Texas Instruments LM5005MHX

Overview

LM5005MHX from Texas Instruments is a high-voltage, current-mode synchronous buck controller IC integrating a 75V/160mΩ N-channel MOSFET, delivering up to 2.5A output current across 7V–75V input range with adjustable output down to 1.225V; used in telecom power supplies and industrial DC-DC conversion where wide VIN and fast transient response are required.

For engineers reviewing the LM5005MHX datasheet, LM5005MHX pinout, LM5005MHX application, or LM5005MHX equivalent, key selection criteria include its emulated peak current-mode control architecture, 80ns minimum on-time, resistor-programmable 50–500kHz switching frequency, EN55022/CISPR 22 EMI compliance, and thermal shutdown with hysteresis - all critical for high-reliability, high-input-voltage point-of-load designs.

Technical Context

The LM5005MHX implements emulated peak current-mode control using a sample-and-hold DC level derived from freewheeling diode current (via IS pins) and an external RAMP capacitor-driven voltage-controlled current source that scales with (VIN − VOUT); this eliminates leading-edge spikes and enables stable operation at small duty cycles in high-VIN applications.

Its dual-mode VCC regulator delivers ~7V regulated bias above 9V VIN and tracks VIN below 9V, supporting startup from 7V while limiting internal dissipation; oscillator synchronization via the SYNC pin allows deterministic multi-phase operation or external clock locking without requiring additional timing components.

Key Specifications

Pinout & Package

LM5005MHX is housed in a thermally enhanced 20-pin HTSSOP (PWP) package with exposed pad soldered to PCB ground for low junction-to-board thermal resistance (15.5°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM5005MHX, LM5164MHX supports higher input voltage but cannot deliver 2.5A, while TPS54260DGQR matches output current but lacks critical synchronization and bootstrap-assist features needed for high-density, multi-phase, or low-light-load industrial designs.

Availability

LM5005MHX is available at Aetrix Electronics and suitable for telecommunications infrastructure, factory automation and control, and high-efficiency point-of-load regulators requiring stable component supply across extended temperature and wide-input-voltage conditions.

Supply support for LM5005MHX 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 expertise in high-reliability power conversion ICs.

The LM5005MHX belongs to TI's high-voltage DC-DC buck regulator product line, designed specifically for industrial, telecom, and automotive applications demanding robust operation across 7V–75V input ranges with minimal external components.

FAQ

What is the maximum input voltage rating for the LM5005MHX?

The LM5005MHX has an absolute maximum input voltage rating of 76V across VIN pins, with recommended operating range from 7V to 75V. Exceeding 76V risks permanent damage. The device incorporates internal VCC UVLO and gate driver protection to prevent latch-up during overvoltage transients, but external clamping or filtering remains essential for sustained reliability in noisy 75V bus environments. Always verify input ripple and ringing stay within absolute max limits using oscilloscope measurements at the VIN and PGND pins.

How does the LM5005MHX achieve stable operation at very small duty cycles?

The LM5005MHX achieves stable small-duty-cycle operation through its emulated peak current-mode control architecture, which eliminates leading-edge noise and propagation delays inherent in direct current sensing. Its 80ns minimum controllable PWM on-time, combined with a programmable RAMP capacitor that scales with input-output differential, enables reliable regulation even at extreme VIN/VOUT ratios like 75V→3.3V. This design avoids pulse-skipping and subharmonic oscillation without requiring external slope compensation.

Can the LM5005MHX be synchronized to an external clock signal?

Yes, the LM5005MHX supports external clock synchronization via its bidirectional SYNC pin. When driven by an external clock with frequency higher than the free-running oscillator (e.g., >550kHz for RT=11kΩ), the internal oscillator locks to the external edge. The SYNC pin features 11kΩ source impedance and 110Ω sink impedance, requiring an open-drain interface with appropriate pullup. This capability enables deterministic interleaving in multi-rail systems and EMI reduction through clock dithering or fixed-frequency alignment.

What thermal management considerations apply to the LM5005MHX in 2.5A operation?

At full 2.5A output, the LM5005MHX requires careful thermal design due to its 15.5°C/W junction-to-board thermal resistance. The exposed pad (EP) must be soldered to a minimum 400mm² copper area connected to inner-layer ground planes via ≥6 thermal vias. Ambient temperature must remain ≤85°C to keep junction temperature below 125°C. Derating is necessary above 70°C ambient; efficiency curves show ~85% at 48V→5V/2.5A, implying ~1.9W dissipation requiring ≥20°C rise margin.

Does the LM5005MHX support startup into a prebiased output?

Yes, the LM5005MHX provides monotonic start-up into prebiased outputs via its controlled soft-start circuitry. During startup, the SS pin voltage ramps linearly using an internal 10µA current source and external capacitor, forcing the error amplifier reference to rise gradually regardless of initial output voltage. This prevents reverse current flow through the freewheeling diode and avoids output voltage overshoot or instability - a critical feature for hot-swap and redundant power supply applications where downstream rails may already be energized.