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Texas Instruments LM2577T-12/LB03
- Part No.:
- LM2577T-12/LB03
- Manufacturer:
- Texas Instruments
- Package:
- TO-220-5 Formed Leads
- Datasheet:
-
LM2577T-12/LB03.pdf
- Description:
- IC REG BST FLYBCK 12V 3A TO220-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,583
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Product details
Overview
LM2577T-12/LB03 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, current-mode control, and built-in undervoltage lockout, thermal shutdown, and current limiting. It operates from 3.5 V to 40 V input and delivers regulated 12 V output for medium-power DC-DC conversion in industrial power supplies.
For engineers reviewing the LM2577T-12/LB03 datasheet, LM2577T-12/LB03 pinout, LM2577T-12/LB03 application, or LM2577T-12/LB03 equivalent, key selection criteria include input voltage range compatibility, output current capability under thermal constraints, TO-220 package thermal resistance (θJA = 65°C/W), and fixed-output configuration versus adjustable alternatives.
Technical Context
The LM2577T-12/LB03 implements current-mode PWM control using an internal error amplifier with 12 V reference (for fixed-output variants), transconductance of 370 μmho, and voltage gain of 80 V/V. Its 52 kHz fixed-frequency oscillator drives the NPN switch directly without external timing components.
It employs soft-start to limit in-rush current, uses feedback from the output to regulate via internal reference comparison, and relies on external diode, inductor, and capacitors to complete the boost topology. The device is rated for 3.0 A continuous switch current and 65 V switch voltage standoff.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 12 V ±4% over load (100–800 mA) and line (3.5–10 V input), enabling stable rail generation without external resistive divider. |
| Input Voltage Range | 3.5 V to 40 V - supports wide-input applications including automotive battery (9–16 V), industrial 12/24 V rails, and multi-cell battery systems. |
| Switch Current Limit | 3.0 A typical continuous, 3.7–6.0 A min–max - defines maximum inductor peak current and constrains usable output power at given input voltage. |
| Oscillator Frequency | 52 kHz ±8% - determines minimum inductor size, EMI profile, and enables use of low-cost, high-saturation-current ferrite inductors. |
| Thermal Resistance | θJA = 65°C/W (TO-220 package) - requires ≥1 in² copper pour for full 3.0 A operation at ambient ≤75°C; derating needed above 85°C junction. |
| Protection Features | Undervoltage lockout (2.7–3.1 V), thermal shutdown, and current limiting - prevent damage during startup, overload, or high-temperature operation. |
Pinout & Package
LM2577T-12/LB03 is housed in a 5-lead TO-220 (T) package (NS package number T05A), with the tab electrically connected to Pin 2 (Ground). Thermal performance depends on PCB copper area and mounting method.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - Input | Power input (VIN) | Accepts 3.5–40 V DC; must be decoupled near pin with ≥100 μF low-ESR capacitor to handle pulsed switch current. |
| 2 - Ground | Power and signal ground | Common return for input, output, feedback, and internal circuitry; tab connection provides primary thermal path to heatsink or PCB copper. |
| 3 - Feedback | Output voltage sense | Internally tied to 12 V reference for fixed-output version; no external resistor network required - simplifies layout and improves stability. |
| 4 - Switch | NPN collector output | Drives external flyback diode and inductor; switches at 52 kHz; peak voltage reaches VOUT + VF (diode forward drop) during off-time. |
| 5 - Output | Regulated 12 V output | Delivers up to ~800 mA typical at >80% efficiency; requires ≥680 μF output capacitor (e.g., Sprague 673D) for ripple suppression. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 3.0 A NPN switch | Eliminates need for external transistor and driver, reducing BOM count and layout complexity in boost/flyback designs. |
| Current-mode PWM control | Provides inherent cycle-by-cycle current limiting, improved line/load transient response, and simplified loop compensation vs. voltage-mode. |
| 52 kHz fixed-frequency oscillator | Enables predictable EMI filtering, eliminates external timing components, and supports standard off-the-shelf inductor selection guides. |
| Soft-start function | Reduces input in-rush current during startup by gradually increasing duty cycle - prevents input rail sag and protects upstream converters. |
| Internal 12 V reference | Ensures accurate output regulation without external feedback resistors - improves long-term stability and reduces component tolerance sensitivity. |
Applications
| Industrial Power Supply | Automotive Aftermarket Electronics |
|---|---|
|
Use Scenario: Generating stable 12 V from variable 9–16 V vehicle battery for infotainment modules or CAN gateways. IC Role / Device Role / Timing Role: Primary DC-DC boost regulator providing isolated, regulated 12 V rail with input brownout protection. Use Value: Operates across cold-crank (6.5 V) to load-dump (40 V) conditions while maintaining 12 V output within ±4%, supporting ASIL-B functional safety requirements. |
Use Scenario: Powering 12 V accessories (e.g., dashcams, GPS trackers) from single-cell Li-ion (3.0–4.2 V) or USB-PD sources. IC Role / Device Role / Timing Role: Step-up converter converting low-voltage portable source to standardized 12 V interface voltage. Use Value: Delivers up to 800 mA at >80% efficiency from 5 V input, enabling compact, thermally manageable designs without active cooling. |
| Point-of-Sale Terminal | Legacy Industrial Sensor Interface |
|
Use Scenario: Providing clean 12 V bias for thermal printers, magnetic stripe readers, and LED indicators in retail kiosks. IC Role / Device Role / Timing Role: Local DC-DC regulator converting 5 V system rail to higher-voltage peripheral rail. Use Value: Integrated UVLO and thermal shutdown ensure reliable operation during intermittent high-current printer pulses without system reset. |
Use Scenario: Powering legacy 12 V analog sensors (e.g., 4–20 mA transmitters, RTD bridges) from modern 3.3 V or 5 V microcontroller platforms. IC Role / Device Role / Timing Role: Isolated boost stage supplying sensor excitation voltage independent of main logic supply. Use Value: Fixed 12 V output eliminates calibration drift from resistor-divider tolerances; current-mode control rejects noise from shared ground paths. |
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 | No LB03 flow suffix; same electrical specs, identical TO-220 package and pinout. | Same functional behavior; LB03 denotes specific wafer fabrication flow and test screening per TI internal process control. | Select LM2577T-12/LB03 when traceability to TI's LB03 production flow is required for qualification or reliability reporting. |
| LM2577S-12 | TO-263 (S) surface-mount package; θJA = 37°C/W with 1 in² copper - lower thermal resistance than TO-220. | Better suited for automated SMT assembly and space-constrained layouts; requires different PCB footprint and thermal pad design. | Choose LM2577S-12 for volume production where thermal performance and board-space savings outweigh through-hole assembly needs. |
Compared with LM2577T-12/LB03, the base LM2577T-12 offers identical functionality but lacks LB03 traceability, while LM2577S-12 provides superior thermal performance in surface-mount form - both require layout and thermal redesign but retain pin-compatible boost regulator operation.
Availability
LM2577T-12/LB03 is available at Aetrix Electronics and suitable for industrial power supplies, automotive aftermarket electronics, and point-of-sale terminals requiring stable component supply with long-lifecycle support.
Supply support for LM2577T-12/LB03 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 high-reliability industrial components.
The LM2577 product line was designed for cost-effective, easy-to-implement DC-DC boost, flyback, and forward converter applications in industrial, automotive, and consumer systems where simplicity and robustness are critical.
FAQ
What is the maximum continuous output current supported by the LM2577T-12/LB03?
The LM2577T-12/LB03 supports up to 800 mA continuous output current under typical conditions (VIN = 5 V, TA = 25°C, with adequate PCB copper). This is constrained by its 3.0 A switch current limit, thermal resistance (θJA = 65°C/W), and efficiency (~80%). At higher ambient temperatures or lower input voltages, output current must be derated to maintain junction temperature below 125°C.
Does the LM2577T-12/LB03 require external feedback resistors?
No. The LM2577T-12/LB03 integrates an internal 12 V reference and connects the feedback pin internally to that reference, eliminating the need for external resistors. This distinguishes it from the LM2577T-ADJ variant and ensures fixed 12 V output with no calibration drift or layout sensitivity - a key advantage for production stability.
Can the LM2577T-12/LB03 operate from a 3.5 V input?
Yes. The LM2577T-12/LB03 has a guaranteed minimum operating input voltage of 3.5 V per its Absolute Maximum Ratings and Operating Ratings tables. At this voltage, it can still regulate 12 V output, though duty cycle approaches 95% and efficiency decreases; external inductor and diode selection must accommodate higher peak currents.
What is the purpose of the LB03 suffix in LM2577T-12/LB03?
The LB03 suffix identifies a specific TI wafer fabrication and test flow, indicating compliance with enhanced screening, lot traceability, and quality assurance protocols beyond standard commercial-grade LM2577T-12. It does not alter electrical specifications but provides documented process consistency for mission-critical or high-reliability deployments.
How does the soft-start function in the LM2577T-12/LB03 improve system reliability?
The soft-start function in the LM2577T-12/LB03 limits in-rush current during startup by gradually increasing the PWM duty cycle over ~1–2 ms. This prevents large input capacitor charging spikes, avoids triggering upstream current-limit protection, and reduces mechanical stress on electrolytic output capacitors - extending their service life in cyclic-power applications.
LM2577T-12/LB03 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/LB03 FAQ
1.How can I place an order for LM2577T-12/LB03 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2577T-12/LB03 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/LB03 reliable?
The price and inventory of LM2577T-12/LB03 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/LB03 is usually 5 days.
3.What payment methods are accepted for LM2577T-12/LB03?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2577T-12/LB03 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2577T-12/LB03?
LM2577T-12/LB03 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2577T-12/LB03 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/LB03?
For technical support, including LM2577T-12/LB03 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2577T-12/LB03 requirements.
6.How does Aetrix verify that LM2577T-12/LB03 is sourced from the original manufacturer or authorized distributors?
All LM2577T-12/LB03 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/LB03 meets industry standards.
7.What is the process for return or replacement of LM2577T-12/LB03?
All LM2577T-12/LB03 units undergo pre-shipment inspection (PSI). If there is an issue with LM2577T-12/LB03, 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/LB03 part is unused and in its original packaging.
Return procedure for LM2577T-12/LB03:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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