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Texas Instruments LM2577T-12/LF03
- Part No.:
- LM2577T-12/LF03
- Manufacturer:
- Texas Instruments
- Package:
- TO-220-5 Formed Leads
- Datasheet:
-
LM2577T-12/LF03.pdf
- Description:
- IC REG BST FLYBCK 12V 3A TO220-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,562
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Product details
Overview
LM2577T-12/LF03 from Texas Instruments is a monolithic step-up (boost) switching voltage regulator with fixed 12 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 800 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-12/LF03 datasheet, LM2577T-12/LF03 pinout, LM2577T-12/LF03 application, or LM2577T-12/LF03 equivalent, key selection criteria include input voltage range compatibility, output current capability under thermal constraints, feedback configuration for fixed-output operation, and TO-220 package thermal resistance (θJA = 65°C/W).
Technical Context
The LM2577T-12/LF03 implements current-mode PWM control with an internal 52 kHz oscillator and error amplifier referenced to a stable 12 V output voltage. Its NPN switch supports 3.0 A continuous current and 65 V off-state voltage rating, enabling boost topologies where input-to-output differential exceeds linear regulator limits.
Operation relies on external inductor energy storage and diode rectification; feedback is internally connected for fixed 12 V output, eliminating external resistor dividers. Soft-start reduces in-rush current, while undervoltage lockout disables switching below ~2.7 V input to prevent erratic startup.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 12 V ±4% over 100–800 mA load and 3.5–40 V input; enables direct replacement of 12 V linear regulators without feedback network redesign. |
| Input Voltage Range | 3.5 V to 40 V; supports wide-range DC inputs including automotive (9–16 V), industrial 24 V rails, and multi-cell battery stacks. |
| Switch Current Rating | 3.0 A continuous (6.0 A absolute max); defines maximum inductor peak current and limits achievable output power at low input voltages. |
| Oscillator Frequency | 52 kHz nominal (42–62 kHz over temp); determines inductor size trade-off-lower frequency allows larger, lower-cost magnetics with reduced core loss. |
| Thermal Resistance | θJA = 65°C/W (TO-220 package); requires ≥1 in² copper pour for full 3.0 A operation at ambient ≤50°C without derating. |
| Protection Features | Integrated undervoltage lockout (~2.7 V), thermal shutdown, and current limiting; eliminates need for external fault management circuitry. |
Pinout & Package
LM2577T-12/LF03 uses a 5-lead TO-220 (T) package (NS package code T05A) with the tab electrically connected to Pin 2 (Ground). The package provides mechanical robustness and moderate thermal performance suitable for medium-power boost applications.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 – Input | Power input connection | Accepts 3.5–40 V DC; requires local 100 μF low-ESR capacitor near pin for stability and transient response. |
| 2 – Ground | Reference and return path | Tab-connected ground plane; must be thermally and electrically tied to large PCB copper area for heat dissipation and noise control. |
| 3 – Output Switch | NPN collector output | Drives external flyback diode and inductor; switches at 52 kHz with 0.7 V saturation voltage at 2 A. |
| 4 – Feedback | Regulation sense node | Internally tied to 12 V output; no external resistors required-simplifies layout and improves regulation accuracy. |
| 5 – Bypass | Internal oscillator timing | Connects to 0.1 μF ceramic capacitor to ground; sets oscillator frequency and stabilizes internal timing reference. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 3.0 A NPN switch | Eliminates external transistor and driver, reducing BOM count and layout complexity in boost converters up to ~25 W. |
| Current-mode control | Provides inherent cycle-by-cycle current limiting, fast transient response to load steps, and stable operation across wide input/output ratios. |
| Soft-start function | Gradually ramps output voltage over ~10 ms, preventing in-rush current surges into bulk output capacitors during power-up. |
| Fixed-frequency 52 kHz operation | Enables predictable EMI filtering design and consistent inductor sizing; avoids subharmonic oscillation issues seen in variable-frequency controllers. |
| Undervoltage lockout (UVLO) | Disables switching below ~2.7 V input, preventing unstable operation and potential damage during brownout or cold-cranking conditions. |
Applications
| Industrial Power Supply | Battery-Powered Instrumentation |
|---|---|
Use Scenario: Generating stable 12 V rail from 5 V or 9 V DC input in programmable logic controllers and sensor transmitters. IC Role / Device Role / Timing Role: Primary DC-DC boost controller managing energy transfer via external inductor and Schottky diode. Use Value: Delivers regulated 12 V at up to 800 mA with >80% efficiency, replacing inefficient linear regulators and extending system runtime. |
Use Scenario: Powering analog front-ends and microcontrollers from aging or partially discharged 2S Li-ion packs (6–8.4 V). IC Role / Device Role / Timing Role: Fixed-output boost regulator maintaining constant 12 V supply despite falling battery voltage. Use Value: Enables full functionality down to 3.5 V input, supporting extended battery life without requiring voltage monitoring or dynamic reconfiguration. |
| Automotive Aftermarket Electronics | Point-of-Load Conversion |
Use Scenario: Providing isolated 12 V for CAN transceivers and display modules in 24 V commercial vehicle systems. IC Role / Device Role / Timing Role: Step-up regulator converting 24 V nominal bus to 12 V auxiliary rail with built-in UVLO for cold-crank immunity. Use Value: Withstands 40 V transients and operates reliably during 6 V cranking events, ensuring uninterrupted communication and display operation. |
Use Scenario: Local 12 V generation for op-amp biasing or relay drivers in mixed-signal embedded systems with distributed 5 V/3.3 V rails. IC Role / Device Role / Timing Role: Compact, self-contained boost stage minimizing routing of high-current paths across main PCB. Use Value: Reduces noise coupling into sensitive analog sections by localizing switching energy and using short, controlled inductor-diode loops. |
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 | Same die, identical electrical specs; differs only in flow code (LF03 vs blank)-no functional distinction. | No difference; both rated for −40°C to +125°C junction temperature and share same TO-220 package and pinout. | Select LM2577T-12/LF03 when traceability to TI's LF03 manufacturing flow is required per procurement specification. |
| LM2577S-12 | Identical functionality but in TO-263 (S) surface-mount package with θJA = 37°C/W (1 in² copper), versus 65°C/W for TO-220. | Enables higher power density and automated assembly; requires different thermal pad layout and reflow profile. | Choose LM2577S-12 for space-constrained or SMT-only designs where thermal performance must exceed TO-220 limits. |
Compared with LM2577T-12/LF03, the base LM2577T-12 offers identical performance with no flow-code traceability, while LM2577S-12 delivers superior thermal efficiency in surface-mount layouts-making the choice dependent on assembly method, thermal budget, and supply chain requirements.
Availability
LM2577T-12/LF03 is available at Aetrix Electronics and suitable for industrial power supplies, battery-powered instrumentation, automotive aftermarket electronics, and point-of-load conversion requiring stable component supply and long-term manufacturability.
Supply support for LM2577T-12/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 ICs, with decades of expertise in switching regulator design and manufacturing.
The LM2577 family was engineered as part of TI's SIMPLE SWITCHER® portfolio to deliver cost-effective, easy-to-use boost and flyback solutions for industrial, automotive, and consumer power applications-emphasizing minimal external components and robust protection.
FAQ
What is the maximum output current capability of the LM2577T-12/LF03?
The LM2577T-12/LF03 supports up to 800 mA continuous output current under typical conditions (VIN ≥5 V, ambient ≤50°C, with adequate PCB copper). At lower input voltages or elevated temperatures, output current must be derated due to thermal limits-its 3.0 A switch rating defines peak inductor current, not sustained load current. Full 800 mA operation requires θJA ≤65°C/W and proper heatsinking of the TO-220 tab.
Does the LM2577T-12/LF03 require external feedback resistors?
No, the LM2577T-12/LF03 does not require external feedback resistors. It integrates internal resistor division to set the output to exactly 12 V, with the feedback pin (Pin 4) internally connected to the output. This simplifies design, improves regulation accuracy, and eliminates resistor tolerance and drift errors common in adjustable versions like LM2577T-ADJ.
Can the LM2577T-12/LF03 operate from a 3.5 V input source?
Yes, the LM2577T-12/LF03 is specified to operate from 3.5 V minimum input. However, at this voltage, duty cycle approaches 95%, requiring careful inductor selection to avoid saturation and maintain stability. Efficiency drops significantly below 5 V input, and output current capability is reduced due to higher switch conduction losses and thermal constraints.
What diode type is recommended for use with the LM2577T-12/LF03?
A Schottky diode with ≥60 V PIV rating and ≥3 A average current rating is recommended for the LM2577T-12/LF03. TI specifies VF ≈ 0.5 V for Schottky devices, minimizing conduction loss and improving efficiency. Fast-recovery diodes (VF ≈ 0.8 V) may be used but reduce efficiency and increase thermal stress on the output capacitor and diode.
How does the soft-start function of the LM2577T-12/LF03 improve system reliability?
The soft-start function in the LM2577T-12/LF03 gradually increases output voltage over ~10 ms at startup, limiting in-rush current into bulk output capacitors. This prevents tripping of upstream current-limiting circuits, reduces mechanical stress on electrolytic capacitors, and avoids voltage droop on shared input rails-enhancing overall system robustness during repeated power cycles.
LM2577T-12/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):
- 12V
- 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-12/LF03 FAQ
1.How can I place an order for LM2577T-12/LF03 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2577T-12/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-12/LF03 reliable?
The price and inventory of LM2577T-12/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-12/LF03 is usually 5 days.
3.What payment methods are accepted for LM2577T-12/LF03?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2577T-12/LF03 transactions.
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4.How is shipping managed for LM2577T-12/LF03?
LM2577T-12/LF03 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2577T-12/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-12/LF03?
For technical support, including LM2577T-12/LF03 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2577T-12/LF03 requirements.
6.How does Aetrix verify that LM2577T-12/LF03 is sourced from the original manufacturer or authorized distributors?
All LM2577T-12/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-12/LF03 meets industry standards.
7.What is the process for return or replacement of LM2577T-12/LF03?
All LM2577T-12/LF03 units undergo pre-shipment inspection (PSI). If there is an issue with LM2577T-12/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-12/LF03 part is unused and in its original packaging.
Return procedure for LM2577T-12/LF03:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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