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Texas Instruments LM2577T-15/LF03
- Part No.:
- LM2577T-15/LF03
- Manufacturer:
- Texas Instruments
- Package:
- TO-220-5 Formed Leads
- Datasheet:
-
LM2577T-15/LF03.pdf
- Description:
- IC REG BST FLYBCK 15V 3A TO220-5
- Quantity:
- Payment:
- Shipping:
Inventory:4,269
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Product details
Overview
LM2577T-15/LF03 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. It operates from 3.5 V to 40 V input and delivers up to 600 mA load current in boost configuration-used in industrial power supplies, battery-powered instrumentation, and distributed DC-DC conversion where compact, low-component-count regulation is required.
For engineers reviewing the LM2577T-15/LF03 datasheet, LM2577T-15/LF03 pinout, LM2577T-15/LF03 application, or LM2577T-15/LF03 equivalent, key selection criteria include its TO-220 (T) package thermal performance (θJA = 65°C/W), 15 V ±3% output tolerance over temperature, undervoltage lockout at 2.7–3.15 V, soft-start function, and compatibility with standard off-the-shelf flyback inductors such as AIE L47–L680 series.
Technical Context
The LM2577T-15/LF03 implements current-mode 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 an NPN output switch rated for 65 V standoff and 3.0 A continuous current, with protection via thermal shutdown, current limiting, and undervoltage lockout.
It functions exclusively in boost, flyback, or forward converter topologies-requiring external diode, inductor, and input/output capacitors. The feedback pin is internally connected to the 15 V output for fixed-voltage versions, eliminating external resistor dividers and simplifying layout for single-output applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 15 V ±3% (14.25–15.75 V) across 100–600 mA load and −40°C to +125°C junction range |
| Input Voltage Range | 3.5 V to 40 V-supports wide-range DC inputs including 5 V, 12 V, and 24 V rails and battery-derived supplies |
| Switch Current Rating | 3.0 A continuous NPN switch-limits peak inductor current to prevent saturation and ensures stable operation in boost mode |
| Oscillator Frequency | 52 kHz ±8% (42–62 kHz)-enables use of low-cost, high-inductance off-the-shelf inductors while minimizing EMI |
| Efficiency | ≥80% at VIN = 5 V, ILOAD = 600 mA-reduces thermal load in enclosed or convection-cooled environments |
| UVLO Threshold | 2.70–3.15 V-prevents erratic startup during brownout or weak battery conditions |
| Soft-Start Current | 2.5–9.5 μA-controls ramp rate of output voltage to limit inrush into bulk capacitance |
Pinout & Package
LM2577T-15/LF03 is housed in a 5-lead TO-220 (T) package (NS package code T05A), with the tab electrically connected to Pin 2 (Ground) and thermally coupled to the PCB copper pour for heat dissipation. Thermal resistance is θJA = 65°C/W (with minimal copper) and θJC = 2°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1: Input | Power input connection | Accepts 3.5–40 V DC; requires local 100 μF+ input capacitor for stability and transient suppression |
| Pin 2: Ground | Circuit common and thermal path | Tab-connected ground-must be soldered to ≥1 sq-in copper area for thermal management |
| Pin 3: Feedback | Output voltage sensing node | Internally tied to 15 V output; no external divider needed for fixed-voltage operation |
| Pin 4: Switch | NPN collector output | Drives external flyback diode and inductor; switches at 52 kHz with 0.5–0.9 V saturation |
| Pin 5: Output | Regulated 15 V supply | Delivers up to 600 mA; requires ≥680 μF output capacitor (e.g., Sprague 673D) for ripple control |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 3.0 A NPN switch | Eliminates need for external transistor and drive circuitry-reduces BOM count and layout complexity |
| Current-mode control architecture | Provides inherent cycle-by-cycle current limiting and improves line/load transient response without compensation network |
| 52 kHz fixed-frequency oscillator | Enables predictable EMI filtering and compatibility with standardized inductor families (e.g., AIE, Pulse, Renco) |
| Soft-start function | Gradually ramps output voltage to avoid inrush current spikes into downstream capacitors and loads |
| Thermal shutdown & UVLO protection | Prevents device damage during overload, ambient overheating, or insufficient input voltage conditions |
Applications
| Industrial Sensor Power Supply | Portable Test Equipment |
|---|---|
Use Scenario: Powers analog front-end circuits (ADCs, op-amps, transducers) in 4–20 mA loop-powered sensors operating from 12 V nominal rail. IC Role / Device Role / Timing Role: Step-up regulator generating stable 15 V bias from 12 V input-enabling higher dynamic range and noise margin in signal conditioning stages. Use Value: Delivers regulated 15 V at ≤600 mA with <100 mV load/line regulation, supporting precision measurement accuracy without external LDO post-regulation. | Use Scenario: Supplies 15 V to microcontroller peripherals and display drivers in handheld multimeters and oscilloscope probes. IC Role / Device Role / Timing Role: Boost converter converting 3.7 V Li-ion battery voltage to fixed 15 V-enabling legacy analog ICs requiring higher supply rails. Use Value: Operates down to 3.5 V input with soft-start, ensuring clean power-up during battery discharge; efficiency ≥80% extends usable runtime per charge cycle. |
| Automotive Aftermarket Lighting | Distributed Control Node |
Use Scenario: Drives white LED arrays in 12 V vehicle systems requiring >15 V forward voltage (e.g., 3×LED string). IC Role / Device Role / Timing Role: Constant-voltage boost controller feeding LED driver IC-providing stable headroom for current regulation stage. Use Value: Withstands automotive load dump transients up to 40 V input and includes built-in UVLO to prevent flicker during cranking (low-battery) events. | Use Scenario: Generates local 15 V rail for isolated RS-485 transceivers and CAN interface ICs in modular PLC backplanes. IC Role / Device Role / Timing Role: Primary DC-DC stage converting 24 V system bus to 15 V intermediate rail-feeding isolated DC-DC modules and level translators. Use Value: Fixed 15 V output eliminates feedback resistor tuning; TO-220 package allows direct heatsinking to chassis for reliable operation in 70°C ambient industrial enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-up regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2577T-12/LF03 | Fixed 12 V output; identical pinout, thermal specs, and electrical characteristics except VOUT and reference voltage (12 V vs 15 V) | Suitable only where 12 V output is acceptable-requires redesign of downstream voltage margins and load compatibility | Select when system loads are rated for 12 V and higher efficiency at lower output voltage is prioritized |
| LM2577T-ADJ/LF03 | Adjustable output (1.23–60 V) via external resistor divider; same package, switch rating, and oscillator, but requires two precision resistors and additional layout space | Used where multiple output voltages are needed on one board or future voltage flexibility is required | Choose for design reuse across variants or when 15 V is not the final target-adds BOM cost and calibration overhead |
Compared with LM2577T-12/LF03 and LM2577T-ADJ/LF03, the LM2577T-15/LF03 provides optimal integration for fixed 15 V systems-eliminating external feedback components while maintaining identical thermal, switching, and protection behavior-making it the most cost- and space-efficient choice for dedicated 15 V boost applications.
Availability
LM2577T-15/LF03 is available at Aetrix Electronics and suitable for industrial sensor power supplies, portable test equipment, automotive lighting controllers, and distributed control nodes requiring stable component supply with long-term manufacturability.
Supply support for LM2577T-15/LF03 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 switching regulator design.
The LM2577 product line was engineered for cost-sensitive, medium-power DC-DC conversion in industrial, automotive, and instrumentation applications-emphasizing simplicity, reliability, and minimal external component count.
FAQ
What is the maximum output current capability of the LM2577T-15/LF03 in a boost configuration?
The LM2577T-15/LF03 supports up to 600 mA output current in boost topology under typical conditions (VIN = 5 V, TJ ≤ 125°C), as specified in the Electrical Characteristics table for LM2577-15. This assumes proper thermal management using the TO-220 tab and ≥1 square inch of PCB copper. Exceeding this current risks thermal shutdown or switch current-limit activation.
Does the LM2577T-15/LF03 require external feedback resistors to set the output voltage?
No-the LM2577T-15/LF03 has an internal feedback connection that fixes the output to 15 V. Pin 3 (Feedback) is internally tied to the output, so no external resistor divider is needed. This distinguishes it from the adjustable LM2577T-ADJ/LF03 version, which requires two precision resistors to configure VOUT.
Can the LM2577T-15/LF03 be used in flyback or forward converter topologies?
Yes-the LM2577T-15/LF03 is explicitly designed for boost, flyback, and forward converter applications per its datasheet description. In flyback mode, it provides internal current limiting and supports transformer-coupled outputs; in forward mode, it requires a reset winding or RCD clamp. All topologies share the same 52 kHz oscillator and 3.0 A NPN switch.
What is the purpose of the soft-start function in the LM2577T-15/LF03, and how is it implemented?
The soft-start function in the LM2577T-15/LF03 limits inrush current during power-up by gradually increasing the duty cycle of the internal switch. It is implemented via a 2.5–9.5 μA current source charging the compensation pin's external capacitor-controlling the ramp rate of the error amplifier output and thus the output voltage rise time.
How does the LM2577T-15/LF03 handle input undervoltage conditions?
The LM2577T-15/LF03 incorporates an undervoltage lockout (UVLO) circuit that disables the internal switch when input voltage falls below 2.70 V (min) and re-enables it above 3.15 V (max). This prevents erratic switching, output instability, or excessive quiescent current draw during brownout or battery-depletion scenarios-ensuring clean startup and shutdown behavior.
LM2577T-15/LF03 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-220-5 Formed Leads
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Boost, Flyback, Forward Converter
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3.5V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 15V
- Voltage - Output (Max):
- -
- Current - Output:
- 3A (Switch)
- Frequency - Switching:
- 52kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220-5
LM2577T-15/LF03 FAQ
1.How can I place an order for LM2577T-15/LF03 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2577T-15/LF03 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LM2577T-15/LF03 reliable?
The price and inventory of LM2577T-15/LF03 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2577T-15/LF03 is usually 5 days.
3.What payment methods are accepted for LM2577T-15/LF03?
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4.How is shipping managed for LM2577T-15/LF03?
LM2577T-15/LF03 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2577T-15/LF03 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LM2577T-15/LF03?
For technical support, including LM2577T-15/LF03 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2577T-15/LF03 requirements.
6.How does Aetrix verify that LM2577T-15/LF03 is sourced from the original manufacturer or authorized distributors?
All LM2577T-15/LF03 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LM2577T-15/LF03 meets industry standards.
7.What is the process for return or replacement of LM2577T-15/LF03?
All LM2577T-15/LF03 units undergo pre-shipment inspection (PSI). If there is an issue with LM2577T-15/LF03, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LM2577T-15/LF03 part is unused and in its original packaging.
Return procedure for LM2577T-15/LF03:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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