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Texas Instruments LM2577SX-12/NOPB
- Part No.:
- LM2577SX-12/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2577SX-12/NOPB.pdf
- Description:
- IC REG BST FLYBACK 12V 3A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:4,127
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Product details
Overview
LM2577SX-12/NOPB 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 internal 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 requiring compact, low-component-count DC-DC conversion.
For engineers reviewing the LM2577SX-12/NOPB datasheet, LM2577SX-12/NOPB pinout, LM2577SX-12/NOPB application, or LM2577SX-12/NOPB equivalent, key selection criteria include its TO-263-5 (S) package thermal performance (θJA = 37°C/W with 1 in² copper), 12 V ±4% output tolerance over temperature, soft-start function for in-rush current control, and compatibility with standard off-the-shelf boost inductors like AIE L415-0930.
Technical Context
The LM2577SX-12/NOPB implements current-mode PWM control using an internal error amplifier (transconductance = 370 μmho, gain = 80 V/V), reference voltage (12.0 V at feedback pin), and comparator that terminates switch-on time based on sensed inductor current. Its 52 kHz fixed-frequency oscillator eliminates external timing components and ensures predictable EMI behavior.
As a non-synchronous boost controller with integrated NPN switch, it requires only an external Schottky diode, inductor, and input/output capacitors. The device's soft-start circuit limits peak in-rush current by linearly ramping the error amplifier's compensation node voltage via a 5.0 μA internal current source.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 12.0 V (±4% min/max over temp and load); enables direct replacement of linear regulators without feedback divider. |
| Input Voltage Range | 3.5 V to 40 V; supports wide-range industrial inputs including 5 V, 12 V, and 24 V rails with headroom for transients. |
| Switch Current Rating | 3.0 A continuous (6.0 A absolute max); defines maximum inductor peak current and limits usable output power at low VIN. |
| Oscillator Frequency | 52 kHz (±8% over temp); sets minimum inductor size and enables use of low-cost, high-saturation-current ferrite cores. |
| Efficiency | ≥80% at VIN = 5 V, ILOAD = 800 mA; determines thermal load and heatsink requirements in enclosed environments. |
| Thermal Resistance | θJA = 37°C/W (with 1 in² PCB copper); directly impacts maximum ambient operating temperature at full load. |
| Soft-Start Time | Controlled by 5.0 μA internal current into COMP pin; sets typical startup time to ~20 ms with 100 nF compensation capacitor. |
Pinout & Package
LM2577SX-12/NOPB uses the TO-263-5 (S) surface-mount package (NS package code TS5B), with exposed thermal pad for enhanced heat dissipation. Pin 1 is marked by notch or dot; leads are bent and staggered for automated assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VIN) | Input supply connection | Accepts 3.5–40 V DC; must be decoupled with ≥100 μF low-ESR capacitor near pin to suppress switching noise. |
| 2 (GND) | Power ground reference | Common return for input cap, output cap, and diode cathode; tied to thermal pad for optimal thermal conduction. |
| 3 (SW) | Switch collector node | Drives external Schottky diode anode; voltage swings from VIN to >VOUT + VF during operation. |
| 4 (FEEDBACK) | Output voltage sense input | Internally connected to 12 V reference; shorted to VOUT for fixed-output configuration (no resistor divider needed). |
| 5 (COMP) | Error amplifier output | Connects to RC network for loop compensation; sets bandwidth and phase margin of regulation loop. |
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 space-constrained designs. |
| Current-mode control | Provides inherent cycle-by-cycle current limiting, improves line/load transient response, and simplifies loop compensation. |
| 52 kHz fixed-frequency oscillator | Enables predictable EMI filtering design and avoids audible noise; allows use of standardized inductor families (e.g., AIE 415-0930). |
| Soft-start function | Reduces in-rush current during startup by controlling COMP pin voltage ramp, preventing input rail collapse and diode stress. |
| Comprehensive protection | Includes undervoltage lockout (2.7–3.1 V threshold), thermal shutdown (>150°C), and current limiting-ensures robust operation under fault conditions. |
Applications
| Industrial Power Supply | Automotive Accessory Module |
|---|---|
|
Use Scenario: Generating stable 12 V from a 5 V or 9 V intermediate rail in programmable logic controllers (PLCs) with limited board area. IC Role / Device Role / Timing Role: Primary DC-DC boost converter providing regulated 12 V for analog sensors, RS-485 transceivers, and microcontroller peripherals. Use Value: Enables single-rail system architecture with 80% efficiency at 500 mA, reducing thermal load versus linear solutions and eliminating need for external MOSFET drivers. |
Use Scenario: Powering USB charging ports and infotainment displays from vehicle battery (9–16 V) with cold-crank immunity down to 6 V. IC Role / Device Role / Timing Role: Input-stage boost regulator maintaining 12 V output during engine cranking events where battery dips to 6 V. Use Value: 3.5 V UVLO threshold and 40 V max input withstand capability allow reliable operation across automotive battery transients per ISO 7637-2. |
| Medical Portable Device | IoT Edge Node |
|
Use Scenario: Providing isolated 12 V bias for op-amps and ADC references in handheld diagnostic tools powered by Li-ion (3.0–4.2 V). IC Role / Device Role / Timing Role: High-efficiency boost stage preceding isolated DC-DC module, minimizing battery drain during extended measurements. Use Value: 800 mA output capability supports multi-channel signal conditioning while TO-263 thermal performance enables fanless enclosure design. |
Use Scenario: Converting energy-harvested 3.3 V (from solar or piezoelectric sources) to 12 V for actuator drivers or cellular modem transmission bursts. IC Role / Device Role / Timing Role: Primary voltage step-up stage enabling high-voltage peripheral operation from ultra-low-power sources. Use Value: Low 7.5 mA quiescent current (switch off) and soft-start prevent brownout during intermittent energy availability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2577T-12 | TO-220-5 through-hole package; higher θJA = 65°C/W; same electrical specs and pinout. | Suitable for prototyping or low-volume assemblies where manual soldering or heatsink mounting is preferred. | Select LM2577T-12 when thermal management via mechanical heatsink is feasible and SMT assembly is unavailable. |
| LM2577M-12 | 24-pin surface-mount SOIC package; lower current rating (ISWITCH ≤2.0 A); different pinout and footprint. | Used in space-constrained but thermally benign environments where lower output current suffices. | Choose LM2577M-12 only if output load ≤500 mA and PCB real estate permits larger SOIC footprint with reduced thermal mass. |
Compared with LM2577T-12 and LM2577M-12, the LM2577SX-12/NOPB offers superior thermal performance in SMT form factor (37°C/W vs. 65°C/W or uncharacterized SOIC), supports full 800 mA load without derating, and maintains identical functional behavior-making it optimal for production-grade industrial and automotive boost converters.
Availability
LM2577SX-12/NOPB is available at Aetrix Electronics and suitable for industrial power supplies, automotive accessory modules, and portable medical devices requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LM2577SX-12/NOPB 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 as a cost-effective, easy-to-use SIMPLE SWITCHER® solution for non-isolated DC-DC boost, flyback, and forward converter topologies-targeting applications where minimal external components and proven thermal robustness are critical.
FAQ
What is the maximum output current achievable with LM2577SX-12/NOPB?
The LM2577SX-12/NOPB supports up to 800 mA output current under typical conditions (VIN = 5 V, TA = 25°C, with adequate PCB copper). This limit is constrained by the 3.0 A switch current rating, thermal resistance (θJA = 37°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. Full-load operation requires proper thermal pad soldering and ≥1 in² copper pour.
Does LM2577SX-12/NOPB require an external feedback resistor network?
No. The LM2577SX-12/NOPB has an internally trimmed 12 V reference connected directly to the FEEDBACK pin. For fixed 12 V operation, the FEEDBACK pin is shorted to the output (VOUT), eliminating external resistors. This differs from the adjustable LM2577-ADJ version, which requires a two-resistor divider to set output voltage. Using the LM2577SX-12/NOPB in adjustable mode is not supported.
What diode type and specifications are recommended for use with LM2577SX-12/NOPB?
A Schottky diode rated for ≥30 V reverse voltage and ≥3 A average current is recommended-such as the MBR2030CT or SB560. Schottky diodes minimize forward voltage drop (VF ≈ 0.5 V), improving efficiency and reducing thermal stress. Fast-recovery diodes (VF ≈ 0.8 V) may be used but reduce efficiency by ~2–3% and increase diode power dissipation. Peak inverse voltage must exceed VOUT + VIN(max) = 52 V.
How does the soft-start function operate in LM2577SX-12/NOPB?
The LM2577SX-12/NOPB integrates a 5.0 μA current source that charges the external capacitor on the COMP pin during startup. This linearly ramps the error amplifier output, gradually increasing duty cycle and limiting in-rush current into the output capacitor. With a typical 100 nF compensation capacitor, soft-start duration is ~20 ms. No external components are required-the function is enabled automatically at power-on when UVLO exits.
Can LM2577SX-12/NOPB be used in flyback or forward converter topologies?
Yes. The LM2577SX-12/NOPB is explicitly specified for flyback and forward converter applications per its datasheet. In flyback mode, the transformer primary replaces the inductor, and the secondary delivers isolated output. In forward mode, a reset winding or RCD clamp is required. Both configurations leverage the same 3.0 A NPN switch and current-mode control-but require topology-specific transformer design, snubbing, and output rectification per TI Application Hints.
LM2577SX-12/NOPB 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/NOPB FAQ
1.How can I place an order for LM2577SX-12/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2577SX-12/NOPB 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/NOPB reliable?
The price and inventory of LM2577SX-12/NOPB 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/NOPB is usually 5 days.
3.What payment methods are accepted for LM2577SX-12/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2577SX-12/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2577SX-12/NOPB?
LM2577SX-12/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2577SX-12/NOPB 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/NOPB?
For technical support, including LM2577SX-12/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2577SX-12/NOPB requirements.
6.How does Aetrix verify that LM2577SX-12/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2577SX-12/NOPB 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/NOPB meets industry standards.
7.What is the process for return or replacement of LM2577SX-12/NOPB?
All LM2577SX-12/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2577SX-12/NOPB, 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/NOPB part is unused and in its original packaging.
Return procedure for LM2577SX-12/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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