Texas Instruments LM2597N-12/NOPB

Overview

LM2597N-12/NOPB from Texas Instruments is a monolithic 150-kHz nonsynchronous step-down (buck) DC-DC converter delivering up to 0.5 A at a fixed 12 V output, with ±4% output voltage tolerance over line and load, 4.5–40 V input range, and integrated shutdown/soft-start and error flag functions-used in industrial power supplies and embedded system point-of-load regulation.

For engineers reviewing the LM2597N-12/NOPB datasheet, LM2597N-12/NOPB pinout, LM2597N-12/NOPB application, or LM2597N-12/NOPB equivalent, key selection criteria include its fixed 12 V output, PDIP-8 package compatibility, 85 μA standby current, bias supply (VBS) pin for efficiency optimization at high VIN/low VOUT, and thermal shutdown protection.

Technical Context

The LM2597N-12/NOPB implements a fixed-frequency (150 kHz) current-mode control architecture with internal compensation, enabling stable operation with standard off-the-shelf inductors and minimal external components. Its nonsynchronous design uses an internal NPN switch and requires an external catch diode.

It integrates supervisory features including an open-collector error flag that asserts low when output drops >5% below nominal, a delay pin for programmable flag assertion timing, and a bias supply (VBS) pin that powers internal circuitry from VOUT-improving efficiency by reducing VIN current draw during light loads or high input voltages.

Key Specifications

Pinout & Package

LM2597N-12/NOPB is supplied in an 8-pin plastic dual in-line package (PDIP), body size 9.81 mm × 6.35 mm, with through-hole mounting and industry-standard lead pitch (0.1 inch). Thermal resistance θ_JA = 150 °C/W with standard 1-inch² copper pad.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2596-12 and LM2678-12, the LM2597N-12/NOPB uniquely balances moderate 0.5 A output, PDIP-8 through-hole compatibility, ultra-low 85 μA standby, and integrated sequencing features (soft-start, delay-timed error flag, VBS)-making it optimal for legacy industrial designs requiring reliability, serviceability, and precise power-good timing.

Availability

LM2597N-12/NOPB is available at Aetrix Electronics and suitable for industrial sensor power supplies, embedded system preregulators, on-card buck converters, and positive-to-negative inverter circuits requiring stable component supply, long-term obsolescence management, and through-hole assembly compatibility.

Supply support for LM2597N-12/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 company headquartered in Dallas, Texas, designing and manufacturing analog, embedded processing, and logic ICs for industrial, automotive, and communications markets.

The LM2597 series belongs to TI's SIMPLE SWITCHER® power converter family-engineered for ease of use in cost-sensitive, medium-power DC-DC applications where minimal external components, fixed-output simplicity, and robust protection are prioritized over ultra-high efficiency or ultra-small footprint.

FAQ

What is the maximum input voltage supported by the LM2597N-12/NOPB?

The LM2597N-12/NOPB supports a maximum input voltage of 40 V, as specified in the Recommended Operating Conditions table. This rating applies to the standard LM2597 family; the HV variant (LM2597HV) extends to 60 V. Exceeding 40 V on the LM2597N-12/NOPB may cause permanent damage, and absolute maximum ratings (45 V) are stress limits-not functional operating conditions.

Does the LM2597N-12/NOPB require external feedback resistors to set its output voltage?

No, the LM2597N-12/NOPB is a fixed-output version and does not require external feedback resistors. Its 12 V output is internally trimmed and verified across temperature and load. Pin 4 (Feedback) is unused and must remain unconnected-unlike the adjustable LM2597 versions, which rely on an external resistor divider to set VOUT.

How does the Bias Supply (VBS) pin improve efficiency in the LM2597N-12/NOPB?

The VBS pin allows the LM2597N-12/NOPB's internal circuitry to be powered from the regulated 12 V output instead of the higher input voltage. When VIN exceeds ~24 V, this reduces input current draw by ~4 mA and lowers junction temperature-improving overall efficiency by 3–5% in high-VIN/low-IOUT conditions, as confirmed in TI's Figure 19 and Figure 20 efficiency curves.

Can the LM2597N-12/NOPB be used in a positive-to-negative inverter configuration?

Yes, the LM2597N-12/NOPB can be configured as a positive-to-negative inverter by referencing its ground pin to the negative output and grounding the feedback pin. TI Application Note SNVS119D Figure 24 demonstrates this topology using the LM2597-5; the 12 V version works identically. Maximum output current depends on VIN and |VOUT|, with total voltage across the IC limited to 40 V.

What protection features are integrated into the LM2597N-12/NOPB?

The LM2597N-12/NOPB integrates thermal shutdown (activates at 150 °C junction temperature), peak current limiting (0.8 A typical), and an open-collector error flag that signals undervoltage conditions. It also supports external shutdown via Pin 5 and includes internal frequency compensation-eliminating the need for external loop compensation components in standard buck configurations.