Texas Instruments LM25575MHX

Overview

LM25575MHX from Texas Instruments is a 42V, 1.5A synchronous step-down DC/DC switching regulator with integrated 330mΩ N-channel MOSFET, emulated current-mode control, and adjustable 50kHz–1MHz switching frequency. It delivers regulated output down to 1.225V with 1.5% feedback reference accuracy and supports industrial power conversion from 6V–42V input rails.

For engineers reviewing the LM25575MHX datasheet, LM25575MHX pinout, LM25575MHX application, or LM25575MHX equivalent, key selection criteria include its HTSSOP-16EP package thermal performance (R_θJC(bot) = 1.5°C/W), cycle-by-cycle current limit (2.1A typ), soft-start programmability, and SYNC pin for multi-regulator EMI reduction - all critical for robust high-voltage buck design.

Technical Context

The LM25575MHX implements emulated current-mode control using a reconstructed ramp signal derived from VIN–VOUT and a diode-current sample-and-hold circuit, eliminating leading-edge spikes and enabling stable operation at low duty cycles. Its dual-mode VCC regulator maintains 7V bias up to 42V input while limiting internal dissipation.

Functional integration includes a dedicated IS pin for diode current sensing, BST/SW bootstrap charging with forced 500ns off-time for capacitor recharge, and RT-resistor programmable oscillator with external synchronization capability via open-drain SYNC pin - supporting coordinated multi-rail power sequencing.

Key Specifications

Pinout & Package

LM25575MHX is housed in a thermally enhanced HTSSOP-16EP (PWP) package measuring 5mm × 4.4mm with an exposed die attach pad soldered to PCB ground for optimal heat transfer (R_θJC(bot) = 1.5°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM25575MHX, LM25574MHX offers identical interface and layout compatibility at half the current rating, while LM5164HKEVM targets fundamentally different high-voltage use cases with no mechanical or electrical interchangeability.

Availability

LM25575MHX is available at Aetrix Electronics and suitable for industrial automation, telecom infrastructure, and automotive body electronics requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LM25575MHX 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 specializing in analog, embedded processing, and power management technologies with decades of high-reliability power IC design expertise.

The LM25575 product line delivers easy-to-use, high-voltage buck regulators targeting industrial, telecom, and automotive power systems where input transients, thermal constraints, and minimal external components are critical design factors.

FAQ

What is the maximum input voltage rating for the LM25575MHX?

The LM25575MHX has an absolute maximum input voltage rating of 45V, with recommended operation from 6V to 42V. Exceeding 45V risks permanent damage. The device's internal VCC regulator automatically transitions from direct VIN tracking below 9V to regulated 7V output above 9V, enabling robust operation across this full range without external LDOs or charge pumps.

How does the LM25575MHX implement current sensing without a sense resistor?

The LM25575MHX uses an integrated diode-current sensing scheme: the IS pin connects to the Schottky diode anode, and an internal 83mΩ sense resistor between IS and PGND generates a voltage proportional to re-circulating current. This voltage is sampled and held just before switch turn-on to provide the DC level for the emulated current ramp - eliminating external sense resistors and associated power loss.

Can the LM25575MHX be synchronized to an external clock source?

Yes, the LM25575MHX supports external synchronization via its SYNC pin, which accepts open-drain clock inputs ≥550kHz. When multiple LM25575MHX devices share a SYNC net, the highest-frequency unit acts as master. This capability enables deterministic phase alignment across power rails to reduce EMI peak amplitude and simplify compliance testing for the LM25575MHX-based system.

What thermal performance can be expected from the LM25575MHX in a typical 2-layer PCB layout?

In a standard 2-layer PCB with the exposed pad fully soldered to a 10cm² internal ground plane, the LM25575MHX achieves R_θJA ≈ 38.4°C/W. At 1.5A output and 24V input, typical power dissipation is ~1.2W, resulting in ~46°C junction rise above ambient - well within the 125°C max operating temperature. For higher ambient or sealed enclosures, adding thermal vias under the EP improves R_θJB to 15.6°C/W.

Does the LM25575MHX require external compensation components?

Yes, the LM25575MHX requires external compensation components connected between COMP and FB pins - typically a Type-II network (series RC shunted by capacitor) - to stabilize the control loop. The error amplifier's 70dB DC gain and 3MHz unity-gain bandwidth necessitate careful pole-zero placement based on output filter values; TI's WEBENCH® Power Designer provides validated designs for common configurations using the LM25575MHX.