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Texas Instruments LM2577SX-12
- Part No.:
- LM2577SX-12
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2577SX-12.pdf
- Description:
- IC REG BST FLYBACK 12V 3A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:1,076
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Product details
Overview
LM2577SX-12 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 with ±4% output regulation, and includes undervoltage lockout, thermal shutdown, and current limiting-used in industrial power supplies and battery-backed instrumentation.
For engineers reviewing the LM2577SX-12 datasheet, LM2577SX-12 pinout, LM2577SX-12 application, or LM2577SX-12 equivalent, key selection criteria include input voltage range compatibility, output current capability at minimum VIN, thermal performance in TO-263 package, and external component count for boost topology implementation.
Technical Context
The LM2577SX-12 implements current-mode PWM control with an internal 52 kHz oscillator, enabling stable operation without external timing components. Its error amplifier compares feedback voltage against a 12 V reference (for fixed-output versions), modulating switch duty cycle to maintain regulated output under line and load transients.
It integrates a 3.0 A NPN power switch rated for 65 V off-state voltage, with built-in protection including undervoltage lockout (2.7–3.15 V threshold), thermal shutdown, and current limiting. The device requires only five external components-inductor, diode, input/output capacitors, and feedback network-for basic boost configuration.
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 linear regulators in space-constrained 12 V rail generation. |
| Input Voltage Range | 3.5 V to 40 V; supports wide-range DC inputs including automotive battery (9–16 V), industrial 24 V systems, and multi-cell Li-ion packs. |
| Switch Current Rating | 3.0 A continuous (6.0 A peak); defines maximum inductor peak current and limits achievable output power in boost topology. |
| Oscillator Frequency | 52 kHz nominal (42–62 kHz over temp); sets switching period for inductor sizing and EMI profile-low enough to minimize core loss, high enough for compact magnetics. |
| Junction Temp Range | −40°C to +125°C; specifies operational envelope for industrial and automotive ambient conditions when mounted on ≥1 in² copper area. |
| Efficiency | ≥80% at 5 V input, 800 mA load; determines thermal dissipation and battery runtime in portable applications. |
| Undervoltage Lockout | 2.70–3.15 V threshold; prevents erratic startup or brownout operation below minimum functional supply voltage. |
Pinout & Package
LM2577SX-12 uses a 5-lead TO-263 (S) surface-mount package (NS package code TS5B), with exposed thermal pad for enhanced heat dissipation. Thermal resistance θJA = 37°C/W with 1 in² PCB copper area.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 – Input | Power input supply connection | Accepts 3.5–40 V DC; must be decoupled with low-ESR capacitor near pin to suppress switching noise. |
| 2 – Ground | Power and signal reference node | Low-impedance return path for switch current and feedback circuitry; connects directly to thermal pad and PCB ground plane. |
| 3 – Switch | Collector of internal NPN transistor | Drives external flyback diode and inductor; carries pulsed 3.0 A current-requires short, wide trace routing. |
| 4 – Feedback | Regulation sense input | Internally referenced to 12 V; tied directly to output for fixed-version operation-no external resistor divider needed. |
| 5 – Output | Regulated 12 V output | Delivers up to 800 mA; requires bulk electrolytic capacitor (e.g., 680 µF/20 V) for ripple suppression and transient response. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 3.0 A NPN switch | Eliminates need for external power transistor, reducing BOM count and layout complexity in boost converters. |
| Current-mode control | Provides inherent cycle-by-cycle current limiting and improves line/load transient response without external compensation. |
| 52 kHz fixed-frequency oscillator | Enables predictable EMI filtering and consistent inductor sizing-no external timing components required. |
| Soft-start function | Reduces inrush current during startup by gradually increasing duty cycle, preventing input supply sag and output overshoot. |
| Thermal shutdown & UVLO | Protects device under overload, high ambient temperature, or low-input conditions-ensures robust field operation. |
Applications
| Industrial Sensor Power Supply | Automotive Auxiliary 12 V Rail |
|---|---|
Use Scenario: Powering analog sensor modules (e.g., pressure, temperature transmitters) from 5 V or 24 V industrial buses. IC Role / Device Role / Timing Role: Step-up regulator generating stable 12 V bias for op-amps, ADC references, and analog front-ends. Use Value: Delivers 800 mA at >80% efficiency with minimal external parts-reduces board area and thermal management burden. |
Use Scenario: Generating isolated 12 V supply for infotainment peripherals or CAN transceivers from vehicle battery (9–16 V). IC Role / Device Role / Timing Role: Boost converter maintaining regulated 12 V output despite cold-crank dips to 6 V. Use Value: UVLO (2.7–3.15 V) prevents malfunction during cranking; 65 V switch rating handles load-dump transients. |
| Portable Medical Instrumentation | Legacy Equipment Voltage Translation |
Use Scenario: Battery-powered handheld diagnostic devices requiring 12 V for LCD backlights or piezo drivers. IC Role / Device Role / Timing Role: High-efficiency boost stage converting single-cell Li-ion (3.0–4.2 V) to 12 V output. Use Value: 52 kHz switching enables use of small, low-cost inductors while maintaining >80% efficiency across battery discharge curve. |
Use Scenario: Retrofitting older 5 V logic systems needing 12 V for legacy relays, solenoids, or analog interfaces. IC Role / Device Role / Timing Role: Compact, drop-in boost solution replacing obsolete discrete designs or inefficient charge pumps. Use Value: TO-263 package allows surface-mount assembly; fixed 12 V output eliminates calibration overhead vs. adjustable alternatives. |
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 silicon, TO-220 through-hole package (θJA = 65°C/W); no thermal pad; higher thermal resistance. | Suitable for prototyping or low-power applications where heatsinking is feasible; not recommended for >500 mA continuous in compact enclosures. | Select LM2577SX-12 for surface-mount production, higher power density, and improved thermal performance with PCB copper area. |
| LM2587-12 | Pin-compatible upgrade with 5 A switch, wider input range (4–40 V), and improved efficiency (up to 85%); same TO-263-5 package. | Supports higher output current (1.5 A typical) and better light-load efficiency; requires updated inductor and diode ratings. | Choose LM2587-12 when upgrading for increased load capacity or tighter thermal constraints-no PCB layout change needed. |
Compared with LM2577T-12, LM2577SX-12 offers superior thermal performance via TO-263 thermal pad; compared with LM2587-12, it provides cost-optimized 800 mA capability with proven design maturity and lower BOM cost for established applications.
Availability
LM2577SX-12 is available at Aetrix Electronics and suitable for industrial sensor power supplies, automotive auxiliary rails, portable medical instrumentation, and legacy equipment voltage translation requiring stable component supply and long-term manufacturability.
Supply support for LM2577SX-12 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 broad distribution infrastructure.
The LM2577 family was designed 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 LM2577SX-12?
The LM2577SX-12 delivers up to 800 mA continuous output current under typical conditions (VIN = 5 V, TJ ≤ 125°C, with adequate PCB copper area). Peak switch current is internally limited to 3.0 A, but actual output current depends on input voltage, inductor value, and thermal management-derating is required above 60°C ambient.
Does the LM2577SX-12 require external feedback resistors?
No. The LM2577SX-12 is a fixed 12 V output variant-the feedback pin is internally connected to a 12 V reference, so no external resistor divider is needed. For adjustable versions like LM2577SX-ADJ, external resistors are required to set the output voltage.
What package type does the LM2577SX-12 use, and how does it affect thermal performance?
The LM2577SX-12 uses a 5-lead TO-263 (S) surface-mount package with an exposed thermal pad. With 1 in² of PCB copper area, its junction-to-ambient thermal resistance is 37°C/W-significantly lower than the TO-220 version (65°C/W)-enabling higher continuous power delivery in compact layouts.
Can the LM2577SX-12 operate from a 3.3 V input source?
No. The LM2577SX-12 has a minimum input voltage of 3.5 V and an undervoltage lockout threshold of 2.7–3.15 V. Operation below 3.5 V is not guaranteed; attempting to start from 3.3 V will result in failure to enable the internal switch and no output regulation.
What protection features are integrated into the LM2577SX-12?
The LM2577SX-12 integrates current limiting, thermal shutdown, and undervoltage lockout. These functions protect the device during overload, high ambient temperature, or low-input conditions-no external circuitry is required to implement basic fault protection in standard boost configurations.
LM2577SX-12 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- 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:
- Surface Mount
- Supplier Device Package:
- TO-263 (DDPAK-5)
LM2577SX-12 FAQ
1.How can I place an order for LM2577SX-12 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2577SX-12 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 LM2577SX-12 reliable?
The price and inventory of LM2577SX-12 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2577SX-12 is usually 5 days.
3.What payment methods are accepted for LM2577SX-12?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2577SX-12 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2577SX-12?
LM2577SX-12 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2577SX-12 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 LM2577SX-12?
For technical support, including LM2577SX-12 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2577SX-12 requirements.
6.How does Aetrix verify that LM2577SX-12 is sourced from the original manufacturer or authorized distributors?
All LM2577SX-12 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 LM2577SX-12 meets industry standards.
7.What is the process for return or replacement of LM2577SX-12?
All LM2577SX-12 units undergo pre-shipment inspection (PSI). If there is an issue with LM2577SX-12, 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 LM2577SX-12 part is unused and in its original packaging.
Return procedure for LM2577SX-12:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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