Texas Instruments LM2577N-15/NOPB

Overview

LM2577N-15/NOPB from Texas Instruments is a monolithic step-up (boost) switching voltage regulator IC with fixed 15 V output, integrated 3.0 A NPN switch, 52 kHz oscillator, and current-mode control. It operates from 3.5 V to 40 V input, delivers up to 600 mA load current, and includes undervoltage lockout, thermal shutdown, and current limiting. It is used in industrial power supplies where compact, low-component-count DC-DC conversion is required.

For engineers reviewing the LM2577N-15/NOPB datasheet, LM2577N-15/NOPB pinout, LM2577N-15/NOPB application, or LM2577N-15/NOPB equivalent, key selection criteria include its fixed 15 V output, TO-220-16 package thermal performance (θ_JA = 85°C/W), 3.0 A internal switch rating, soft-start function for in-rush current control, and compatibility with standard off-the-shelf boost inductors such as AIE L47–L680 series.

Technical Context

The LM2577N-15/NOPB implements current-mode control using an internal error amplifier (transconductance = 300 μmho typ.), reference voltage of 15.0 V (min 14.50 V, max 15.50 V at I_LOAD = 100–600 mA), and comparator-based peak-current limiting. Its 52 kHz fixed-frequency oscillator eliminates external timing components and ensures predictable EMI behavior.

It uses a single-ended NPN switch (V_SWITCH ≤ 60 V, I_SWITCH ≤ 3.0 A continuous) with saturation voltage of 0.5 V (typ.) at 2.0 A, enabling efficient energy transfer in boost, flyback, and forward topologies. Soft-start reduces startup in-rush by linearly ramping the internal current limit threshold over ~10 ms.

Key Specifications

Pinout & Package

LM2577N-15/NOPB uses a 16-pin dual-in-line (DIP) plastic package (NS package code N16A), with pins 1–8 on one side and 9–16 on the other. The package has no internal connection on pins 1 and 16 per Figure 3; these are NC terminals.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2577T-15/NOPB, the LM2577N-15/NOPB offers superior board-level integration in space-constrained DIP layouts but trades 20°C/W higher θ_JA; versus LM2587N-15/NOPB, it provides proven field reliability and cost advantage where 80% efficiency suffices and 3.5 V start-up is critical.

Availability

LM2577N-15/NOPB is available at Aetrix Electronics and suitable for industrial sensor power supplies, portable medical instrumentation, automotive display systems, and legacy PLC module replacements requiring stable component supply and long-term obsolescence support.

Supply support for LM2577N-15/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 and embedded processing technologies, with decades of expertise in power management IC design and manufacturing.

The LM2577 product line was engineered for cost-sensitive, medium-power DC-DC conversion in industrial, automotive, and instrumentation applications-emphasizing simplicity, robustness, and minimal external component count.

FAQ

What is the minimum input voltage required for LM2577N-15/NOPB to start regulation?

The LM2577N-15/NOPB features an undervoltage lockout circuit that disables operation below approximately 2.70 V. However, reliable startup and regulation at 15 V output require a minimum input voltage of 3.5 V per the Absolute Maximum Ratings table. Below this, the internal switch cannot sustain sufficient duty cycle to maintain output regulation, even if the device powers up.

Can LM2577N-15/NOPB be used in flyback or forward converter topologies?

Yes, the LM2577N-15/NOPB is explicitly designed for flyback and forward converter applications per its datasheet description and Application Hints section. Its current-mode architecture, 65 V switch standoff voltage, and internal protection make it suitable for isolated topologies-though external transformer design and snubber components must comply with TI's recommended practices in SNOS658C.

What is the purpose of the NC pins (1 and 16) on the LM2577N-15/NOPB DIP package?

Pins 1 and 16 on the LM2577N-15/NOPB are designated No Connect (NC) per TI's N16A package drawing and Figure 3. They are unconnected die pads with no internal bond wires. These pins must remain electrically floating-no PCB traces, vias, or solder mask openings should be placed on them to avoid unintended coupling or mechanical stress.

How does the soft-start function operate in LM2577N-15/NOPB?

The LM2577N-15/NOPB soft-start function ramps the internal current limit threshold linearly over ~10 ms after enable, limiting peak inductor current during startup. This is controlled via the SS pin: leaving it open yields default ramp time; connecting a capacitor to GND extends it proportionally. It prevents input voltage droop and output overshoot in capacitive-load applications.

Is LM2577N-15/NOPB RoHS compliant and lead-free?

Yes, the /NOPB suffix in LM2577N-15/NOPB indicates "No Lead (Pb)-Free" per Texas Instruments' part numbering convention, confirming RoHS-compliant packaging and lead-free terminations. The device meets JEDEC J-STD-020 moisture sensitivity level (MSL) 3 and is qualified for Pb-free reflow soldering profiles.