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Texas Instruments LM2577SX-ADJ
- Part No.:
- LM2577SX-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2577SX-ADJ.pdf
- Description:
- IC REG BST FLYBACK ADJ 3A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:4,510
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Product details
Overview
LM2577SX-ADJ from Texas Instruments is a monolithic step-up (boost) switching voltage regulator IC featuring an integrated 3.0A NPN power switch, 52 kHz fixed-frequency oscillator, current-mode control, soft-start, and protection circuitry including current limit, thermal shutdown, and undervoltage lockout. It operates from 3.5V to 40V input and delivers adjustable output voltage (≥1.23V) in boost, flyback, or forward topologies-commonly used in battery-powered instrumentation and industrial sensor power supplies.
For engineers reviewing the LM2577SX-ADJ datasheet, LM2577SX-ADJ pinout, LM2577SX-ADJ application, or LM2577SX-ADJ equivalent, key selection criteria include its 3.0A switch rating, 1.230V internal reference voltage, TO-263-5 (S) package thermal performance (θJA = 37°C/W with 1 in² copper), and compatibility with standard off-the-shelf inductors per TI's recommended list.
Technical Context
The LM2577SX-ADJ implements current-mode control architecture, where the error amplifier compares feedback voltage against a precise 1.230V reference and modulates peak inductor current via a comparator that terminates switch-on time. Its 52 kHz oscillator sets fixed switching frequency independent of external components, simplifying EMI filtering and layout.
Protection functions are hardware-based: undervoltage lockout activates below 2.70V (min), thermal shutdown engages at 150°C junction temperature, and current limiting restricts switch conduction to ≤3.0A under normal operation-though external inductor and diode selection must ensure peak switch current stays within 6.0A absolute maximum rating.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output topology | Step-up (boost), flyback, or forward converter - enables single-chip DC-DC conversion without external controller. |
| Input voltage range | 3.5V to 40V - supports wide-range inputs including 5V, 12V, 24V rails and multi-cell battery stacks. |
| Switch current rating | 3.0A continuous - defines maximum sustainable inductor peak current in boost configuration. |
| Reference voltage | 1.230V ±16mV - sets output voltage accuracy when using external resistor divider (VOUT = 1.23 × (1 + R1/R2)). |
| Oscillator frequency | 52 kHz ±10% - determines minimum inductor size and EMI profile; no external timing components required. |
| Thermal resistance θJA | 37°C/W (TO-263 with 1 in² PCB copper) - enables ~2.7W max power dissipation before reaching 125°C junction limit. |
| UVLO threshold | 2.70V to 3.15V - prevents erratic startup during brown-out; hysteresis ensures clean turn-on above 3.15V. |
Pinout & Package
LM2577SX-ADJ is housed in a 5-lead TO-263 (S) surface-mount package (NS Package Number TS5B), with the exposed tab thermally and electrically connected to Pin 2 (Ground). The package requires ≥1 in² of PCB copper for optimal thermal performance (θJA = 37°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - Input | Power input supply | Accepts 3.5V–40V unregulated DC; requires local ceramic bypass capacitor (≥100nF) near pin. |
| 2 - Ground | Power and signal reference | Common return for input, output, feedback, and compensation; connects to exposed thermal tab. |
| 3 - Feedback | Output voltage sensing | Monitors divided output voltage; regulates VOUT to 1.230V at this pin via external resistor divider. |
| 4 - Output | Switch collector node | Drives external inductor/diode; switches between VIN and open-circuit; withstands up to 65V. |
| 5 - Compensation | Error amplifier output | Provides loop compensation node; typically connected to RC network for stability in boost configuration. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 3.0A NPN switch | Eliminates need for external MOSFET or BJT, reducing BOM count and layout complexity in medium-power boost designs. |
| Current-mode control | Improves transient response and line/load regulation by directly sensing and limiting inductor current on-cycle. |
| Soft-start function | Reduces inrush current during startup by gradually increasing duty cycle, preventing input rail sag and output overshoot. |
| Fixed 52 kHz oscillator | Enables predictable EMI filtering and eliminates timing component tolerance drift, supporting consistent inductor sizing. |
| Thermal shutdown & UVLO | Hardware-level protection prevents damage during overload, short-circuit, or low-input conditions without software intervention. |
Applications
| Portable Medical Sensors | Industrial PLC I/O Modules |
|---|---|
|
Use Scenario: Powering 5V or 12V analog front-end circuits from a single 3.7V Li-ion cell in handheld diagnostic devices. IC Role / Device Role / Timing Role: Step-up regulator providing stable, low-noise bias for precision ADCs and op-amps. Use Value: Enables extended battery life via high-efficiency conversion (≥80% at 800mA) and eliminates need for dual-cell packs. |
Use Scenario: Generating isolated 12V auxiliary supply from 24V DC bus in programmable logic controller backplanes. IC Role / Device Role / Timing Role: Primary-side controller in flyback topology driving opto-isolated feedback loop. Use Value: Simplifies isolation design with integrated switch and current-sense capability, reducing transformer complexity. |
| Automotive Body Control Units | Smart Meter Power Supplies |
|
Use Scenario: Boosting 9V–16V vehicle battery voltage to regulated 12V for CAN transceiver and microcontroller peripherals. IC Role / Device Role / Timing Role: Input-stage regulator handling cold-crank (6.5V) and load-dump (40V) transients. Use Value: Wide 3.5V–40V input range and built-in UVLO/thermal protection ensure robust operation across automotive voltage extremes. |
Use Scenario: Providing 3.3V or 5V rail from utility-meter 3-phase AC-derived 12V DC bus with high reliability. IC Role / Device Role / Timing Role: Primary DC-DC stage in non-isolated buck-boost or flyback converter feeding meter SoC. Use Value: Long-term stability supported by 1.230V reference (±1.3% over temp) and minimal external component count. |
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-ADJ | Same die, but in 5-lead TO-220 (T) package with θJA = 65°C/W - higher thermal resistance limits continuous output current. | Suitable for lower-power, through-hole prototyping or heatsink-mounted designs where airflow is available. | Select LM2577T-ADJ only if board space allows TO-220 mounting and thermal budget permits reduced power handling. |
| MC34063AP | Lower 1.5A switch rating, 100 kHz variable-frequency operation, and ±2% reference tolerance vs. LM2577SX-ADJ's 1.230V ±1.3%. | Better suited for cost-sensitive, low-current (<500mA) applications where smaller inductors are preferred. | Choose MC34063AP when budget constraints outweigh efficiency and thermal performance requirements. |
Compared with LM2577T-ADJ, the LM2577SX-ADJ delivers superior thermal performance in surface-mount layouts; compared with MC34063AP, it offers higher current capability, tighter reference accuracy, and fixed-frequency operation for predictable EMI control.
Availability
LM2577SX-ADJ is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, automotive body control units, and smart meter power supplies requiring stable component supply and long-lifecycle support.
Supply support for LM2577SX-ADJ 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.
The LM2577 family was designed for cost-effective, medium-power DC-DC conversion in industrial, automotive, and instrumentation systems where simplicity, reliability, and wide input range are critical.
FAQ
What is the maximum output voltage achievable with LM2577SX-ADJ?
The LM2577SX-ADJ supports output voltages up to 60V, constrained by its 65V switch voltage rating and the equation VOUT ≤ 10 × VIN(min). For example, with a 3.5V minimum input, the practical upper limit is 35V. External component selection-including diode reverse voltage rating and output capacitor voltage rating-must align with the target VOUT to ensure safe operation.
Does LM2577SX-ADJ require an external compensation network?
Yes, the LM2577SX-ADJ requires an external RC network on the Compensation pin (Pin 5) to stabilize the control loop in boost configuration. Typical values are 1.2kΩ in series with 100nF, though exact values depend on inductor value, output capacitance, and desired phase margin. TI Application Note SNVA005 provides detailed design guidance for this network.
Can LM2577SX-ADJ be used in flyback topology with primary-side regulation?
Yes, LM2577SX-ADJ is explicitly qualified for flyback regulator use per its datasheet. In primary-side regulation, the feedback signal is derived from an auxiliary winding, and the IC regulates based on reflected output voltage. This eliminates optocouplers and secondary-side references, simplifying isolated supply design while maintaining ±5% output accuracy.
What is the purpose of the Soft Start pin on LM2577SX-ADJ?
The LM2577SX-ADJ does not have a dedicated Soft Start pin; soft-start functionality is internal and automatic, initiated at power-up. It gradually increases the duty cycle over ~1–2 ms to limit inrush current into the output capacitor, preventing input voltage droop and minimizing stress on the input source and external diode.
How does the current limit function in LM2577SX-ADJ during overload?
The LM2577SX-ADJ employs cycle-by-cycle current limiting: when sensed switch current exceeds the internal 3.0A threshold, the comparator terminates that switch-on period immediately. Under sustained overload, this results in frequency foldback and reduced average output current-not shutdown-allowing continued operation at diminished power until fault clears.
LM2577SX-ADJ 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:
- Not For New Designs
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Boost, Flyback, Forward Converter
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3.5V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.23V
- Voltage - Output (Max):
- 60V (Switch)
- 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-ADJ FAQ
1.How can I place an order for LM2577SX-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2577SX-ADJ 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-ADJ reliable?
The price and inventory of LM2577SX-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2577SX-ADJ is usually 5 days.
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LM2577SX-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2577SX-ADJ 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-ADJ?
For technical support, including LM2577SX-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2577SX-ADJ requirements.
6.How does Aetrix verify that LM2577SX-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2577SX-ADJ 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-ADJ meets industry standards.
7.What is the process for return or replacement of LM2577SX-ADJ?
All LM2577SX-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2577SX-ADJ, 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-ADJ part is unused and in its original packaging.
Return procedure for LM2577SX-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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