Texas Instruments LM25017SDE/NOPB

Overview

LM25017SDE/NOPB from Texas Instruments is a 48-V, 650-mA synchronous buck/Fly-Buck™ regulator with integrated high-side and low-side N-channel MOSFETs, constant on-time (COT) control, no loop compensation required, and adjustable switching frequency up to 1 MHz - used in isolated bias supplies and industrial power rails.

For engineers reviewing the LM25017SDE/NOPB datasheet, LM25017SDE/NOPB pinout, LM25017SDE/NOPB application, or LM25017SDE/NOPB equivalent, key selection criteria include input voltage range (7.5–48 V), FB reference accuracy (±2%, 1.225 V), thermal shutdown (165°C), UVLO programmability, and bootstrap gate drive architecture for high-side N-MOSFET operation.

Technical Context

The LM25017SDE/NOPB implements constant on-time (COT) control with VIN-inversely proportional on-time set by RON, enabling near-constant frequency across 7.5–48 V input and eliminating need for external loop compensation. Its intelligent peak current limit uses VIN- and VFB-dependent off-timer (144 ns minimum) for short-circuit protection without foldback.

It integrates a 7.6-V internal VCC regulator with 4.5-V UVLO, bootstrap capacitor charging via internal diode from VCC to BST, and dual-level UVLO (0.66 V shutdown, 1.225 V enable) with externally programmable threshold and hysteresis - supporting Fly-Buck™ isolation via transformer-coupled secondary output.

Key Specifications

Pinout & Package

LM25017SDE/NOPB is packaged in an 8-pin HSOP (DDA) with 4.89 mm × 3.90 mm body and exposed thermal pad soldered to RTN.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM25011MF/NOPB and LM5164QDDARQ1, the LM25017SDE/NOPB uniquely balances 48-V input rating, integrated Fly-Buck™-ready pinout (BST/SW), and precision 1.225-V FB reference - making it optimal for cost-sensitive, isolated bias rail designs where 650-mA output suffices.

Availability

LM25017SDE/NOPB is available at Aetrix Electronics and suitable for industrial equipment, smart power meters, and telecommunication systems requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for LM25017SDE/NOPB 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 leader designing analog, embedded processing, and power management ICs for industrial, automotive, and communications markets.

The LM25017SDE/NOPB belongs to TI's high-voltage DC-DC regulator product line, engineered specifically for efficient, compact, and isolated power conversion in space-constrained industrial and metering applications.

FAQ

What is the maximum input voltage supported by the LM25017SDE/NOPB?

The LM25017SDE/NOPB supports a maximum input voltage of 48 V, with absolute maximum rating of 53 V for VIN to RTN. Operation above 48 V violates recommended conditions and risks premature failure due to overstress on internal MOSFETs and VCC regulator. The device is optimized for industrial 24-V and telecom 48-V rails, and its constant on-time control maintains stable frequency across the full 7.5–48 V operating range.

Does the LM25017SDE/NOPB require external loop compensation components?

No, the LM25017SDE/NOPB does not require external loop compensation components. Its constant on-time (COT) control architecture eliminates the need for compensation networks by using an on-time inversely proportional to VIN and terminating off-time when FB falls below the 1.225-V reference. This simplifies design, improves transient response, and avoids stability issues associated with traditional voltage-mode or current-mode control - confirmed in Section 7.3.1 of the official datasheet.

Can the LM25017SDE/NOPB be used in Fly-Buck™ topology, and what pins are critical for that implementation?

Yes, the LM25017SDE/NOPB is explicitly designed for Fly-Buck™ operation. Critical pins include SW (switching node), BST (bootstrap capacitor connection), and RTN (ground reference). The SW node couples to the primary winding of an isolated transformer, while the secondary generates isolated output(s); BST ensures proper high-side gate drive during flyback action. TI's application notes confirm this topology is validated and supported - no secondary-side feedback or optocoupler is needed.

What is the purpose of the RON pin on the LM25017SDE/NOPB, and how is it configured?

The RON pin on the LM25017SDE/NOPB sets the constant on-time duration via an external resistor connected between RON and VIN. On-time is calculated as T_ON = (9×10⁻¹¹) × R_ON / V_IN, resulting in nearly constant frequency across input voltage variations. A 100-kΩ resistor yields ~250 ns at 48 V. Minimum on-time must exceed 100 ns for reliable operation - limiting max frequency at high VIN. This configuration replaces traditional frequency-setting resistors found in voltage-mode controllers.

How does the LM25017SDE/NOPB handle thermal overload conditions?

The LM25017SDE/NOPB incorporates a dedicated thermal shutdown circuit that triggers at 165°C junction temperature, disabling both the buck switch and internal VCC regulator. After shutdown, operation resumes only when junction temperature falls to ~145°C (20°C hysteresis). This protects against catastrophic failure during sustained overload or poor heatsinking. Thermal metrics (e.g., R_θJA = 41.1°C/W for HSOP-8) are specified in the datasheet to guide PCB layout and thermal design for the LM25017SDE/NOPB.