component-count buck regulation.

Availability

LM5008SDX is available at Aetrix Electronics and suitable for telecom power conversion, automotive 48-V systems, and industrial sensor power supplies requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LM5008SDX 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 headquartered in Dallas, Texas, specializing in analog, embedded processing, and power management technologies with broad industrial, automotive, and communications market reach.

The LM5008 product line delivers high-voltage, integrated buck regulators optimized for simplicity and reliability in harsh-input environments - designed specifically for applications where input voltage exceeds 40 V and board space is constrained.

FAQ

What is the maximum input voltage rating for the LM5008SDX?

The LM5008SDX has an absolute maximum input voltage rating of 100 V and a recommended operating range of 9.5 V to 95 V. This allows it to safely handle transient surges common in telecom and industrial 48-V systems while maintaining continuous operation up to 95 V DC. Exceeding 95 V during normal operation may reduce reliability or trigger overvoltage protection.

Does the LM5008SDX require external compensation components?

No, the LM5008SDX does not require external compensation components. Its constant-on-time (COT) hysteretic control architecture eliminates the need for loop compensation networks, reducing bill-of-materials count and simplifying design. Stability is inherently maintained across line and load variations due to the fixed on-time and adaptive off-time behavior.

How does the LM5008SDX implement current limiting and short-circuit protection?

The LM5008SDX implements intelligent current limiting using an off-timer whose duration depends on both the R_CL resistor and FB voltage. At 0 V FB (e.g., output short), off-time is preset to 35 µs; at higher FB (e.g., moderate overload), off-time reduces to as low as 2.56 µs. This minimizes foldback and improves recovery speed while ensuring safe operation at 95 V input.

Can the LM5008SDX be used with an external bias supply instead of the internal VCC regulator?

Yes, the LM5008SDX supports external biasing of the VCC pin. Applying 8–14 V to VCC disables the internal 7-V series regulator, reducing power dissipation in high-input-voltage applications. The internal regulator shuts down automatically when VCC exceeds ~7 V, and gate drive remains fully functional as long as VCC stays within its 14-V absolute maximum rating.

What package type is used for the LM5008SDX and how does it impact thermal performance?

The LM5008SDX uses the 8-pin WSON (NGU) package with a 4.00 mm × 4.00 mm body and exposed thermal pad. This package achieves a junction-to-ambient thermal resistance (R_θJA) of 42 °C/W - significantly lower than the VSSOP variant (139.7 °C/W) - enabling higher power density and reliable operation in compact, thermally constrained layouts when the EP is soldered to a ground plane.