Texas Instruments LM2597MX-12

Overview

LM2597MX-12 from Texas Instruments is a monolithic 150-kHz nonsynchronous step-down (buck) DC-DC converter delivering up to 0.5 A output current with fixed 12-V output, ±4% regulation over line/load/temperature, 4.5–40 V input range, and integrated soft-start/shutdown/error flag functions - used in industrial power supplies and embedded system point-of-load conversion.

For engineers reviewing the LM2597MX-12 datasheet, LM2597MX-12 pinout, LM2597MX-12 application, or LM2597MX-12 equivalent, key selection criteria include its 12-V fixed output accuracy, 85-μA standby current, SOIC-8 package compatibility, and bias supply (VBS) pin for efficiency optimization at high VIN/low VOUT conditions.

Technical Context

The LM2597MX-12 implements a fixed-frequency (150 kHz ±15%) current-mode control architecture with internal compensation, enabling stable operation using standard off-the-shelf inductors and minimal external components. Its nonsynchronous buck topology uses an internal NPN switch with 1.1-V typical saturation voltage at 0.5-A load.

It integrates supervisory features including an open-collector error flag activated when output drops >5%, a programmable delay pin for power-up sequencing, and a bias supply (VBS) pin that powers internal circuitry from VOUT instead of VIN - improving efficiency by reducing quiescent current draw from high-input rails.

Key Specifications

Pinout & Package

LM2597MX-12 is housed in an 8-pin SOIC (D) package measuring 4.90 mm × 3.91 mm, optimized for surface-mount assembly and thermal performance on standard FR-4 PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2596-12 and TPS5430-12, the LM2597MX-12 uniquely balances wide 4.5–40-V input support, SOIC-8 surface-mount compatibility, integrated error flag/delay, and VBS-driven efficiency gains - making it optimal for industrial 12-V conversion where reliability, simplicity, and input flexibility are prioritized over raw current or peak efficiency.

Availability

LM2597MX-12 is available at Aetrix Electronics and suitable for industrial power supplies, embedded system point-of-load conversion, positive-to-negative converters, and preregulator applications requiring stable component supply across long-lifecycle programs.

Supply support for LM2597MX-12 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 LM2597MX-12 belongs to TI's SIMPLE SWITCHER® family - designed specifically for robust, easy-to-implement DC-DC conversion in industrial, automotive, and communications equipment where minimal external components and proven reliability are critical.

FAQ

What is the maximum input voltage rating for the LM2597MX-12?

The LM2597MX-12 has a maximum input voltage rating of 40 V, with recommended operating range from 4.5 V to 40 V. Exceeding 40 V risks permanent damage per Absolute Maximum Ratings. The HV variant (LM2597HV-12) supports up to 60 V, but LM2597MX-12 is strictly rated for 40 V - confirmed in Section 7.1 and 7.3 of the SNVS119D datasheet.

Does the LM2597MX-12 require external feedback resistors to set its output voltage?

No, the LM2597MX-12 is a fixed-output version with internal 12-V feedback reference. Pin 4 (Feedback) is internally connected and must be left unconnected - unlike the adjustable LM2597ADJ, which requires external resistors. This simplifies layout and eliminates resistor tolerance errors affecting output accuracy.

How does the Bias Supply (VBS) pin improve efficiency in the LM2597MX-12?

The VBS pin allows the LM2597MX-12's internal circuitry to be powered from the regulated 12-V output instead of the higher VIN rail. At VIN = 36 V, this reduces operating quiescent current by ~80%, directly lowering power dissipation and junction temperature - especially beneficial in high-input, low-output current scenarios per Figure 19 and Section 8.3.1.

Can the LM2597MX-12 be used in an inverting (positive-to-negative) configuration?

Yes, the LM2597MX-12 supports inverting buck-boost topologies per Figure 24 in the datasheet. It generates –12 V from +24 V input using external diode, inductor, and capacitor. Critical constraints include limiting |VIN| + |VOUT| ≤ 40 V and using soft-start to manage high startup currents - verified in Section 8.3.3.

What thermal management is required for continuous 0.5-A operation of the LM2597MX-12?

With its SOIC-8 package θJA of 95 °C/W, the LM2597MX-12 requires only a 1-in² copper pour on the PCB for heatsinking at full 0.5-A load and 25°C ambient - no external heatsink needed. Thermal performance improves with additional copper area, as noted in Section 7.4 and Layout Guidelines (Section 11).