Texas Instruments LM2586T-3.3/NOPB

Overview

LM2586T-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, NPN 65-V switch, current-mode control, and internal soft-start. It delivers ±4% system output voltage tolerance over line and load, supports frequency synchronization, and targets isolated or non-isolated DC-DC conversion in industrial power supplies.

For engineers reviewing the LM2586T-3.3/NOPB datasheet, LM2586T-3.3/NOPB pinout, LM2586T-3.3/NOPB application, or LM2586T-3.3/NOPB equivalent, key selection considerations include input voltage range compatibility, 3-A switch current capability, thermal design for TO-220/TO-263 packages, shutdown current (<60 μA), and fixed-output versus adjustable variants.

Technical Context

The LM2586T-3.3/NOPB implements current-mode control with cycle-by-cycle current limiting, an internal 1.23-V reference for feedback regulation, and a programmable oscillator (100–200 kHz) that supports external synchronization via Pin 6. Its error amplifier features transconductance of 1.193 mmho and voltage gain of 260 V/V at 25°C.

Operation includes undervoltage lockout (3.3 V threshold), thermal shutdown, and protection against switch overcurrent and saturation. The device uses an NPN power transistor with 0.45-V saturation voltage at 3 A and 65-V sustaining voltage, enabling robust operation in wide-input flyback and boost topologies.

Key Specifications

Pinout & Package

LM2586T-3.3/NOPB is available in NDZ (TO-220-7) and KTW (DDPAK/TO-263-7) packages. Both are 7-pin thermally enhanced through-hole/surface-mount packages with exposed thermal pad (KTW) or metal tab (NDZ) tied to Pin 2 (Ground).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2586T-3.3/NOPB, the 5-V variant offers identical form-factor and control features but targets different voltage rails, while the LM2588T-3.3/NOPB provides higher current and voltage ratings at the cost of larger magnetics and more demanding thermal design.

Availability

LM2586T-3.3/NOPB is available at Aetrix Electronics and suitable for industrial power supplies, isolated communication interfaces, automotive body electronics, and FPGA auxiliary rails requiring stable component supply and long-term manufacturability.

Supply support for LM2586T-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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The LM2586 series was designed as a cost-effective, low-component-count solution for flyback, boost, and forward converter applications - targeting engineers needing reliable, thermally robust DC-DC regulation without complex external circuitry.

FAQ

What is the maximum input voltage rating for the LM2586T-3.3/NOPB?

The LM2586T-3.3/NOPB has an absolute maximum input voltage rating of 45 V, with recommended operating range from 4 V to 40 V. Exceeding 45 V risks permanent damage to the internal NPN switch and control circuitry. For automotive applications with load dump transients, external TVS clamping is advised to keep VIN within safe limits during fault conditions.

Does the LM2586T-3.3/NOPB require external feedback resistors?

No, the LM2586T-3.3/NOPB does not require external feedback resistors because it integrates a precision 3.3-V output divider network internally. The FB pin is pre-connected to this network, eliminating BOM count and layout sensitivity associated with external resistor matching and thermal drift - a key advantage over adjustable versions like LM2586T-ADJ/NOPB.

How is thermal performance affected between TO-220 and TO-263 packages of the LM2586T-3.3/NOPB?

The TO-263 (KTW) package offers lower thermal resistance: 35°C/W with 0.49 in² copper versus 65°C/W for TO-220 (NDZ) with no heatsink. This allows the LM2586T-3.3/NOPB in TO-263 to sustain higher continuous output power at elevated ambient temperatures - critical for sealed enclosures or high-density PCBs where airflow is limited.

Can the LM2586T-3.3/NOPB be synchronized to an external clock?

Yes, the LM2586T-3.3/NOPB supports frequency synchronization via Pin 6 (SYNC). A negative-going pulse below 0.875 V triggers alignment of the internal oscillator, enabling precise phase control across multiple regulators. This feature is confirmed in Section 7.3.6 of the datasheet and verified in Figure 25 waveforms showing 700-ns delay from sync edge to switch turn-on.

What protection features are built into the LM2586T-3.3/NOPB?

The LM2586T-3.3/NOPB integrates undervoltage lockout (UVLO, 3.3 V threshold), thermal shutdown, and current-limit protection for its internal NPN switch. These functions are active during normal operation and do not require external components. The datasheet confirms current limiting at 4.0 A typical (3.0–7.0 A min/max), with thermal shutdown activating above 150°C junction temperature.