Texas Instruments LM5575MHX

Overview

LM5575MHX from Texas Instruments is a 75V input, 1.5A synchronous step-down switching regulator with integrated 330mΩ N-channel MOSFET, emulated current-mode control, and adjustable 50–500kHz switching frequency. It delivers regulated DC output down to 1.225V and supports automotive and industrial power conversion in telecom bus, battery-powered equipment, and distributed power systems.

For engineers reviewing the LM5575MHX datasheet, LM5575MHX pinout, LM5575MHX application, or LM5575MHX equivalent, key selection considerations include its 75V absolute max input rating, HTSSOP-16EP thermal performance (θ_JA = 50°C/W), cycle-by-cycle current limit at 2.1A typ, and SYNC-capable multi-device synchronization for EMI-sensitive designs.

Technical Context

The LM5575MHX implements emulated current-mode control using a reconstructed ramp signal derived from VIN–VOUT and an internal diode-current sample-and-hold circuit - eliminating leading-edge spikes and enabling stable operation at very low duty cycles. Its dual-mode VCC regulator maintains ~7V bias supply above 9V input while tracking VIN below that threshold.

It integrates a 75V/330mΩ buck switch, programmable oscillator via RT resistor, soft-start via SS capacitor, and protection features including thermal shutdown (165°C), cycle-by-cycle current limiting, and remote shutdown via SD pin with 0.7V/1.225V thresholds. The SYNC pin supports master-slave synchronization across up to five devices without external logic.

Key Specifications

Pinout & Package

LM5575MHX is housed in a thermally enhanced 16-pin HTSSOP package with exposed pad (EP) for PCB ground connection to improve thermal dissipation (θ_JC = 14°C/W). The exposed pad must be soldered to a copper pour for reliable operation at full load.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down regulator applications.

Compared with LM5575MHX, LM5576MHX offers higher current capacity in identical packaging, while LM25011MF/NOPB provides a lower-cost, lower-voltage alternative lacking synchronization and advanced startup features - making LM5575MHX optimal for 75V, thermally constrained, or multi-rail synchronized systems.

Availability

LM5575MHX is available at Aetrix Electronics and suitable for telecom infrastructure, automotive body electronics, industrial PLCs, and distributed battery backup systems requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant performance.

Supply support for LM5575MHX 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 over 90 years of innovation in high-reliability electronics.

The LM5575MHX belongs to TI's SIMPLE SWITCHER® portfolio - engineered for rugged, easy-to-use DC/DC conversion in harsh environments where wide input range, thermal resilience, and minimal external components are critical.

FAQ

What is the maximum input voltage rating for the LM5575MHX?

The LM5575MHX has an absolute maximum input voltage rating of 76V, with recommended continuous operation from 6V to 75V. This rating enables direct connection to 48V telecom buses, 24V/36V industrial systems, and 12V automotive batteries with cold-crank headroom. Exceeding 76V risks permanent damage, especially during transient events - proper input clamping and layout are essential.

Does the LM5575MHX require an external bootstrap capacitor, and what value is recommended?

Yes, the LM5575MHX requires an external ceramic bootstrap capacitor between BST and SW pins. Texas Instruments recommends a 0.022µF X7R or C0G capacitor placed with minimal trace length. This capacitor supplies gate drive voltage for the internal high-side N-channel MOSFET during switching. Using the specified value ensures reliable bootstrapping across the full 50–500kHz frequency range and input voltage conditions.

How does the LM5575MHX implement current sensing without a sense resistor?

The LM5575MHX uses an internal diode-current sample-and-hold circuit connected to the IS pin, combined with an emulated ramp generator referenced to (VIN – VOUT). This reconstructs the inductor current waveform without a discrete sense resistor - reducing component count, board space, and power loss. The IS pin measures recirculating diode current near turn-off, while the RAMP pin generates a proportional voltage slope via external capacitor and internal current source.

Can multiple LM5575MHX ICs be synchronized, and how is this achieved?

Yes, multiple LM5575MHX ICs can be synchronized using the SYNC pin. Connecting SYNC pins together allows automatic master-slave operation - the device with the highest programmed frequency pulls the shared line low first and forces others to align. Alternatively, an external clock (with open-drain output and >15ns pulse width) can drive the SYNC pin. This reduces beat frequencies and EMI peaks in multi-rail systems.

What thermal management practices are recommended for the LM5575MHX at full 1.5A load?

For sustained 1.5A operation, the LM5575MHX requires the exposed pad (EP) to be soldered to a minimum 200mm² copper pour connected to internal/external ground planes. Thermal vias (≥6×0.3mm) should connect the pad to inner-layer ground. With this layout, θ_JA drops from 50°C/W to ~35°C/W, allowing operation up to 75°C ambient. Derating is advised above 125°C junction temperature - thermal shutdown activates at 165°C.