Texas Instruments LM2578AN

Overview

LM2578AN from Texas Instruments is a monolithic switching regulator controller IC featuring an integrated NPN output transistor, dual comparator inputs (inverting and non-inverting), internal 1.0 V reference, and on-chip oscillator. It supports buck, boost, and inverting DC-DC topologies with up to 750 mA output current, 2 V to 40 V input range, and duty cycle up to 90%. Used in industrial power supplies and motor control circuits where compact, low-component-count regulation is required.

For engineers reviewing the LM2578AN datasheet, LM2578AN pinout, LM2578AN application, or LM2578AN equivalent, key selection criteria include its 1.0 V reference accuracy, collector saturation voltage ≤0.9 V at 750 mA, ground- or VIN-referenced current limit sensing, and oscillator frequency set by a single external capacitor (20 kHz typical).

Technical Context

The LM2578AN implements a pulse-width modulation architecture with a unique dual-input comparator stage that provides independent 1.0 V references to both inverting and non-inverting pins-enabling direct feedback without external op-amps in inverting configurations. Its oscillator sets switching frequency via a single timing capacitor (CT), supporting 20 kHz typical operation with ±0.13%/°C drift.

Output control uses an internal NPN transistor with separate collector and emitter terminals, allowing flexible topology implementation. Current limiting operates cycle-by-cycle with 110 mV sense threshold referenced either to ground or VIN, and thermal shutdown protects against junction temperatures exceeding 150°C.

Key Specifications

Pinout & Package

LM2578AN is packaged in an 8-pin plastic DIP (Dual In-line Package), designated Package Number P0008E per TI documentation. This through-hole package supports prototyping and legacy board designs with standard 0.3-inch lead spacing.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar switching regulator controller applications.

Compared with LM2578AN, LM2576HVS-5.0 delivers higher output current in a simpler fixed-output buck configuration, while UC3843B offers greater control loop flexibility at the cost of increased external component count and no integrated reference-making LM2578AN optimal for cost-sensitive, multi-topology designs requiring minimal external parts.

Availability

LM2578AN is available at Aetrix Electronics and suitable for industrial power supplies, motor control circuits, and embedded DC-DC conversion requiring stable component supply, long-lifecycle support, and through-hole manufacturability.

Supply support for LM2578AN 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 experience in high-reliability industrial and automotive ICs.

The LM2578A series was designed as a versatile, low-component-count switching regulator controller for buck, boost, and inverting DC-DC applications-targeting cost-sensitive industrial equipment and legacy-compatible power designs.

FAQ

What is the maximum allowable voltage on the LM2578AN collector pin?

The LM2578AN collector pin has an absolute maximum rating of +50 V relative to ground. However, its sustained collector-emitter sustaining voltage (BV_CEO(SUS)) is specified at 60 V under pulsed conditions (I_SUST = 0.2 A). For reliable continuous operation, TI recommends limiting collector-to-ground voltage to ≤40 V in practical designs. The LM2578AN datasheet confirms this rating applies directly to the LM2578AN device under normal operating conditions.

Can the LM2578AN be used in a synchronous rectifier configuration?

No, the LM2578AN does not support synchronous rectification. It features an internal NPN bipolar transistor with separate collector and emitter terminals, but lacks gate-drive outputs or timing control for external MOSFETs. Its architecture relies on external diodes (e.g., Schottky 1N5818) for freewheeling paths in buck/boost topologies. The LM2578AN datasheet makes no provision for synchronous FET control signals or dead-time management.

What is the minimum input voltage required for stable operation of the LM2578AN?

The LM2578AN specifies a minimum operating input voltage of 2 V across the full temperature range, with a typical lower limit of 2.2 V at junction temperatures ≤−25°C. This allows operation from single-cell LiFePO₄ or two-cell alkaline supplies. The internal 1.0 V reference and oscillator remain functional down to 2 V, as confirmed in the Electrical Characteristics table of the LM2578AN datasheet.

How does the LM2578AN implement current limiting-pin 3 or pin 8 referenced?

The LM2578AN current limit function (pin 3) can be referenced to either ground (pin 2) or VIN (pin 8), depending on external resistor placement. When referenced to ground, a sense resistor between pin 3 and ground triggers shutdown at ~110 mV. When referenced to VIN, the same resistor connects between pin 3 and pin 8-producing the same 110 mV differential threshold. This dual-reference capability is explicitly documented in the LM2578AN Functional Description and Applications Information sections.

Is the LM2578AN RoHS compliant and lead-free?

Yes, the LM2578AN is RoHS compliant and lead-free. Texas Instruments certifies the LM2578AN as meeting JEDEC J-STD-020 moisture sensitivity level 1 and RoHS Directive 2011/65/EU requirements. The device uses matte tin lead finish and Pb-free mold compound, with full compliance data available in TI's official product change notices (PCNs) for the LM2578A family. This applies specifically to the LM2578AN variant.