Texas Instruments LM2577T-15

Overview

LM2577T-15 from Texas Instruments is a monolithic step-up (boost) switching voltage regulator with fixed 15 V output, integrated 3.0 A NPN switch, 52 kHz oscillator, and current-mode control architecture. 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-used in industrial power supplies and battery-powered instrumentation.

For engineers reviewing the LM2577T-15 datasheet, LM2577T-15 pinout, LM2577T-15 application, or LM2577T-15 equivalent, key selection considerations include its TO-220 (T) package thermal performance (θ_JA = 65°C/W), fixed-output topology eliminating external feedback resistors, soft-start function for in-rush current control, and compatibility with standard off-the-shelf boost inductors such as AIE L415-0930.

Technical Context

The LM2577T-15 implements current-mode PWM control using an internal error amplifier with 15 V reference voltage, transconductance of 300 μmho (min), and voltage gain of 40 V/V (min). Its 52 kHz fixed-frequency oscillator drives the NPN switch directly, enabling predictable EMI behavior and simplified filter design.

Operation relies on external components: a diode, inductor (e.g., AIE 415-0930), input capacitor, and output capacitor (680 μF, 20 V electrolytic per Figure 9). The feedback pin is internally connected to the 15 V output-no external resistor divider required-simplifying layout and improving regulation accuracy over temperature (±0.5% typical line/load regulation).

Key Specifications

Pinout & Package

LM2577T-15 uses a 5-lead TO-220 (T) package (NS package code T05A), with the tab electrically connected to Pin 2 (Ground). Thermal performance depends on PCB copper area; full-rated current requires ≥1 in² of copper connected to the tab.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2577S-15 and LM2577M-15, the LM2577T-15 offers optimal balance of thermal performance, mechanical robustness, and through-hole manufacturability - making it preferred for prototyping, industrial repair, and medium-volume production where TO-220 mounting is acceptable.

Availability

LM2577T-15 is available at Aetrix Electronics and suitable for industrial power supplies, portable test equipment, automotive aftermarket modules, and legacy control panel upgrades requiring stable component supply and long-term obsolescence management.

Supply support for LM2577T-15 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 ICs and industrial-grade reliability.

The LM2577 family was designed specifically for cost-sensitive, medium-power DC/DC conversion in industrial, automotive, and instrumentation applications - emphasizing simplicity, thermal resilience, and minimal external component count.

FAQ

What is the maximum output current achievable with LM2577T-15?

The LM2577T-15 supports up to 600 mA continuous output current under typical conditions (VIN = 5 V, TA = 25°C, with adequate PCB copper). At lower input voltages or elevated ambient temperatures, output current must be derated due to thermal limits - the TO-220 package's θ_JA = 65°C/W requires ≥1 in² copper pour to sustain full rated switch current. The LM2577T-15 datasheet specifies 600 mA as the validated load current for system-level efficiency and regulation performance.

Does LM2577T-15 require external feedback resistors?

No. The LM2577T-15 has an internally trimmed 15 V reference and direct internal connection from the feedback pin to the output, eliminating the need for external resistors. This configuration ensures factory-calibrated output accuracy and removes resistor tolerance and temperature drift as error sources. In contrast, the LM2577T-ADJ variant requires two external resistors to set output voltage - the LM2577T-15 is optimized for fixed-output simplicity and stability.

Can LM2577T-15 operate from a 3.3 V input source?

No. The LM2577T-15 has a minimum input voltage of 3.5 V per its operating ratings, and undervoltage lockout activates below approximately 2.7 V. A 3.3 V source falls below the guaranteed operational range and will not enable the device. For 3.3 V input boost applications, consider alternatives such as the TPS61040 or MAX1706 - the LM2577T-15 is intended for ≥3.5 V inputs like 5 V logic rails, 12 V batteries, or 24 V industrial buses.

What inductor is recommended for LM2577T-15 in a standard boost configuration?

Texas Instruments specifies the AIE 415-0930 (or equivalent) as the reference inductor for the LM2577T-15 in Figure 9 of the datasheet. This 415 μH, 3.0 A saturation-current ferrite pot-core inductor is optimized for 52 kHz operation and matches the device's current-mode control characteristics. Using non-specified inductors may cause instability, excessive ripple, or premature current-limit triggering - the LM2577T-15 performance is validated with this part.

How does the soft-start function work in LM2577T-15?

The LM2577T-15 implements soft-start by gradually increasing the PWM duty cycle during power-up, limiting in-rush current into the output capacitor. This is achieved via an internal 5 μA current source charging the compensation pin capacitor, which controls the error amplifier's output swing. As a result, output voltage ramps smoothly over ~10 ms - preventing input voltage sag, diode stress, and system reset events. This behavior is intrinsic to the LM2577T-15 and requires no external components.