Texas Instruments LM2586S-3.3/NOPB

Overview

LM2586S-3.3/NOPB from Texas Instruments is a monolithic 3-A step-up (boost) and flyback switching regulator IC with fixed 3.3-V output, 4-V to 40-V input range, internal 3-A NPN switch rated for 65-V standoff, current-mode control, and adjustable 100–200-kHz switching frequency. It delivers stable power in industrial DC-DC conversion where wide VIN and high efficiency are required.

For engineers reviewing the LM2586S-3.3/NOPB datasheet, LM2586S-3.3/NOPB pinout, LM2586S-3.3/NOPB application, or LM2586S-3.3/NOPB equivalent, key selection criteria include input voltage range compatibility, output current capability under thermal constraints, shutdown functionality via ON/OFF pin, frequency synchronization capability, and system-level output tolerance of ±4% over line and load.

Technical Context

The LM2586S-3.3/NOPB integrates a current-mode PWM controller with an internal 3-A NPN power switch capable of 65-V breakdown, enabling direct use in boost and flyback topologies without external high-voltage transistors. Its error amplifier features 1.23-V reference (for 3.3-V version, VREF = 3.3 V at FB pin), transconductance of 1.193 mmho, and voltage gain of 260 V/V.

Control architecture includes soft-start (11-μA ramp current), undervoltage lockout (3.3-V threshold), thermal shutdown, and cycle-by-cycle current limiting. Frequency is set via resistor on Pin 1 (100 kHz open, up to 200 kHz with 22-kΩ), and synchronization is supported via Pin 6 with 0.75-V threshold and 100-μA input current.

Key Specifications

Pinout & Package

LM2586S-3.3/NOPB is supplied in the KTW (DDPAK/TO-263-7) package: thermally enhanced surface-mount variant with exposed thermal pad, 14.986 mm × 10.16 mm body size, and 7-pin staggered lead configuration optimized for high-power dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-up/flyback regulator applications.

Compared with LM2587S-3.3/NOPB and TPS55340RTER, the LM2586S-3.3/NOPB provides optimal balance of integration (no feedback divider), proven flyback suitability, and thermal robustness in the DDPAK package - making it ideal for space- and reliability-constrained industrial and automotive power stages.

Availability

LM2586S-3.3/NOPB is available at Aetrix Electronics and suitable for industrial power supplies, automotive body electronics, and telecom remote units requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for LM2586S-3.3/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 leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in high-reliability power conversion ICs.

The LM2586 series was designed specifically for cost-sensitive, high-efficiency flyback, boost, and forward converter applications in industrial, automotive, and telecom infrastructure - emphasizing minimal external component count and robust fault protection.

FAQ

What is the maximum input voltage rating for LM2586S-3.3/NOPB?

The absolute maximum input voltage for LM2586S-3.3/NOPB is 45 V, but the recommended operating range is 4 V to 40 V. Exceeding 40 V risks violating safe operating area limits, especially under transient conditions. The device's internal 65-V switch provides margin, yet sustained operation above 40 V may compromise reliability and thermal performance - always verify derating per application-specific thermal design.

Does LM2586S-3.3/NOPB require an external feedback resistor divider?

No, LM2586S-3.3/NOPB does not require an external feedback resistor divider because it is a fixed-output variant with internal 3.3-V regulation. The feedback pin (Pin 3) connects directly to the output, eliminating resistor tolerance errors and temperature drift. This simplifies layout, improves accuracy, and reduces BOM count compared to adjustable versions like LM2586SX-ADJ/NOPB.

Can LM2586S-3.3/NOPB be used in flyback topology?

Yes, LM2586S-3.3/NOPB is explicitly designed for flyback operation, as confirmed in its product description and typical applications. Its current-mode control, 65-V switch standoff, and integrated protections (UVLO, thermal shutdown, current limit) make it suitable for isolated flyback converters. TI provides reference designs (e.g., Figure 16 in SNVS121E) demonstrating 3.3-V flyback implementation with transformer and rectifier selection guidance.

What is the purpose of Pin 1 on LM2586S-3.3/NOPB?

Pin 1 on LM2586S-3.3/NOPB serves dual functions: frequency adjustment (when connected to ground via resistor) and external shutdown control (when ≥3 V is applied). To use both simultaneously, TI specifies an isolation diode between the control signal and Pin 1. Without proper isolation, applying shutdown voltage interferes with frequency setting - correct implementation ensures independent control of switching frequency and enable/disable state.

How does LM2586S-3.3/NOPB handle thermal management in the KTW package?

LM2586S-3.3/NOPB in the KTW (DDPAK/TO-263-7) package achieves thermal resistance of 35°C/W (with 0.4896 in² copper) or 26°C/W (with 1.0064 in² copper), significantly better than the TO-220 variant. Effective thermal management requires soldering the exposed thermal pad to a large copper pour, using multiple thermal vias to inner/ground planes, and avoiding silkscreen or solder mask over the pad. TI's layout guidelines (Section 9.3) specify minimum copper area and via count to maintain junction temperature ≤125°C under full 3-A load.